CHAPTER 7 - WWII JAPANESE MILITARY TACTICS - section 2
1. ORGANIZATION FOR DEFENSE.
a. General.
(1) Object.
The object of the defensive as visualized by the Japanese does not differ in principle from that of other armies. The Japanese seek to suplement inferiority in strength by the utilization of such material advantages as the terrain, fortifications, and thorough preparations for combat, and to break up hostile attacks by the combined use of fire power and counterattacks.
(2) Japanese attitude.
The very word "defense" is distasteful to the Japanese, and is contrary to the Bushido (warrior) spirit with which the Japanese soldier has been imbued since childhood. When forced on the defensive, therefore, he is at all times preparing and planning counter attacks to break up the enemy's assaults and so regain teh initiative. The Japanese first counter attack in force; if such attacks fail they commence fanatical, suicidal, small scale attacks. These are supplemented by many small infiltration operations. When all such efforts fail, they will defend, literally, to the last man.
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b. Selection of a position.
When it has been decided that a force will take up teh defensive, the commander makes his reconnaissance, taking into consideration the current battle situation, the nature of the terrain, and the strength and composition of his force. Whenever possible he will choose ground which provides natural antitank obstacles, good fields of fire, camouflage, and all those features which make defense and ultimate counter attack easy. With his area selected, the commander then directs the subordinate elements of his force to their respective positions. If tanks are present they will go forward, along with detachments of infantry to provide a screen while the position is being organized. c. Main battle position. This position comprises the infantry main line of resistance, firing position of the main line of artillery, and shelters for reserves. If the Japanese commander has sufficient troops at his disposal, he will organize a position in depth to |
Figure 2. Organization of a battalion position. |
Each sector commander is responsible for the construction of defenses and the general defense of his area in accordance with the main plan.
In taking up their positions, the Japanese lose no time in digging in and making their respective sectors in strongpoints. Reconnaissance of some of their positions has shown the usual priority of tasks to be as follows:
Figure 3. Typical Japanese cave positions. |
(1) Gun emplacements and pillboxes.
(2) Fox holes and trenches. (3) Tunnel and cave systems. (4) Antitank obstacles, wire, and mines. (5) Additional pillboxes. The defense is built around a series of pillboxes, usually mutually supporting, and, if time permits, linked by a natural or constructed system of caves and tunnels. If a pillbox is not supported by neighboring pillboxes, it will usually be covered by rifle and light automatic fire from fox hole positions on one or both of its flanks. These pillboxes, where possible, will be so sited as to take maximum advantage of observation, fields of fire, and inaccessibilty to the attacker. The last point may be adopted even to the exclusion of wide fields of fire, and utmost use will be made of high ground. |
The whole Japanese defense position will be built to give protection from tanks. If there are no natural obstacles to the front or flanks, tank ditches may be dug, or narrow streams may be widened and deepened to make them effective obstacles. Gaps between these obstacles are mined and covered by fire. The mines very frequently are boosted by placing artillery shells beneath them. Likely roads of approach to the position will probably be blocked and mined. These road blocks may take the form of formidable cement structures or merely felled trees.
Great stress is laid on camouflage and concealment. In addition to the normal precautions taken to blend guns, pillboxes, and fox holes into the natural background of the terrain, tunnels frequently will be dug between pillboxes and various unit headquarters. Natural caves will be utilized whenever they are in the vicinity. These will be improved by tunnels and additional ports, by enlarging shelter caverns, and by camouflage. All cave positions will be tied in with needed surface fortifications such as pillboxes and fox holes, and the entire system will constitute a most effective area for defense.
When the main Japanese position is built on a reverse slope, observation posts and patrols initially willbe placed on the summit and forward slopes. As the position is developed, pillboxes are constructed on the forward slopes as well.
Where there is no commanding ground, the Japanese center their defenses around native villages, digging in usually in the bordering hedges, under trees, or in thick bamboo clumps. Such positions have proved effectively obstacles to our tanks. The frontage for a battalion in defense naturally depends on teh type of terrain; it has varied from 800 to 5,000 yards. A Japanese document gives the normal battalion frontage as 1,500 to 2,000 yards with a depth of 1,000 yards.
d. Outpost positions.
The outpost position ( Keikai Jinchi ) is set up in front of each sector to observe the enemy's approach, slow his advance, and attempt to anticipate his plans of attack. Its disposition depends upon the terrain, but it is generally from 1,500 to 3,000 yards in from of the main line of resistance, so as to be within supporting range of light artillery. The Japanese rarely developed an intricate outpost defensive system, but invariably select commanding ground where they may observe most effectively the enemy's approach and make the best use of their limited fire power. The strength of the outpost position varies with the mission ordered by the main force commander, but the Japanese prescribe that it will be no stronger than absolutely necessary. They aldo emphasize that the outpost positions must not form a continuos line. Isolated cases have been noted where they have eliminated outpost positions entirely. This probably has been attributed to a paucity of troops, and has been done where the defense commander considered small reconnaissance patrols adequate.
e. Advanced defensive positions.
In addition to his outpost positions, the Japanese defense commander may order the occupation and organization of an advanced defensive position ( Zenshin Jinchi ) between the outpost and main positions . Its purposes are to prevent, for as long as possible, the occupation by hostile forces of critical points of terrain near the main defensive zone; to delay the enemy's preparations for an attack; and to induce him to launch his attack in a false direction. The setting up of such positions, which include machine guns and antitank weapons, is not coomon Japanese practice. Typical cases where they have been encountered are:
(1) where, in order to obtain observation, the outposts have been pushed well forward, leaving an important ridge in the foreground of the main position ungarrisoned;
(2) Where an oblique position is organized between the outpost and main positions, with one flank resting on the outpost line of resistance, while the other rests on the main line of resistance, thus inducing the enemy to expose a flank.
f. Reserves, artillery, command posts.
(1) Reserves.
The present Japanese trend indicates that they are holding a larger proportion of their defense forces in reserve than therefore, quite in accordance with their doctrine of aggressive defense. In some cases, they have been known to hold almost a half of their strength in readiness for the counter attack. Troops held for counter attack are disposed behind the main infantry line, usually in shelters and tunnels which are protection against the heaviest artillery and air bombardments. Their exact location will be dependent on the nature of the terrain and the battle situation. Tanks will usually be attached to the reserve force.
(2) Artillery.
Japanese guns will normally be dispersed behind the infantry main line. Usually sinlgy, sometimes in pairs. They are housed in well camouflaged emplacements or pillboxes disposed in depth. Some of the pieces may be sited well forward in the main position in order to support the outpost troops. Many alternate emplacements will be prepared in readiness for moving the guns when it is considered that they have been spotted.
(3) Command posts.
These generally are established in well sheltered positions in rear of the main line of resistance; that of the division is usually located at a distance of about 5,500 yards, that of the infantry group 2,700 yards, and that of the infantry regiment at about 1,300 yards in rear of the main line of resistance.
2. CONDUCT OF THE DEFENSE.
a. Defense of the outpost positions.
Troops of the various sector outpost positions are the first to observe and come in direct contact with the attacker. In their mission to delay the attack, defenders of outpost positions will be send out small fighting patrols to harass the enemy. Artillery support will be given by guns situated in the main position. The degree of resistance by troops in outpost positions depends upon the particular nature of their mission. Sometimes they are ordered to defend their positions to the last man in order to delay the attack as long as possible. More frequently, however, when it becomes apparent that they no longer can hold off the attackers, they will withdraw. This withdrawl is made along previously reconnoitered routes, and is often planned to lead the attackers into a trap where they will expose a flank.
b. Defense of the advanced position.
The actions of the advanced position will follow closely that of the outpost position. It will invariably withdraw, however, when it can no longer hold up the attack. Clear orders are issued by the main defense commander specifying the time and routes of withdrawl and giving new missions for the force when it reaches the main position.
c. Defense of the main battle position.
One of the most difficult tasks of a force attacking a Japanese position is to locate that position. The enemy's skill in remaining concealed and observing absolute silence has on many occassions given him the element od surprise necessary for countering an attack.
When, however, the Japanese realize that their position has been spotted, and an attack is inevitable, hey brng down artillery and mortar fire in the area where the hostile infantry is forming. The Japanese do not make the maximum use of these weapons by massing the fire, but put it down sporadically. They will frequently fire at the same time as do hostile guns, placing the shells on the enemy's forward advancing infantry. Their intention is to demoralize hostile troops by giving them the impression that their artillery rounds are short ranged.
Japanese commanders send out patrols - chiefly of the suicide type - to harass the attacker and to attempt to break up his plan of attack. These suicide patrols, although their mission usually precludes their return, are not just thrown away. They use every ddevice to cause the maximum number of casualties among hostile leaders, and to destroy as many installations as possible before they themselves are killed. One common mission of such patrols is the destruction of artillery pieces which are causing them trouble.
Japanese snipers are placed forward to provide a protective screen. The snipers usually do not make a stand, but attempt to disorganize the attack and then withdraw. They are always well camouflaged and take up concealed positions in bushes or up trees. On occassion, they do not open fire on the first wave of attack but remain concealed until targets are offered in the rear of the first or in the second wave.
As the hostile force advances to the main line, Japanese troops will first defend by small arms fire and later with the bayonet. as one strong point is occupied, fire and bayonet charges may be exposed from neighboring strongpoints on the flanks or rear of the attacker. Mortar fire will be brought to bear on teh position; any Japanese troops thre at the time will go to their tunnels or hide in pillboxes awaiting their chance to counter attack. Parties will come from the rear, attempting to infiltrate and reoccupy positions.
The Japanese will fight tenaciously as their positions are taken. They will not diw always in their strongpoints, if they consider that, by moving to positions in the rear, they have chance of regaining the initiative. Troops in cave areas, however, often have died in their positions because orders to do so have been given them, or because their means of escape have been blocked too soon.
d. Counterattack.
Japanese doctrine dictates that when an enemy penetrates the defense position, a swift daring counterattack must be launched, and their operations thus far have revealed that they practice this. It must be borne in mind, however, that these counter attacks are not merely disorganized assaults. Defense commanders invariably prepare several plans to meet likely breakthroughs by the hostile force. In one large scale defensive operation, seven separate counter attack plans had been devised.
These counter attacks normally follow the form of the accepted Japanese offensive plan. The main line infantry engages and attempts to hold the hostile push, while detachments from the reserve are sent around to one of both of the enemy's flanks in an encircling movement. at the same time, small infiltration parties are sent out. The encircling force is to cut the attacking force in two; while infiltrating parties make suicide attacks on tanks, vehicles, guns, and headquarters.
Tanks may be employed, usually singly, as mobile pillboxes; the Japanese rarely use then to counter our tanks. In addition, artillery and mortars will be employed to support the forward advance of the counterattacking troops.
3. COMMENTS.
Although the recent trend of event has forced the Japanese into all out defensive, they by no means have lost their aggressive attitude, and it is on the attitude that they base their normal defensive operation.
Japanese small unit defensive tactics are good. They are adept at digging themselves in and putting a position in a state of defense in an incredibly short time. It is questionable, therefore, whether the term "attack of a hastily prepared position" is ever applicable against the Japanese. It should be remembered by the attacking force that the longer attack is delayed, the more difficult it will be to dislodge the Japanese who are constantly improving their positions.
There is no doubt that the majority of positions contain far more defenses than the defending force can possibly man. This permits greater maneuver within the position and tends to give the attacker an impression of greater strength than actually exists.
The main fault of the Japanese defensive appears to be in the execution of large scale operations whicj lack thorough coordinated planning. Small units defend their strongpoints tenaciously, launching frequent daring counterattacks which inflict substantial casualties. Large scale counterattacks have been launched when the situation permitted, but the results obtained from them have not been commesurate with the men and materiel expended.
1. THE WITHDRAWL.
a. GENERAL.
No information has been obtained as to when a Japanese commander considers a withdrawl required or justified, but experience indicates that he will rarely whithdraw unless such a movement gives him a tactical advantage in his current operation. The general principles followed are similar to our own, except that the Japanese appear to have little objection to a daylight withdrawl.
b. Preparations.
The Japanese division commander, in anticipation of a withdrawl, first attempts to clear his rear area of supply troops and installations, improves the roads which he expects to use, and orders preparations for demolitions to delay the enemy pursuit. All preparations are made with the utmost secrecy while preserving a bold front.
c. Execution by day.
Breaking of contact by the front line infantry is done under the protection of local covering forces, disposed from 1,500 to 2,000 yards behind the firing line. These troops are obtained from battalion, regiment, or other reserves not committed to the front line fighting. The position occupied is, when possible, to the flank of the line of retreat on commanding ground that permits overhead fire in support of the retiring troops. The local covering forces give support by fire and, on occassions, may launch a counterattack. Size of the local covering force varies with the strength of the terrain on which it is to defend, but it appears to be only a small percentage of the total unit.
In addition to these local detachments, the division commander organizes a general covering force ( shuyo jinchitai ) behind which he reforms the major elements of his command. The division reserve is usually the main component of this covering force which, in principle, is made up of the freshest troops available. The bulk of the division artillery withdraws and deploys behind this covering position to protect the withdrawl. The Japanese try to place the covering position at an oblique angle to teh axis of retreat and from 3,000 to 5,000 yards in rear of the front line. The division command post is set up behind the covering position for the purpose of controlling the withdrawl and organizing the subsequent retirement for which the troops on the covering position eventually become the rear guard.
Protected by the covering forces, the front line infantry withdraws straight to the rear. The Japanese feel that it is desirable for all front line units to pull back simultaneously, but often some must hold on longer than others. The division artillery, the bulk of which has already retired to the general covering position, supports the withdrawl. In some sectors, a local counter attack amy be launched in an attempt to hide the withdrawl intention. Retreating units reform progressively, arriving by many small columns in the general assenbly area behind the general covering position. Here, division march columns are formed and directed toward the final terrain objective of the withdrawl. The engineers execute demolitions; mines are laid and special attention is paid to the setting of booby traps. Precautions are taken to prevent turning movements around the flanks by enemy pursuit detachments.
d, Execution by night.
The night withdrawl differs from that in daylight in the following important respects:
(1) The local covering mission is performed by a "shell" of small detachments left in position on the front line throughout most of the hours of darkness.
(2) Retiring units reassemble and form march columns nearer the front line than is the case in daylight.
(3) A general covering position is not normally organized. Detailed preparation in daylight is necessary prior to a night withdrawl.
The breaking of contact by the front line infantry is done under the cover of a thin line of infantry detachments, strong in machine guns and supported by a small amount of artillery. This "shell" simulates the usual sector activity throughout the night to deceive the enemy and, if attacked, sacrifices itself in its position to protect the retirement. Its time of withdrawl, usually about dawn, is set by the division commander. The mission of the "shell" may be facilitated by local attacks executed early in the night by front line detachments prior to their withdrawl. A small general covering force, strong in cavalry and mobile troops, may be organized to get the "shell" away without undue losses.
In action of the front line units is essentially the same as in daylight, except that the assembly areas are farther forward.
e. march plan.
Details of a typical Japanese infantry march plan, which required a mixed force to cover approximately 13 miles a night, were contained in a Japanese order for a withdrawl along the jungle coast of northeastern New Guinea. The forces was one of three from a single division which were involved in the movement. According to the plan, the force was to march from 2000 to 0400 hours on successive nights until it reached its destination, 50 miles away. The order warned that if any hostile activity occurred, it probably would consist of landings on the coast. Communications, security, bivouac, and care of the weak and wounded were some of the problems dealt with in the order.
The force consisted of the follwing units:
- Part of division headquarters.
- Infantry battalion less two rifle comnpanies.
- Battery of mountain artillery.
- Company of engineers.
- One wire and one radio signal section.
- Military polkice detachment.
- Medical detachment.
- Litter bearer platoon.
The force was divided into three groups to facilitate the march and to diminish vulnerability to air attack. Each group, organized to fight independently, was instructed to attack immediately in case of a hostile amphibious attack. However, the group commanders were instructed to combine their strength, if possible, in the event contact was made with the enemy.
Communications between the three groups were to be maintained by runners. Each group was ordered to detail a noncommissioned officer and two orderlies to the force headquarters to receive and relay messaegs. The group commanders were required to report their position, bivouac areas, and the next day's route data by 1,000 hours every day, and the force commander was to furnish similar information to the division commander.
Sich and weak soldiers were to be hospitalized or sent ahead of the march column. During the movement, medical examinations were to be made independently by each group.
Unless weather, terrain, or unexpected hostile action made it necessary to alter the plan, the force was to march for 8 hours and be at a bivouac area and ready to take cover by dawn. During the day, until 1800 hours, the troops were to keep under cover, rest, and make preparations for cooking. The 2 huors from 1800 to 2000 hours were assigned for cooking the evening meal and also enough food to last until the next cooking period the following evening.
The rate of march was set at 1 1/4 miels per 30 minutes, followed by 15 minutes rest. INtervals were fixed at 55 yards between units, and at six tenths of a mile between the three groups into which the march column was divided. In order to maintain a uniform pace, proper intervals, and the time schedule, officers were cautioned to keep firm control of their units, to use connecting ropes, and to maintain contact by use of panels and other visual signaling.
All personnel were cautioned to watch the sea closely during the march - sepcially at night - and to be prepared at all times to meet any unexpected hostile action from the direction. To ensure secrecy of movement, native villagers were to be avoided, and certain precautions were to be observed in making camps. Bivouac areas were to be situated in suitable cover and camouflaged, and were to be no closer to a village, road, or beach than 325 to 450 yards. Tents were to be pitched 30 to 55 yards apart. Fires were prohibited during the day, and the troops were forbidden to walk on roads and beaches and in villages during daylight.
f. Comment.
The chief criticism of the Japanese in the withdrawl is not in the manner in which they carry out an organized and well planned withdrawl, but in their failure to appreciate the value of such an operation. Instances have occurred where they have thrown away hundreds of troops in a futile attempt to hold positions to the last man, when, by carrying out an organized withdrawl, they could have moved to positions in their rear and reinforced other units. This failure is no doubt the result of the Japanese dislike of any retrograde movement and their over emphasis on attack.
Even in the planned withdrawl the note of aggressiveness is ever present. When a Japanese commander initiates a withdrawl he expects to return over that same ground in his ultimate counterattack. If he cannot take his guns with him during the withdrawl he tries to bury them ready for the counteroffensive.
Decentralization of command and the practice of leaving samll unit commanders without any specific orders have tended, in some cases, to make a Japanese withdrawl almost a rout. There is no doubt that these cases will continue until the Japanese realize the value of the withdrawl and become better trained in its execution.
2. DELAYING ACTION.
a. General.
The Japanese do not recognize the delaying action as a separate and distinct form of military operation, but include it in the broader term jikyusen (holding out combat). This expression is used to cover, in addition to pure delay, a number of types of operations characterized by a desire to avoid a fight to a finish, but in which the idea of delay is somewhat remote. Thus, in addition to the typical delay situations, such as the action of rear guards and covering forces, the Japanese treat under jikyusen demonstrations, reconnaissance in force, and night attacks designed to cover a withdrawl.
Figure 4. Examples of Japanese delaying positions. |
In the subsequent discussion an effort is made to disregard the elements not bearing directly on delay which the Japanese inject
into the treatment of jikyusen .
The usual purpose of delaying action is to gain time to contain or to divert a superior enemy while avoiding decisive combat. "although these ends are frequently achieved by defensive action, there are occassions when the mission can be accomplished only by offensive action". The preceding sentence is a literal translation from the Sakusen Yomurei . Elsewhere, the same regulation urges that even when defensive measures are initially better adapted to the situation, the commander always must be ready to take advantage of an opportunity for offensive action. However, when offensive action is indicated, in order to avoid becoming deeply engaged, the division commander designates limited objectives and rigidly controls the number of troops committed. In comparison with the meeting engagement, fronts of deployment are widein such an offensive action. Mobile troops, well equipped with automatic weapons and artillery, are best adapted to delaying actions. The infantry fire fight generally takes place at long ranges, and the engagement is broken off when the enemy draws near. Frontages are wide, and the breadth is obtained by increasing the intervals between occupied key positions. Reserves are kept large to cover withdrawls, to give continuity to the resistance of the delaying force, and to provide troops for such limited offensive actions as the commander may undertake. b. Choice of a delaying position. While the situation may force the commander to seek the required delay on a single position, such a disposition creates a danger of becoming involved in a fight to the finish or in a coslty withdrawl at close range from the enemy. It is therefore preferable to delay on successive |
c. Conduct of the delaying action.
When the decision has been reached to delay anadvanceing enemy, the Japanese division commander sends out his cavalry to establish and maintain contact and to initiate the delaying action within limits of its combat capacity. He then selects the position or positions upon which he expects to gain the required time for the accomplishment of his mission. He often will send forward an infantry detachment, of from two companies to a battalion, to occupy an advanced position ahead of the first delaying position. Such an advanced position is located within range of artillery support from the delaying position in accordance with the principles for choosing an outpost line of resistance. These forward troops assist the cavalry, as the latter falls back to the flanks of the delaying position, and impose some loss of time on the advancing enemy.
The enemy is taken under fire by the Japanese division artillery at extreme ranges. Artillery positions are close behind the infantry, grouped together for ease in fire direction in the belief that there is little to fear initially from hostile counterbattery. Eventually, the infantry machine guns join in the fire fight as the enemy comes within range.
The Japanese division commander makes every effort to hold out a large reserve. In cases noted, this amounted to from a third to a half of his infantry and a battalion of artillery. The main purpose of this large reserve is not to counterattack (although saome of it on accasion may engage in local offensive action) but to reconnoiter, rpepare, and occupy the next delaying position from which it covers the withdrawl if the troops of the first position.
The Japanses thus contemplate, in effect, delay on successive positions occupied simultaneously, although this form of action is implied rather than clearly defined.
The engineers of the division find their principal missions in road maintenance, route marking, and the preparation and execution of demolitions. The last are carefully planned to cover the flanks and routes of direct approach to the delaying positions. as in oher forms of cpmbat, the Japanese count heavily on measures of deception to assist in accomplishing the delaying mission. Devices used to create this deception are:
- Dummy engineer works.
- Demonstrations.
- Economy of force in wooded and covered areas while strength is displayed in open terrain.
- Roving artillery.
- Proclamations.
- Propaganda.
All these measures aim to create an impression of strength which will cause the enemy to adopt a cautious attitude toward the delaying force. In spite of the fact that such measures impose fatigue on the troops and, in extreme cases, may lead to a serious dispersion of effort, the Japanese feel their use is justofied.
Japanese troops on the delaying positions retire on order of the division commander while the enemy is still at a distance, unless the mission specifically requires a long delay on a single position. When the hostile infantry arrives within 1,000 yards of the position, withdrawal is begun, while troops on the next delaying position provide covering fire. Detachments left in the zone between the positions effect intermediate delay. WHen it has not been possible to prepare and man a second position, the division commander tries to put off his withdrawal until nightfall.
d. Comments.
As a defensive form of combat the delaying action does not appeal to the Japanese soldier who thinks first and last of fixing bayonets and moving forward. Influenced by the strength and weakness of this psychology, the Japanese commander often will choose offensive action when the defensive is better suited to the immediate situation. It has been noted that a little fresh encouragement has been given in the new Japanese field service regulations to the use of offensive action to obtain delay, an encouragement of which Japanese commanders can be expected to take full advantage in order to seek delay through attack. It is felt that this over aggressiveness may ill serve the usual purpose of delay.
The injuction to hold out a large reserve does not agree with the usual teachings on delay. A reserve suggests the intention to counterattack, whereas a delaying position usually is abandoned before the enemy has come within counterattacking range. In the practice of map problems, this large reserve was always used to occupy a rear delaying position, so that the operation became, in effect, a delay on successive positions simultaneously occupied. Thus, the requirement of holding out a large reserve, in spite of its apparent contradiction, becomes reconciled with orthodox tactics.
The Japanese dislike for using their light artillery at long ranges tends to keep successive delaying positions relatively close together (2,000 - 4,000 yards). It is generally considered that 5,500 yards is the extreme limit of effective ground observation, and it is rare to assign missions beyond that range. Japanese artillery has had little experience in fire with air observation.
Despite this failing, it is reasonable to suppose that the Japanese have learned the latest methods of withdrawal as employed by modern armies which place great emphasis on the use of tanks, mobile artillery, motorized infantry, mines, tank traps, aircraft, amd a new concept of distance.
1. EMPLOYMENT IN MASS.
Although few large commitments of Japanese tanks have occurred so far outside the Chinese theater, their army tank school gives precise instructions for the employment of large armored formations. For an attack on a lightly held enemy position Japanese doctrine maintains that a minimum of 30 to 40 tanks are required. If the enemy is in a strongly defended position it is stated that at least 60 will be needed, and this number should be increased to 100 when hostile shelling and bombing are unusually heavy. These mass attacks, say the Japanese, should be directed against weak spots in the opposing lines. There is reason to believe that when they launch such mass attacks they will employ envelopment maneuvers,so favored in their infantry doctrine.
2. INFANTRY SUPPORT.
a. Methods and objectives.
One of the chief factors governing the tactics of tanks is the comparative lightness of their armor and armament. Becasuse of this and their lack of air superiority, tanks are normally employed at night. They are used in small groups of four to six tanks, sometimes even two. One of their main missions has been in support of infantry in attacks on defended perimeters. They have also been used to support infantry in attacks on road blocks.
These attacks sometimes follwo a heavy artillery barrage. On one occassion, five tanks were attached to a small task force containing all arms with the mission of following an Allied withdrawal. At the same time, the main Japanese attacking force attempted a wide outflanking movement.
b. Division attack.
Tank attacks of division strength, according to Japanese manuals, will have a front of about 2,700 yards and will employ three tank regiments with a total of approximately 135 tanks. The tanks are committed in three echelons. Two infantry regiments are deployed in the front line, with one tank company deployed considerably in advance of each of them. The mission of the first tank echelon is to neutralize enemy antitank weapons and strongpoints to clear a path for the second echelon.
The latter is deployed immediately in front of the main body of assault infantry, usually with one tank company in front of each of four infantry battalions. The tanks move about 400 to 500 yards behind the first echelon, covering the infantry and paying special attention to hostile automatic weapons. If the situation demands such a course the second echelon may leapfrog the first. The third, or reserve, echelon is used for exploitation or reinforcement of such second echelon units as may require aid.
c. Close support of infantry.
When the support of the infantry by the tanks must be exceptionally close, the tanks are allocated to two combat units. The first combat unit is divided into left and right formations, each of which is preceeded by a patrol of light tanks to locate the hostile position and draw the fire of antitank weapons. Both the formation of the first combat unit consists of four tank platoons, drawn up in two columns of equal strength.
The two forward platoons advance with the infantry, while the two rear platoons swing around the flanks to engage enemy antitank weapons as their location is disclosed. The second combat unit consists of two platoons assigned to liquidate hostile automatic weapons that survive the first echelon. The unit also holds a reserve to provide reinforcements or to exploit success.
3. TANK-VERSUS-TANK OPERATIONS.
The Japanese, so far, have avoided, whenever possible, a clash with Allied tanks, although their doctrine states that the tank is the only ground weapon fully capable of dealing with tanks. One of the few such engagements occurred in Burma when British tanks made contact with the Japanese in a jungle clearing. Six British Lee tanks, three Bren armored carriers, and one company of infantry were ambushed by seven Japanese light tanks and supporting infantry concealed at the edge of the clearing.
As the first Lee tank approached, the Japanese tanks opened up at almost point blank range, knocking out one of the British tanks. The remaining Lees were ordered to move behind the enemy positions. Thereupon, the Japanese tanks tried to pull out and virtually charged the Lees which were blocking their line of withdrawal. Four of the enemy tanks were knocked out by 75-mm and 37-mm fire; one was captured practically intact, and the other two escaped.
4. TANKS ON THE DEFFENSIVE.
In defense the Japanese normally employ tanks to remedy their deficiency in antitank guns and to strengthten the firepower of their infantry. They appear to have little conception of mobile defense or of the use of tanks for immediate or deliberate counterattack. On occasions the tanks have been dug in and became nothing more than pillboxes. In a few cases they have been employed to strengthen the fire power of a light infantry screen covering a withdrawal.
5. COMMENT.
In general, both offensive and defensive employment of Japanese armor has lacked initiative, and losses out of all proportion to results obtained have been incurred. In some cases, the medthods of employment are forced upon the Japanese bu the lightness of their tank armoe. They are aware of these defects, and future developments may permit them to deploy tanks in a more orthodox manner.
1. GENERAL.
Although the Japanese themselves have not used tanks extensively they are fully aware of the effectiveness of armor in the attack, and have developed their antitank warfare to a high level. Protection against tanks is a keynote of their whole defensive system. The apparent shortage of antitank artillery in their formations has forced them to improvise and put into use many unorthodox tactics. These methods they combine with normal antitank activity.
2. ANTITANK MINES.
Where Allied units are known to have tanks, the laying of mines is considered the most essential duty of the Japanese divisional engineer regiment. In one particular operation involving a division it is known that 12,000 mines were laid. Past use of mines by the enemy has shown that they are most likely to be used in the following places:
a. Beaches.
Mines are used on beaches in one or more of the following cases:
- That section of the beach lying between high tide and low tide levels.
- At the edge of high tide level.
- The area from 25 to 30 yards inalns.
Usually mines are laid in rows, with rows from a few feet to 10 yards between them. Individual mines in a particular row may be spaced from 10 to 30 feet apart.
b. Open fields.
Mines are frequently found in large open fields or in the area that may be termed the approaches to the field. Their employment in most cases is the same as employed inland from the beach. They will be placed in rows, and the mines may be expected to be spaced regularly in the row.
c. Roads.
Ordinarily, junctions of roads and approaches to bridges will be most frequently mined. Special care should be exercised to ensure that shoulders of each road are free from mines before the road is used extensively.
d. Cities.
The cities taken by the Allies have yielded many Japanese mines. The location seems to follow the general rule applied to mines found along roads. More mines were found in the centerof the city streets than on open roads; street intersections and shoulders were frequently mined. Entrances leading into official buildings and parks were also mined.
e. Pillboxes.
Because of the characteristics of pillboxes their field of fire is necessarily limited. Therefore, land mines are sometimes used to cover the approaches bordering the field of fire from a pillbox.
f. Approached to obstacles.
Approached to antitank barricades and detours around them are likely to be mined and covered with fire from neighboring positions.
g. Methods of laying.
The mine either is laid on top of the ground or buried so that the fuze is at ground level or one half inch below. The Type 93 (1933) mine, which is normally used, does not always damage the track of a medium tank sufficiently to disable it. The Japanese, therefore, generally lay one mine on top of another or placebooster charges
Figure 5. Examples of proposed Japanese minefield patterns. |
under a mine.
In most fighting areas there has been a total lack of uniformity as to pattern, even in fields laid by troops in the same command,
In fact, many fields had no pattern, and apparently had been placed by troops ignorant of the tactics of mine fields. A document
secured in the latter part of 1944 set forth the principles of mine laying. The patterns which it advocated may be encountered by
our troops in future operations, and are shown in Figure 5.
3. OBSTACLES. Given time, teh Japanese always will construct antitank obstacles around a defensive position. These are in the form of ditches and barricades, invariably covered with antitank and small arms fire. The obstacles are so sited as to supplement natural antitank barriers and are primarily constructed from material at hand. Some typical obstacles so far encountered are illustrated in the chapter on fortifications. 4. ANTITANK GUNS. The most effective antitank gun in the Japanese Army is their Type 1 (1941) 47-mm weapon, which appears to be gradually replacing the older 37-mm model. In addition, they have a 20-mm dual purpose automatic cannon. The bulk of the antitank guns allotted to a position are sited as far forward as possible, in well concealed positions. Alternative positions are prepared, so that the guns can be moved frequently, thus making the spotting of them extremely difficult. They normally are sited to fire from the flanks on the most likely avenues of approach. In close terrain, the Japanese antitank gunner holds his fire until the range is really favorable to him, often waiting until a tank approaches to wthin 50 yards. |
Other artillery pieces of larger caliber have also been used by the enemy to counter tank attacks. The 70-mm battalion and 75-mm regimental guns and howitzers have been employed to cover road blocks, antitank obstacles, and minefields. Antiaircraft guns are frequently sited so that they can engage tanks.
5. TANK FIGHTERS.
The Japanese put unusual stree on close quarter attacks against tanks by individuals or small groups, known as "tank fighters". These groups, in most cases, consist of two or three men. The various weapons they have employed include:
- Armor piercing magnetized mines.
- Mines tied to grenades.
- Clusters of grenades.
- Molotov cocktails.
- Pole mines.
Frequently, a group will operate with a combination of these weapons. Two new, one man attack methods have been encountered recently, which ensure that the attacker does not return if his attack is successful. One of these is the "lunge mine" method, in which an armor piercing charge on the end of a pole is used. The attacker waits in hiding and lunges at a tank with his mine when one approaches. The mine explodes on contact. In the other method, a Japanese soldier has explosive charges strapped to his back. When an opportunity occurs he throws himself under a tank, the charges again exploding on contact.
6. LARGE SCALE ANTITANK DEFENSE.
To combat tanks on a large scale, the Japanese have devised what they call an "elstic defense" ( dansei bogyo ) which operates as follows:
At the approach of a tank attack in force, only some 20 percent of available heavy infantry weapons are used from front line positions. With the exception of one squad per platoon, all units fall back 800 to 1,500 yards. The squads remaining on the front line scatter, lay a smoke screen, and attack the tanks with incendiary grenades as they come through the smoke.
Whuile the tanks are meeting this resistance, they come under the fire of all the main Japanese antitank weapons, sited 500 to 800 yards to the rear. Meanwhile, the divisional artillery moves forward to positions which permit direct firing on the tanks, thus supporting the infantry either in defense or in a counterattack.
Japanese sources state that once a tank attack is stopped by this "elastic defense" methods, the hostile forces are pinched off. The Japanese infantry, although scattered, can still offer successful opposition to hostile infantry which might attempt to exploit the advance of tanks.
An official Japanese Army source states: "Tanks must be defeated at all costs". It is apparent that this is the attitude of all Japanese units, and the employment of suicide tactics against tanks will increase until such time as the Japanese higher command increases the number of antitank guns within units. These suicide tactics may include those types of attack already familiar, together with more original methods.
1. BASIC DOCTRINE AND PRACTICE.
The offensive principles that so completely characterized Japanese infantry doctrine have their corollary in artillery tactics. The primary function of Japanese field artillery is conceived as the immediate and close support of infantry assault. speed of maneuver and constant endeavour to achieve surprise, believed essaential in infantry tactics, apply with equal validity to Japanese artillery doctrine. Other important artillery missions are recognized, but in practice the importance given the close support mission has led to incorporation of artillery with infantry to a degree that would be considered excessive in other armies.
Insistence upon the necessity of keeping artillery well forward in support of advancing infantry is almost as strong among Japanese artillery officers as among those of the infantry. Thorough artillery preparation is recognized in theory as a prerequisite for successful infantry attack. Inadequate Japanese artillery preparation can be charged to a confidence in the self sufficient of the infantry, a lack of appreciation of massed fire, the necessity of a considerable prior registration, and, in many instances, a lack of ammunition. Concentrations have been weak both in duration and intensity, and counterbattery has been poor. To a large extent, artillery raiding parties are relied upon to combat hostile artillery. Traditional reliance upon infantry against modern opponents is too ineffective and costly to escape the notice of the Japanese High Command. Efforts are being made to augment fire support in offensive operations, and increasing stress is being laid upon the need for effective counterbattery fire. However, the tactics of the artillery units so far encountered are not up to the theories laid down by the high command.
2. EMPLOYMENT OF ARTILLERY IN THE OFFENSIVE.
a. Artillery with adcanced guard.
Artillery with the advanced guard usually leapfrogs form position to position behind the infantry component. the movement is made simultaneously if the situation permits. Its promary mission is to give close support to the infantry, but it may also be used to interdict or harass enemy columns. In theory, it even may be used for limited counterbattery against wrtillery pieces and to silence heavy machine guns. This artillery is supposed to bring fire on targets at the maximum possible ranges, but in practice the longest range is about 5,500 yards probably because of the diffuculties of visual observation beyond this distance. With the completion of its duties with the advance guard, the artillery unit reverts to the control of the division artillery officer, or to the infantry commander if attached to a unit of that arm. This change of control is to be made in sufficient time for the former advance guard artillery to coordinate effectively in the main attack.
b. Selection of positions.
Another duty of the Japanese advance guard artillery is the selection of positions and observation posts for the unit artillery. Consideration also is given to the location of areas for the unit trains and to routes of advanceand resupply to the positions chosen.
The tactical principles of Japanese artillery dictate the choice of positions certainly located in the rear of the attacking infantry. (An exception to this dictum is made in jungle warfare as is discussed in part II). The positions usually are chosen as far forward as it is possible to obtain the necessary concealment. They are selected to permit the concentration of fire on the area of the main attack, yet to allow a considerable shift in direction of fire if changes in the situation require. Such locations also enable the artillery to give closer and more direct support to the infantry. The favorite location for positions, is a gentle reverse slope, preferably in a wooded area. Alternate positions are selected in advance of whenever this can be done.
If a new position is to be taken, ammunition is stockpiled there is possible, but at all events the ammunition supply is replenished before th emove is made. The Japanese site observation posts well forward and uses the observers boldly, often sending them well ahead of their forward positions and relying on their mobility for their protection. Fire is adjusted from observation posts in a normal manner, using battery commander's scopes, aiming circles range finders, and field glasses. Especially with infantry guns, the observation posts usually are located within voice range of the gun positions.
They are placed as close as possible to the gun target line because the small T method of adjustment apparently is preferred. Air observation has not been used, probably because of lack of air strength rather than because of lack of appreciation of its value as training in its use is given at the artillery school.
Guns are normally sited in single gun positions, though sometimes sections of two guns are emplaced together. When battery positions are used, the guns are sited with one gun behind the other (about 100 to 200 yards apart) down teh gun target line. positions are rarely at right angles to this line. sniping and roving guns are used extensively, though they usually are attached to infantry units. All guns are well dug in and camouflaged. Dummy positions, established in practically all situations, are considered by the Japanese to be one of the most effective defenses against counterbattery fire.
When more than one gun is employed in a single position, the Japanese often mix calibers, so that one 105-mm guns and one 150-mm howitzer may be firing from the same location. Battery firing positions have been known to be arranged in squares. Two guns constitute a section, and the pieces of each section are sited one behind the other. One section fires its guns alternatively at one tartget, while the other section does likewise on another target. These guns may also cover medium artillery registered on the same target and sited in depth down the gun target line.
Japanese artillery communications depend mainly on wire telephone circuits, supplemented by other signal means,except radio which has not been used by the units so far encountered (1944).
c. Fire plans,
Since the Japanese think of artillery as a weapon for direct infantry support, their fires are usually confined to prearranged infantry support tasks. This is evidenced by their ignoring many targets of opportunity upon which heavy casualties and considerable disorganization could have been inflicted. such oversight is explained partly by the Japanese inability to transfer fires rapidly from one target to another and partly because the new targets were not included in the original plan, and had no direct bearing on the immediate operation.
The Japanese seldom have used mass fires nor have they fired cocentrations in the manner of Allied artillery. Until very recent operations in Burma, they had not been known to fire more than six guns at one target at one time. The Japanese apparently conceded the superiority of Allied artillery for they used several passive measures to protect their guns. Fire was delivered at night only when support was required for an infantry attack. Such fire seldom lasted for more than 1 hour and ceased immediately if Allied planes appeared over the area of the gun positions.
Japanese guns usually cease fire during the day or at night if Allied planes are overloaded, but exceptions to this have been noted recently. To avoid detection by Allied sound and flash ranging units the Japanese resort to such countermeasures as firing several calibers from widely separated localities, firung alternatively from two locations during registration, employing small caliber artillery covering fire for medium weapons, simulating sound and flash from positions forward of the true location of the firing pieces, and moving to new positions after each fire mission. Medium artillery often is emplaced so far to the rear as to be beyond the range of Allied light artillery and only within the extreme range of medium weapons.
d. Accuracy and effect of fire.
Although accuracy and effect of their fire are good, in nearly all operations the Japanese have neither concentrated nor massed fires. Instead of guns against a single target in a short period of time, they place fire from a very few guns slowly, though accurately, on the one target. In a recent operation, however, they have shown an ability to concentrate fire from a large number of weapons of all calibers on one target area from widely separated positions.
Ammunitions is not wasted, and the weapons are quite accurate when obeserved fire can be used and sufficient time is available for registration. The zone of dispersion for medium weapons is small; the effect of individual rounds is quite comparable to Allied rounds, and teh fragmentation of shells is good.
e. Artillery in the meeting engagement.
In the meeting engagement, the Japanese artillery is used mainly in the meeting engagement, the Japanese artillery is used mainly in direct support of the infantry. The artillery is attached direclty to the infantry, particularly where the front is wide, liason is diffcult to maintain, the terrain is broken and wooded, or combat begins unexpectedly. Japanese doctrine indicates that ideally the artillery in the meeting engagement should be under the command of the division artillery commander, but this does not seem to be carried out often in practice.
The missions during the deployment for the attack are the same as during advance to contact. Once the attack begins, fire is shifted to hostile infantry reserves, as well as to enemy artillery, though the prime emphasis is on the direct support of the infantry. In the final phase of the assault, the Japanese expect to concentrate their fire in the area of decisive importance and to interdict routes available for the forward movement of enemy reserves.
f. Artillery in the attack of a position.
In the attack of a strongly held position, the Japanese doctrine calls for the reinforcement of the divisional artillery by battalions of light and medium artillery. Almost always, the artillery is assigned direct support missions, none being held in general support. Some of the reinforcing artillery may be used for counterbattery work, but that mission usually is reserved for the artillery under army control.
Some attempt appears to have been made by high Japanese commanders to increase the flexibility with which the guns are employed and to ensure the centralization of command on which modern performance depends. But, in actual operations these two requirements have been almost completely lacking except in the most recent fighting around mandalay and, perhaps, in teh defense of Iwo Jima.
The attack of a position usually is made at night, in which event the artillery completes its registration during the previous day. An attack in daylight occurs, in theory, 1 or 2 hours after dawn which allows the artillery time to register by daylight prior to the attack. The first phase of the attack is aimed at the outpost line, and the larger part of the artillery is placed on the flank where the main effort is to be made.
The remainder is assigned to the area of the holding attack. some of the guns may be given counterbattery missions during this time, although lack of artillery has often forced the total neglect of this mission so far as the guns are concerned. When the outpost line has been taken, the artillery shifts to counterbattery, interdiction, and harrasing fires until the scheduled time for the beginning of the artillery preparation has arrived. The total period usually assigned for firing a preparation is 1 to 2 hours. Of the fire laid down, about one third is devoted to each of these tasks:
1) Ranging.
2) Obstacle destruction and wire cutting.
3) Neutralization fire against enemy infantry positions, including fixed fortifications.
This allows no fire to be brought against the enemy's positions in depth, while teo thirds of the fire is directed against highly unremunerative targets. When the attack begins, the mission of the artillery changes to one of direct support with special attention to the area of the main effort, usually one of both flanks of the enemy position.
The possibility of dawn attacks should increase as the enemy perfects his technique of night survey and more rapid daylight registration. This apparently has received much consideration from Japanese authorities and the possibilities of such attacks are becoming more and more likely, granted sufficient personnel and materiel are available. Observation posts are pushed farther forward, if the guns cannot be moved, to compensate for the difficulties of night observation and registration.
g. Artilleryu in night attacks.
Night attacks in force are distinguished in Japanese doctrine from the more favored night attcks by surprise. Only in attacks in force is there any artillery preparation. The artillery in this type of attack is expected to fire on designated target areas upon infantry rocket signal. Special consideration also is given to fire missions that will limit the enemy's ability to counterattack decisively. The Japanese believe that artillery in support of a night attack should be kept as mobile as possible, and excessive rigidity in formulating fire plans is condemned. This is a particularly strange doctrine because carefuk prior planning is necessary to insure that concentrations are delivered in critical areas and that friendly troops ae not endangered by the bursts. Artillery fire is used in night attacks as an aid to the maintenance of direction.
h. Artillery in the pursuit.
As soon as it is discovered that the enemy is withdrawing the Japanese attach most of the artillery to forward infantry regiments to facilitate coordination and rapid liquidation of enemy covering positions. The general mission of the artillery is to disrupt the enemy's retreat by interdicting junctions and bottlenecks in the road net, bridges, defiles, etc.
As the pursuing infantry penetrates the enemy covering positions, the attached artillery follows it by bounds and, when necessary, concentrates its fire on resisting enemy infantry. Battery commanders are directed to retain the ability to occupy firing positions quickly, and teh line of command is kept as direct as possible. It also is held to be advantageous in pursuit operations to fire on the enemy's flanks wherever possible, and to conduct vigorous reconnaissance in order that successive firing positions will be in readiness as the pursuit continues. Routes of advance to these new positions of course must be prescribed and carefully concealed from the enemy.
i. Critique of Japanese artillery employment in the offensive.
There are many weaknesses in the Japanese artillery technique and employment in the offensive, of which most fundamental is the primitive state of development of the doctrine on which their artillery performance rests. The most obvious results of this faulty doctrine have been:
(1) Lack of massed fires.
(2) The failure to fire on suitable targets.
(3) The mixing of different calibers and types of artillery in a single battery.
(4) The lack of sufficient pieces of all types.
(5) The inordinate length of time required for registration.
(6) The long period required for the transfer of fires.
(7) The lack of a fire derection center.
(8) The absence of technical means of counterbattery intelligence.
(9) Failure to consider countermortar and counterflak fire.
(10) Lack of appreciation of modern methods of planning the use of artillery, both in relation to other arms and in its internal arrangements.
(11) Failure to consider calibration of pieces and the preparation of tables to correct for wear.
(12) onsiderable confusion as to the requirements of neutralization fire. Specifically, the weakness of Japanese artillery in the division makes it unable to carry out the assignments normally given to such a unitif any offensive mission against a modern opponent.
For example, unless the organic artillery is more strongly reinforced than is likely, it does not have the strength to carry out the basic mission of neutralization of the enemy's defenses prior to the attack. No real neutralization of a strongly dug in position can be achieved by divisional artillery that contains three battalions of light and one battalion of medium artillery. Even in a strengthened division, the organic artillery is incapable of furnishing the volume of fire needed in the attack.
Further, the usual dispersion of the pieces of artillery among various infantry commands reduce the efficiency of the artillery and makes it almost inflexible in its operations. However, in the Japanese army, the necessity of a more modern approach to artillery practice is recognized, and each successive operation should find Japanese guns better prepared for offensive assignments.
There seems to be little question but that Japanese artillery will be more effective in the future, particularly in concentrtaion of fire , flexibility of operation, centralization of command, and availability of ammunition. The establishment of a fire direction center is not to be anticipated from any information yet received. In fact, the idea appears strange to all Japanese artillery officers, even those of the highest rank, though it may be that they understand it but feel that the average Japanese artilleryman does not have sufficient training to operate a fire direction center.
3. EMPLOYMENT OF ARTILLERY IN THE DEFENSIVE.
a. Location of positions.
In the defense of a position the Japanese realize the need for artillery support for the defense of the outpost line. A relatively small part of it is placed forward of the main line of resistance; most of it is emplaced behind it. The primary considerations in the siting of the artillery usually are its use as support for the infantry zone resistance through the use of limited normal barrage and concentrations and the development of effective coordination of fire of the two arms. On occasion, the artillery may be sited within the infantry positions, but, if this is done, every precaution os taken to avoid diminishing the fields of fire of the pieces.
Observation posts usually are behind the infantry positions, although observation posts within those areas are used when the situatio requires. Alternate or switch positions are prepared, since normal practice is to shift all pieces after the firing of each mission. The batteries generally are echeloned in depth from 1,700 to 2,200 yards behind the main line of resistance. Positions are chosen to facilitate effective interdiction fire at extreme ranges, but the guns are so sited as to make possible their immediate shift to direct support of the defending infantry without change of position. In an area in which the enemy has a preponderance of artillery, the Japanese may site their medium weapons in considerable depth, beyond the range of all light and much medium artillery of the Allies. This limits the depth of the enemy position that can be brought under fire but effectively prevents counterbattery fire against the Japanese pieces. simulated sound and flash is used to prevent or limit direction of actual pieces.
b. Responsibilities of unit and artillery commanders.
The Japanese division commander on a defensive mission prescribes the direction of fire of the artillery, designates the most vital sectors of the main defense line, and selects in general thet areas in which the artillery is to be emplaced best to support the infantry plan of defense. He also fixes the time at which fire for adjustment will be undertaken, and the time and rate of fire for effect. On receipt of these instructions, the artillery commander issued orders for the deployment of the division artillery and assigns definite missions to the main subordinate units. He also prescribes the type and method of fire which include the locations of areas of concentrations and limited normal barrages, the ammunition to be used, and the priority of targets.
c. Conduct of fire.
On the defense, Japanese tactical doctrine directs that the artillery place its largest volume of fire on the area between the main line of resistance and the defensive positions on the outpost line or on the advance defense position. The greatest concentrations are fired in front of, and subsequently within, the network of infantry fire from the main line of resistance; artillery commanders are told to retain the capability to bring fire within the main battle position as well.
The densest fire is planned in the area through which the main enemy attack is expected to pass. Nevertheless, in addition, considerations is given to siting of the artillery to support counterattacks against likely enemy penetrations of the main battle position.
Japanese defensive artillery first delivers interdiction fire against routes of approach of enemy units and probable assembly areas. This interdiction fire is followed by a limited barrage as the enemy approaches the main line of resistance. From the viewpoint of modern artillery practice it is surprising that relatively few of the available pieces are committed until the enemy is within close range. However, the Japanese feel it better to conceal the strength and position of their artillery than to expose it to counterbattery. Such methods of fire are contrary to accepted principles but also agree with the Japanese emphasis on destruction of the enemy in close combat.
Counterbattery is avoided during this period, and enemy counterbattery is opposed by a frequent shifting of the position of the pieces engaged . The artillery must be prepared to assume an antitank role as conditions require, not only to protect the artillery itself but also to aid the infantry in maintaining their positions against tank attack.
d. Ground units in counterbattery operations.
The limited quantity of Japanese artillery greatly restricts the missions that can be fired by it, and the one usually neglected is counterbattery. The Japanese, however, understand thoroughly the need for destruction of enemy artillery and, since they cannot destroy it by fire, attempt to destroy it by raiding units. These infiltrate through the enemy lines and attempt to reach the actual pieces to render them useless by placing explosive charges on one or more of their vital parts.
Such raiding units often, though not necessarily, are suicidel. Their organizations are quite flexible and are adapted to the types of weapons to be attacked and the terrain to be crossed. Such tactics naturally are more feasible in the jungle than in other types of country.
e. Critique of Japanese artillery employment in the defensive.
In defensive operations so far conducted, Japanese artillery has been poorly used, partly because of a lack of weapons and of ammunition but also because of the fundamental doctrine that govern its use. Fires of all types are delivered far too slowly by an inadequate number of guns and, apparently, with little consideration given to the requirements in ammunition for the reduction or neutralization of the target in question.
The use of survey methods has been difficult in the areas in which the Japanese have been fighting, but even the surveying of the gun positions of a single battery in relation to each other has been neglected. As a result, the adjustment of fire has been done usually by each piece separately. This practice has increased ammunition consumption and has made adjustment particularly difficult when more than one gun was firing on the same target. The tendency to hold artillery in reserve has reduced the potential power of Japanese fire. Althuogh a lack of ammunition and a fear of counterbattery fire have been responsible for this in some instances, a basic bias against a non-firing reserve is usually the cause. Japanese artillery has improved in effectiveness in the most recent operations.
To a large extent this improvement can be explained by an increase in available guns and ammunition, but definite instances of the handling of artillery in a modern manner have been noted and are likely to increase as the Allies come closer to the Japanese home islands.
4. EMPLOYMENT OF ARTILLERY IN DELAYING AND WITHDRAWLS.
In a delaying action, the Japanese artillery takes the enemy under fire at extreme ranges from positions close behind the infantry forming the covering force. In contradistinction to the usual practice, the pieces are grouped closely by battery and battalion for ease in control and direction of fire, for the Japanese believe that the danger pf enemy counterbattery is relatively small in such operations. A portion of the available artillery is kept in reserve at some distance behind the position as the base of fire for the next line of defense. When the delaying forces move back from one delaying position to the next, this artillery has the mission of covering that withdrawal.
In Japanese doctrine, the daylight withdrawal is not looked upon with the disfavor that it finds in other armies, and such an action makes a heavy call on their artillery. The division reserve is usually committed as the covering force, and the division artillery is deployed behind the covering position to aid in protecting the withdrawal. In a night withdrawal, the Japanese do not organize a covering position but instead leave behind a number of small detachments, heavily equipped with automatic weapons to form a covering "shell".
Only a small part of the unit artillery is assigned to the covering "shell", and both the infantry detachments and the artillery are expected to sacrifice themselves, if necessary, to cover the retirement of the main body. Normally, the artillery remains in position until nearly dawn and then is withdrawn to the control of the main body.
5. EMPLOYMENT OF ARTILLERY IN RETREAT.
In a full scale retreat, only a relatively small portion of the Japanese artillery is used with the rear guard; the rest attempts to withdraw along covered rouutes. Such artillery as is employed is placed near the flanks of the retiring force do that it can fire until the pursuer is quite close without endangering the retreating Japanese.
6. EMPLOYMENT OF MORTARS.
The Japanese have exploited thoroughly the capabilities of the mortar, particularly in their jungle operations. For every close support of the infantry they have relied on the 50-mm grenade discharger which they have used with considerable accuracy and effect. However, this weapon does not have the requisite range and effect to provide the needed base of fire for the infantry. Therefore, larger weapons have been used to provide the fire power needed by ground units.
In the attack, mortars are used well forward to neutralize defended localities that are holding up the advance, which cannot be engaged by machine guns, and for which artillery is not available or pehaps even suitable. They also are employed to replace artillery in areas to which even the light Japanese artillery pieces cannot go. The methods of employment of mortars are quite similar to those of most Allied armies, with emphasis on the close support role of the weapons; little consideration is given to their employment in large numbers to provide massed fires. Rather they are used primarily to supplement the other heavy weapons of the infantry unit. The larger mortars are used in the main to provide additional fire power for the unit artillery and are givem missions normally assigned to artillery. They, as well as the artillery, are seldom fired with modern methods of fire control.
In the defense, mortars are employed against probable avenues of approach and against assembly areas. If the forward Japanese positions are overrun but still occupied , mortar fire often is brought down on their own pillboxes and shelters on which the mortars were ranged in advance. Such methods are not likely to injure Japanese troops within the positions and are almost certain to place fire among or near attacking Allied troops. As is true of their artillery, the Japanese usually move their mortars frequently to alternate positions established well in advanced of the need for them.
Japanese methods of mortar fire control are based on the use of an observer (usually an officer) who takes a position close to the gun target line and who estimates ranges with the help of field glasses rather than by the use of any of the more complicated types of range finders. Orders are transmitted by field telephone of, if the observer is close enough, by visual signal. one rather novel method of target indication has been the firing of intersecting streams of tracers over a target that could not be reached or properly engaged by machine guns. The observer then directed mortar fire on the point where the tracers crossed within a few seconds after machine gun fire was opened.
Mortar fire is usually brought down on Allied troops during the firing of an Allied barrage to give the impression that at least some of the pieces are firing short.
The tactical use of both types of Japanese mortar units seems to be much the same, though they may be designed as either infantry or artillery mortar units. In most front line work the mortars are assigned to the direct command of the immediate infantry commander, who is responsible for their employment. However, when large mortars are used, or when they replace all or part of the divisional artillery, they may well be held under the direct control of the artillery commander.
As operations shift from the jungle to more open types of terrain, the Japanese use of mortars to replace and supplement field artillery will be less and less feasible. This is mainly because of the greater displacement in depth that will be required of all arms in areas where concealment is far less available. The shorter range of the majority of Japanese mortars will prohibit their use from positions at any great distance (over 1,000 yards) behind the main battle positions.
1. GENERAL.
Japanese antiaircraft measures are both passive and active. Within the capabilities of their weapons the Japanese have achieved a fair degree of success. Little tactical change has been observed on the island campaigns thus far; the developments noted have been in the nature of improvisations rather than fundamental changes in doctrine. On the Japanese mainland, however, a radical departure from earlier tactics has recently been observed.
In the earlier stages of the war, decentralization in the control of antiaircraft batteries was common. This was probably dictated by shortages of equipment and the desire to achieve a maximum of protection with the materiel available. Six gun units were often subdivided into three two gun batteries.
In a recent observationof an antiaircraft installation in Japan it was noted that a concentration of four individual batteries has been made, but, instead of combining all of the guns into one intrgrated battery defense, individual battery organization was retained. Weapons of different calibers appear to make up this "master" site so that fire control data probably will have to be computed by the individual battery. A gun laying radar is included in this new antiaircraft defense system. This is in addition to a probable searchlight and radar combination. The Japanese, in their defense of vital homeland installations, will be able to deliver a greater concentration of fire by this new battery arrangement with a probable increased efficiency in operational control.
2. MISSIONS OF ANTIAIRCRAFT ARTILLERY.
The primary mission of Japanese antiaircraft artillery is the defense of vital areas and installations against attack by enemy aircraft. In the assignment of priority areas to be defended, the Japanese follow the same tactical consideration which governs the employment of antiaircraft artillery in other armies.
Japanese antiaircraft artillery is often sited so that it can be used in the role of field artillery. This is specially true in the widespread use by the army of navy dual purpose weapons such as the 120-mm and 127-mm dual purpose guns. On Saipan, twin mounted 25-mm guns were found on steel sleds with towing rings for movement from position to position.
3. WARNING SYSTEMS.
In order to obtain an early warning of the approach of hostile aircraft, the Japanese employ the conventional agencies and methods. Radar is generally used in all important defense systems. Some of teh sets are capable of more than 60 miles range, but as a general rule the Japanese have not achieved great proficiency in radar development.
Outposts, employing visual observation, are used extensively to alert guns and searchlights. These have been located on outlyign islands or on such terrain features where they can obtain the earliest warning possible. Readio and telephone are used for communication, and teh observer is generally equipped with binoculars for observation purposes. In other instances, the gun crew act as air guards and endeavor to obtain their own advance notice of impending raids.
As the war approaches the Japanese homeland, there is evidence that warning systems will be more elaborate than previously encountered. In important areas of Japan there appears to be a well organized aircraft early warning system, supplemented by a close coordination of antiaircraftartillery, searchlights, and fighter planes. In one vital area in Japan, information is disseminated, simultaneously, to all defense units, down to and including antiaircraft battery headquarters.
Telephone and wireless communications systems have been installed to expedite early warning which comes from observation posts and radar statons which apparently report into a central defense headquarters.
4. PASSIVE DEFENSE MEASURES.
Passive antiaircraft meaures used by the Japanese include the construction and use of dummy positions and camouflage. By these means and attempt is made to conceal the defended area from aerial observation, to make it appear as a non military objective, or to draw fire of the attacking aircraft. Camouflage encountered, to date, has generally been good as far as the smaller installations have been concerned, but attempts at the concealment of large targets have not been particularly successful.
The Japanese mayu be expected to exploit more fully these attempts at deception, with dummy guns, camouflage, and frequent movement of weapons to alternate positions - this latter measure has already been extensively employed.
5. ACTIVE DEFENSE MEASURES.
a. Weapons.
Antiaircraft weapons of caliber ranging from 6.5-mm light machine gun to the 127-mm (Navy) gun are known to be in use by the Japanese army in their active antiaircraft defense systems. Their high velocity weapons have estimated effective ratings up to 27,000 feet. These weapons are used to destroy attacking aircraft or to cause them to abandon their mission. Ammunition used by the Japanese includes ball, incendiary, and high explosive fragmentation projectiles with powder train and mechanical fuzes.
b. Barrage balloons.
These have been employed as protection against hostile aircraft. When used near water areas, the balloons are usually painted a greenish blue making them difficult to detect. In some localities of Japan proper, barrage balloons have been flown at altitudes ranging uo to 4,000 feet.
c. Night fighter planes.
In conjunction with antiaircraft ground defenses, night fighters have been used but without much success. In one defended area, the zones of the night fighter were limited to areas outside the firing radius of the antiaircraft guns. The artillery ceases fire, however, when the hostile plane is pursued by the Japanese night fighter in the area of gun operations. The night fighters generally patrol on the other fringe of the searchlight ring. There is some evidence that night fighter planes are equipped with radar.
d. Other measures.
The Japanese recently have begun to employ a variety of improvisations to supplement their antiaircraft defense systems. Among these weapons are aerial burst bombs. Such bombs, equipped with impact and time fuzes, can be used against airborne or grounded aircraft. The cluster bomb is one type and is packed 76 bombs to the cluster which opens shortly after leaving the releasing plane. After a drop of a few hundred feet, the individual bombs scatter, with detonation occurring as the separate bombs hit the target.
The air-to-air parachute bomb is another device reported in use. Thi sweapon consists of a small bomb attached to a 150 foot cable. Two small parachutes are attached to the other end of the cable. Antiaircraft striking any portion of teh cable will cause a detonation of the bomb. The cable also presents an incidental propeller fouling hazard.
An innovation in Japanese defense against low flying aircraft is the aerial burst 81-mm mortar shell. While in flight, the projectile is held by a small parachute. The shell explodes when the parachute shrouds are struck or by a self destroying element in the fuze.
The Japanese have begun to use the 75-mm mountain gun as an antiaircraft weapon. Emplaced in such a manner as to allow an increase in elevation, the gun is used against low flying aircraft on strafing or low level missions.
Antistrafing wires and cables have been frequently reported strung across narrow valleys, between trees, and across rivers. This type of obstacle has been suspended from levels between 30 and 100 feet.
The extent of these antiaircraft artillery substitutes can best be illustrated by the reported use of land mines against low flying aircraft. The mine apparently is exploded by a remote control mechanism as the plane passes over the mined area.
e. Train mounted defenses.
The Japanese have mounted antiaircraft weapons on railroad trains in order to furnish protection against low level bombing and strafing. In Burma, one car, mounting four to six machine guns and from two to four 20-mm guns, was attached to railroad trains. in China, antiaircraft artillery has been reported as being carried on teh car immediately behind the locomotive.
6. EMPLACEMENT OF ANTIAIRCRAFT ARTILLERY.
Japanese antiaircraft artillery is usually emplaced within a 1 mile radius of the defended area. The greatest concentration of weapons occurs between the defended area and the sea approaches thereto, along shore lines, and in the direction of enemy territory. Guns are emplaced in single positions, and in batteries of two to twelve weapons. The distance between guns of both heavy and medium companies varies from 40 to 250 feet.
Machine guns are generally emplaced so as to render close in protection against low flying aircraft. There appears to be a tendency to move antiaircraft defenses farther out from the defended area in order to bring fire to bear on attacking aircraft much sooner, and to allow a longer period of time in which to engage the target.
In general, the arrangement of firing positions is dependent on the number of guns employed and upon terrain conditions. When three guns are used, the position normally takes the form of a triangle, with one gun in each corner and teh command post in the center. In teh case of four guns, a rectangular formation is used . Where more than four guns are used, the position is generally that of a shallow arc. Antiaricraft guns are often emplaced on high ground in order to be capable of a 360 degree traverse.
In one area in Japan, six guns, supplemented by a searchlight and gun laying radar, constituted a standard battery. The emplacements approximately 35 to 55 yards apart, were arranged in a semicircle. Commmand posts and fire control directors were to be located 110 yards from the battery, with searchlights 1,100 to 1,600 yards from the battery position.
7. GUN EMPLACEMENTS.
The most common type of gun emplacement used by the Japanese is of circular or semi-circular construction. These may be constructed level with the ground or slightly dug in. They are surrounded by built up revetments constructed of logs, stone, coral, and sand bags. Entrance to the position is usually protected by a blast wall. a variation of this type of emplacement consists of two concentric circular revetments. Recently, the outer revetment has been made higher than the inner. This type of construction precludes the use of the weapon against terrain targets but affords considerable protection to the gun crew and weapon.
Approximate sizes of emplacements are as follows:
| Weapons | Diameter of emplacement | |
| 105-mm | -------------------- | 25 feet. |
| 75-mm | -------------------- | 15 - 20 feet. |
| Machine cannon | -------------------- | 13 - 15 feet. |
| 13-mm machine gun. | -------------------- | 8 feet. |
8. SEARCHLIGHTS AND FIRE CONTROL MEASURES.
The tactical use of Japanese search lights has seldom approach the proficiency attained by the Allied nations. Searchlight units with accompanying sound locators are usually charged with the task of alerting the gun batteries. Radar has been substituted for acoustical locators in many instances, and Allied aircraft have been picked up as soon as lights were illuminated. The japanese will use as many lights as possiblr to illuminate the target and carry it in the beam until the target is lost.
The beam is extinguished when tracking becomes difficult or the plane eludes the tracking searchlight. While the Japanese understand the use of pick up and carrying lights, they have had considerable difficulty in effecting coordination in these searchlight operations. Searchlights apparently are operated from a central control station and have been used as part of teh night fighter searchlight team. Lights are emplaced in an oval pattern around the defended area, with emplacements, generally revetted, of circular pattern from 15 to 35 feet in diameter.
Fire control instruments such as directors, height finders, and fire control accessories are of rather obsolete design when compared with the equipment of modern armies. Firing data is transmitted orally to the gun crew by operators of carriage fire control instruments. Directors are used with heavy antiaircraft artillery.
Automatic weapons are fired using individual tracer control methods. Often, Japanese planes will fly at the same altitude as the attacking aircraft. The purpose of such tactics is to transmit by radio data as to the elevation and rate of travel of the target. Corrections to antiaircraft fire have been rapid and accurate when teh Japanese employ this improvised type of fire control. Colored spotting rounds are often used to determine deflections in firing.
The barrage type of fire is commonly employed, and there are indications that fuzes are precut and held in readiness for firing when the target approaches the calculated range.
1. DIVISIONAL ENGINEERS.
a. General.
The engineer unit assigned to each Japanese division consists of a regiment of about 960 men. This is somewhat larger than the strength of the engineerr component of the American or British divisions. The equipment assigned to the Japanese divisional engineers, is far less than that issued to the corresponding American unit and somewhat less than that of the British.
Japanese engineers are used in small detachments which are attached to small combat teams, infantry battalions, companies, and even smaller units. This common practice removes the work done by them from the centralized conrol of the division engineer. This is in exact contrast to American and British doctrine which places the engineer component under the direct control of the division engineer as much as possible. The weaknesses of decentralized engineer operations may be less dramatic than those of decentralized artillery but they are just as fatal to the correct functioningof the arm. Duplication of effort and the lack of effective coordination are common results of the attachment of small units of engineers to other arms when the suituation permits centralized engineer control.
The Japanese divisional engineers are primarily pioneers and, as such, are quite similar to the pioneers of the German division, except that they have much less mechanical engineer equipment. In contrast, the British field and field park companies of the division are composed of highly trained technicians, while American engineers occupy a position intermediate between the British and the Germans. The mission assigned to the Japanese engineers is the same as that of like American units, i.e. to facilitate the movemoent of their own troops and to hinder that of the enemy.
b. Missions.
The usual work of the Japanese pioneers appears to be:
(1) Construction and repair of roads, trails, and bridges and the operation of other river crossing means.
(2) Demolitions.
(3) Minefield laying and the construction of other antitank obstacles.
(4) Passage of minefields and removal of other obstacles.
(5) Layout and construction of defensive positions behind the front.
(6) Employment as infantry in emergency .
(7) Engineer services such as map supply.
2. ROADS AND RIVER CROSSINGS.
The Japanese engineers are severly handicapped by a lack of heavy earth moving equipment. As a result, their work on roads or airfields os slower by far than we should accept. The construction or repair of heavy bridges is beyond the scope of Japanese divisional engineers, but they have shown great skill in the use of expedient means of bridge building.
In river crossings some standard equipment isused, principally rubber boats, although several types of assault, ponton, and steel bridges are standard equipment. The amount of river crossing equipment available to the average Japanese force is not comparable to that of similar forces in other armies. In assault crossings of jungle rivers, and for the later repair of bridges over them, the heavier types of river crossing equipage have not been brought in readily.
Japanese engineers therefore have been forced to rely heavily on expedient types of river crossing materiel and bridge construction. Such expedient river crossings have been amde effectively, though none has been made against Allied opposition since the early days of the war. The initial crossing of foot troops ios accomplished on rubber boats and anythign else that will float.
Heavier equipment is ferried until such time as a bridge can be put in or an existing bridge repaired. Short bridges are repaired quickly with local materials and, while these repairs would not serve to carry the heavy equipment of an Allied army, they are quite satisfactory for lighter Japanese materiel. Larger bridges usually are not repaired at all, floating bridges or ferries being substituted for them.
The posisbility of further assault crossings by the Japanese in force is relatively small, but the use of standard or expedient river crossing means may well be necessary in areas in which our aerial superiority has enabled us to damage or destroy the existing bridges.
3. DEMOLITIONS.
Demolitions in Japanese doctrine are treated in much the same manner as in other armies but with more emphasis placed on offensive use. Small raiding parties, armed with relatively small packaged charges and composed entirely or largely of engineer troops, are common.
These units infiltrate Allied lines, with their objectives such vital materiel as artillery pieces, signal installations, supply dumps, gas and oil depots, and large bridges. The defensive use of demolitions in increasing but it is still not effective if judged by European standards. Individual demolitions have been carried out successfully, but the fittingof these into a sound overall plan for the protection of a withdrawal has been consistently lacking. Small parties charged with the execution of prepared demolitions are susceptible to surprise for they do not react quickly to a sudden change in the situation which requires rapid action on their part.
This appears to be true even when the operation to be carried out is the simple one of depressing an exploder or lighting a fuze.
4. MINEFIELDS AND OTHER ANTITANK OBSTACLES.
Until quite recently, Japanese minefields operations were poorly planned and even more poorly executed. In the early days of the war, the Japanese had little use for minefields and encountered relatively few of ours; when the need for mine operations became apparent, they found themselves inexperienced and unprepared. Their general doctrine for employment of minefields is much like ours, but the details of practice had not been worked out and are only now being disseminated to field units. However, in preparations for the defense of Luzon and Iwo Jima, the Japanese made liberal use of mines, employing them in more or less regularly patterned fields, booby trapping them and using improvised mines made from such a variety of materiel as aerial bombs, depth charges, torpedo war heads, and artillery shells.
The first reports of electrically controlled minefields were received from the Philippines.
The Japanese engineers are assigned the job of placing demolitions and appear to have laid a considerable proportions of those encountered so fat. Their technique has left much to be desired (from the Japanese point of view), but it is gradually improving and presumably will continue to do so as further practice and study of the lessons of the European war are carried out.
The construction of the Japanese engineers, although they appear to receive considerable assistance from infantry and labor troops. The types of obstacles made and the tactical use to which they are put are discussed in Section VI on antitank tactics.
5. PASSAGE OF OBSTACLES AND ATTACK OF A POSITION.
The Japanese engineers have not had the opportunity to engage in large scale passage of obstacles and it is not probable that they will. Their basic doctrine is of interest, however in that it will govern small scale offensive actions. In the attack of a position, Japanese divisional engineers are sent forward with the infantry. If they operate as independent assault detachments they vary in size from a squad to a platoon. The detachment is divided into parties. The first of these is the obstacle party which cuts a lane through the wire obstacles encountered. It is armed with bangalore torpedoes, often improvised; smoke candles; grenades; and wire cutters.
The assault party follows the obstacle party and attacks its assigend objective, such as a pillbox. It may be a large as an entire squad and is equipped with one or two flame throwers, bangalore torpedoes, pole charges, grenades, and wire cutters. The support party, armed with machine guns and rifles, backs up the assault party by fire at short range, aiming particularly at embrasures and loopholes, not only of the objective itself but of flanking positions as well. The reserve party furnishes replacements for the assault party, assists in covering it with fire, and mops up the objective.
The reserve also carries additional explosives and hand grenades. In theory at least, the assault is practiced in detail until all members of the team are letter perfect. In an attack by day, the assault party follows the artillery barrage closely or may even work under cover of the preparatory fires. All possible use of terrain is made to avoid small arms fire. The use of gas grenades against pillboxes is discussed, but no confirmed reports of their actual use have been received. If the attack is made by night, reliance is placed entirely on surprise, without artillery preparation in almost all instances. The support party is omitted, and the oher parties are reduced in strength from their daylight equivalents. If mines are laid forward of the position to be assaulted, the removal of those not destroyed by the artillery preparation if fired is a duty of the obstacle party which is reinforced for this work.
6. OTHER DUTIES.
Little is known pf the use made of Japanese engineers in teh layout of defensive positions but, from the excellent character of these installations, it appears that they are well trained for their work. Actual construction of such positions must be carried out, as in the U.S. Army, by the troops who are to occupy them rather than by the engineers.
The use of engineers as infantry is a more common practice than in the U.S. Army, and their use in assault units is more productive of casualties than such U.S. operations. Some of the relative inefficiency of Japanese engineer operations may be accounted for by the high number of replacements needed.
If these are furnished, they will not be as effective as those whose places they take; if they are not, the reduced strength of the unit will be even less able to do its work.
Certain engineer supply functions are given to the divisional engineers, but, beyond the supply of maps, no definite information is available as to how these relate to the needs of other arms and services. The supply of water is not a function of the engineers, as in the U.S. Army, but belongs to the water puriofication unit which is under a division medical officer.
7. NON-DIVISIONAL ENGINEERS.
The divisional engineers in the Japanese army ar kept so far forward in the advance as to preclude completion of all the work they begin. It is probable that, as in the U.S. Army, the engineers of the higher echelon take over the jobs as the division moves forward. In teh Japanese Army, the reinforcing engineer units theoretically are specially trained in one type of work. In actial operations, however, it appears that these units are ussed interchangeably; this indicates that the training is more general than would appear from the titles of the units. These engineer units are quite dissimilar in organization from the divisional regiment and are not as readily adapted to the reinforcement of that unit as are the corps and army engineers in the U.S. Army. The lack of a definite system for the command of reinforcing engineers by the division engineer also makes for a lessened efficiency in their operations. The small staff of the unit engineer also prevents second planning in the necessary detail for the work to be done by the attached engineers.
1. NIGHT ATTACKS.
a, General.
The Japanese are of the opinion that they have great ability in the conduct of attack during hours of darkness. Night fighting tends to compensate, in some measure, for the inherent wealness of Japanese artillery and the absence of cooperation in the use of the combined arms, a tactical deficiency which has characterized their activities thus far. In addition to this, the night attack favors the tactics of the close assault, usinf the bayonet and grenade which always has been emphasized in Japanese basic infantry training. Night attacks generally are made on a narrow front and wth limited objectives by reason of the difficulties of control, direction, identification, liaison, flank protection, and artillery support. At times, it is possible to leapfrog units past others to go on to deeper objectives when roads are available for the attempt, and hours of darkness still remain. Often, night attaks are made with the purpose of inflicting damage on the rear installations of the allied forces, with the Japanese troops being withdrawn before daylight. Ruses and stratagems are employed in a variey of ways to casuse confusion and a disclosure of the positions.
b. Purpose of night attack.
Japanese doctrine and practice indicate that units of all sizes, including divisions, may engage in night attacks for the following purposes:
(1) To exploit success gained during the day.
(2) To secure limited objectives whose seizure will facilitate an attack to be launched the following day.
(3) To conceal Japanese large scale activity elsewhere, such as a whithdrawl.
(4) To prevent or harass a withdrawl or to complete the defeat of an already disorganized opponents before he can be reinforced.
(5) Where Allied fire power has been superior that it was impossible to advance during daylight.
(6) Small scale night attacks have been used merely for harassing purposes and to inflict as much damage to material and supplies as is possible.
c. Time of attack.
According to Japanese field service regulations, the period just after dark and just before daylight are the ideal hours to launcg the attack. In practice, however, The Japanese have commanded night operations at all hours during the nihgt. Generally, an attempt is made to reach the objective shortly before dawn in order to allow a coordinated renewal of the attack from the new line of departure at daylight.
d. Reconnaissance.
In the preparation for the night attack, special emphasis is placed on gaining a thorough knowledge of the terrain and of the disposition of the hostile forces. Reconnaissence patrols are employed and forward observation posts established . The approach route is marked out and generally follows continuous terrain features in the desired direction. If sufficient time is available for the preparatory phases of the attack, the reconnaissance will be quite thorough and detailed. If complete surprise is desired, the Japanese commander will often forego a throrough reconnaissance substituting instead a cursory examination of the terrain.
e. Objectives.
In theory, the objectives of a night attack are limited, and are shallow in comparison to those of attack in daylight. Terrain features are generally chosen in order to overcome difficulty in keeping direction during the advance. In the actual attack, the Japanese often assign terrain features which are not clearly perceptible as objectives. In addition, objectives are often beyond the capabilities of he attacking troops. The final objective is usually the rear edge of a defended position about 1,000 yards deep. About one half of this distance is covered om the first advance and is termed the first objective.
This depth of objective necessitates night passage of the defenders lines during the first advance. Infiltration units are usually employed prior to the attack to harass and disorganize defenses, and often to be conceal the direction of the main effort.
f. Conduct of the attack.
The infantry generally is organized into two assault teams supported by a reserve. If the objective is very limited, one team will be used. In the normal situations, however, a wave of assaulting troops goes forward and seizes the line constituting the first objective, whereupon the second wave passes through the first and moves on to the second objective. This second wave also is assigned the mission of repulsing counterattacks. The relative strength of the first and second waves depends on teh strength of the defenses at the first and second objective. A battalion generally attacks on a 450 - 550 front, with two rifle companies in the first wave, and two rifle companies (less troops assigned to the reserve) in the second echelon. Where the objective is more than 1,000 yards distant, two battalions may attack in column, with the rear battalion charged with securing the second objective. The infantry troops assault with great reliance on the bayonet. Battalion guns are used to reduce obstacles, and machine guns participate in protective fire, especially on the flanks. Engineers are sent out in advance to cut wire and destroy obstacles; they are allowed about 1 to 3 huors to accomplish this mission.
Decontamination units will be employed where gassed areas are liable to be encountered. Smoke laying units may be used if there is danger of illumination by defense searchlights. If the night attacck is to be a complete surprise, the Japanese will dispense with an artillery preparation. The attack on the first objective is generally one of surprise. When the Japanese precede the assault with artillery fire, the operation is said to be an attack in force. The movement on the second subjective is generally such an attack, and artillery then is used in close support of the infantry. A battalion of artillery is usually in support of an infantry regiment. The artillery commander prepares fires which will be available on call during the attack. Rockets and other pyrotechnics are used for signaling purposes between the infantry and artillery. In the preparation of the artillery plan, special attention is given to the possibility of counterattacks.
2. RIVER CROSSINGS.
a. General. In theory, Japanese river crossing methods are essentially the same as those employed by other modern armies. Surprise is always sought where the crossing is to be made under assault conditions, with feints and diversionary advances designed to conceal the location of the main crossing.
Figure 6. Typical organization of a river crossing. |
Normal attachments to a division about to cross a river will include antiaircraft units, engineers, artillery, observation
aviation, and armored vehicles. The advance to the site of the crossing is made on a fairly wide front and is preceded by
advance detachments which attempt to drive back enemy patrols, to seize existing bridges, and to procure material and
boatsfor bridge construction purposes.
The engineers conduct thorough reconnaissance for possible ferry or bridge sites and to aid in the procuring of bridging material. b. Operations in Burma. In Burma, river crossing operations have played an important part in the Japanese campaign. The engineers generally provide the means for initial river crossings, using boats, rafts, ponton equipment, and at times, rubber craft. Primarily, however, the Japanese have shown great ability to improvise and adopt expedients. Local natural material such as bamboo, standing timber, and vines are among the many materials used. The Japanese have shown much skill in the construction of rafts and ferries. These are usually made of bamboo, or by making improvements on such native or local craft which may be found in the river areas adjacent to the site of the crossing. During the Manipur campaign, in Burma, the majority of all supplies and troops sent across the Chindwin River were transported in ferries and rafts of Japanese constrution. c. Defense of river lines. In their defense of river lines, the Japanese have adopted the conventional method of defending from the friendly shore. But in recent operations, they frequently have set up a perimeter defense on the hostile shore in order to prevent a crossing of the river. Once the perimeter has been pierced, howecer, the Japanese often will effect a complete withdrawl and abandon further attempts to defend the area. The Japanese reaction to a recent crossing of the Irrawaddy river in Burma by Allied troops is interesting. The initial crossing was unopposed, and, since the defending Japanese division defended along a front of approximately 50 miles, 3 days from the time of the crossing elapsed before a force of any appreciable size could attack the Allied bridgehead. During this period, the Japanese employed harassing and infiltration tactics. Reserves were committed, in a piecemeal fashion, in a series of counterattacks. The Japanese again proved themselves capable of concealing their movements by exploiting the cover of |
Medium guns were sited singly in echelon along the line of fire and, to protect them from counterbattery fire, they were located at their upper limits of range.
3. COMBAT IN WOODS AND INHABITED AREAS.
a. Woods.
(1) The offense.
During offensive operations, the force charged with the capture fo forested areas must be kept as small as possible. The offense is launched in coordination with operations taking place outside the woods. The Japanese concede that coordination is quite difficult in such terrain and, in consequence, grant considerable independence of action to the units directly charged with the offense. Artillery and engineers are often assigned to render direct and close support. At the outset of the operation, an attempt is made to envelop the defending force by moving around the woods, while at the same time a frontal advance through the forest is ordered.
Flank defenses on the inside edge of the woods are neutralized, the troops reorganize, and then continue over existing trails and paths. During the advance, precautions are taken to insure that the main body is not decoyed into an ambush.
These precautions take the form of small patrols which reconnoiter in front of, on the flank of, and behind the main body. Since artillery support often may be impossible, the advancing infantry is charged with clearing such obstacles and barriers as may be encountered. Wehre there is a wide expanse of wooded areas, successive objectives are assigned, and these are seized as the advance continues. When the passage through the forest has been complete, the Japanese organize with a view to resting possible counterattacks.
(2) The defense.
When woods are used by the Japanese on the defensive, they establish the main line of resistance behind the edge of the area so that the trees will not interfere with supporting artillery fire. IN very dense areas, the main line of resistance will be the front edge of the forest, with the wooded zone being used to conceal units in the rear or in reverse. Japanese regulations admit, however, that there are times when the main line of resistance might be located within the wooded areas. In the organization of the ground for defense, the Japanese will utilize clearings, trails, and paths by constructing obstacles, barriers, and other fortifications to hamper the advance or to lead the attacking troops to unfavorable terrain, thus facilitating a Japanese counterattack.
Counterattacks are generally launches as soon as possible in order to take advantage of the natural confusion which follows when troops pass through densly forested localities.
b. Inhabited areas.
(1) the offense.
While an attack on an inhabited area gemerally is conducted along the lines of combat in woods and forests, a greater use of artillery is made in urban warfare. Heavy guns are used to destroy fortified areas. Normal demolition work is assigned to engineer units. Flank defenses are neutralized, and the adb=vance through the inhabited area continues.
Where centers of resistance are encountered, such as isolated troops defending from cellars and other improvised strongpoints, the Japanese assign small group units which are left behind to destroy such small pockets of resistance. Tanks, flame throwers, grenades, and demolitions are sone of the weapons and methods used to accomplish this mission. As in the case om large wooded areas, succcessive objectives will be established if the city or inhabited locality is large. If the attack is to be at night, the element of surprise must be maintained. As the defensive positions on the outskirts of the city are attacked, small units attempt to capture key defense points on the inside endeavoring to create confusion and to effect a complete disorganization of the defensive system.
(2) The defense.
The Japanese maintain that the principles for the defense of inhabited areas are similar to those which govern the defense in forested areas. When defense sectors are assigned, independence of action is given each sector commander so that, if enemy archieves a penetration in one area, other sectors will not be affected. Artillery is sited so that mutually supporting flanking and oblique fire can be delivered.
Buildings are used in the organization of strong points, and preparations are made for the rapid transference of supplies to positions where they may be needed. Communication measures are adopted, with positions being improved upon continuosly.
In one town in Burma, all permanent buildings which had not been destroyed by artillery fire were mined. These mines consisted of bombs which were set to explode through the use of electrical detonators. Concealed wiring led to a central point. The Japanese apparently intended to blow up the town after Allied troops had entered and occupied it.
In the defense of a town in the Philippines, the Japanese made an extensive use of revetted positions for tanks. Tanks were emplaced so that only the gun could be seen, and positions were sited along all logical avenues of approach. Tank emplacements were covered by fire from rifle and machine gun pits. The Japanese held defensive fire to ranges of 50 to 100 yards and then only fireds at remunerative targets. Tank led counter atttacks were frequent. A mobile reserve was employed which moved at night according to indications of an impending attack and withdrew to protected positions during artillery fire. Infiltration tactics were employed by small suicide units using lunge and magnetic mines. The Japanese made full use of night in order to rearrange troop dispositions and defenses; during the daylight no movement was made within the defended area.
4. DIVERSIONARY AND SUICIDE OPERATIONS.
a. General.
Infiltration and raiding tactics, by land and water, have received increased emphasis in recent operations. Such tactics exemplify the tendency of the Japanese to welcome and opportunity to embark on missions tantamount to suicide and beyond the capabilities of the troops of oher armies. Close quarter tank hunting parties,
Figure 7. Typical Japanese defense of a small town. |
counterbattery raiding detachments,
special amphibious assault units, amphibious combat platoons, and various modifications of these have been used at many
places.
b. Raiding and infiltration tactics. (1) Harassing raids. Operations indicate a persistent use of specially equipped infiltration and raiding parties. The Japanese direct that the mission of these units is to attack and harass enemy beachheads, rear installations, and other vittal targets in order to facilitate the counterattack of the main Japanese forces. Primary objectives include command posts, communication facilities, artillery and mortar positions, closely grouped units, and rear area installations in that order. A high standard of qualification is set for personnel of the raiding units. Intelligent individuals in excellent physical condition, with ability to appreciate terrain, and capable of withstanding hardships and dangers confronted in operations of this nature are desired. Men are expected to and do act in the capacity of human torpedoes, if necessary, in order to assure successful completion of an assigned mission. The unit is trained in all elements of offensive fighting - signaling, use of demolitions, cover and concealment, and ground reconnaissance. Surprise is constantly sought, and the leaders of these units are charged with responsibility for training in and employment of ruses and stratagems. Small raiding units generally consist of an officer and four to ten men, organized into small teams. A column formation usually is empolyed in the advance, with the officer in the lead, but this formation may be modified as the situation and terrain dictate. When several objectives are located in the same vicinity, a number of similkar raiding units may be employed in a coordinated attack. The entire operation will be commanded by one officer, and a simultaneous attack will be launched on his signal. The plan for each operation includes a reorganization after the attack has been executed. |
(2) Materiel and destruction raids.
In addition to the employment of raiding parties on missions of a harassing nature, the Japanese have made considerable use of materiel raiding parties. These units infiltrate into and behind the Allied lines, endeavoring to destroy items of equipment and armament. Primary targets of these units are artillery and vehicles; other destruction includes communication facilities and aurcraft. The raiding units are most active during Japanese attacks, since they attempt to destroy that equipment which will have an important bearing on the course of the campaign.
Target objectives are chosen carefully, and a thorough reconnaissance is made prior to the operation. The raiding parties are composed primarily of infantry, with such additional troops, generally engineers, as may be required.
c. Diversionary units.
(1) Attack in force.
Japanese Army elements, known as "Diversionary units", are organized for deep penetration into hostile territory and execution of surpeise attacks on vital enemy military installations. Generally organized in company strength, they usually are specially equipped and may move to the area of operations by submarine, bt air, or by small group infiltration through the forward positions of hostile troops.
These units often operate along supply routes and attempt to attack supply or troop convoys by using the tactics of surprise or ambush. Information concerning the terrain and the most widely traveled routes of supply, rest and bivouac areas, extent of march security measures, and the type of motor transport used by the enemy is gathered. The area selected for the attack is generally that which offers a minimum of cover and concealment to the convoy but which permits an effective ambush. Road blocks and land mines are prepared to immobilize the convoy at the time of the attack.
The convoy is allowed to pass through the advance guard of the diversionary unit unmolested, and at the most opportune moment the attack is commenced. Upon completion of the mission the troops withdraw to a predetermined assembly point.
(2) Guerrilla units in diversionary operations.
In the numerous by-passed areas the Japanese have employed guerrilla type diversionary units. Missions assigned to these units are such as will allow wide scope in the exercise of initiative. The unit operates on the principle that while it destroys the enemy it must preserve itself. Cooperation with air and naval headquarters is arranges in order to transport the unit to its destination and for the purposes of supply and communication.
The duration and raiding distance of each action will vary, depending on the terrain and the opposition encountered. The Japanese believe that a large mobile unit can operate for about 20 days and travel 150 miles. If supplies can be dropped by plane, the period of operations can be extended to 2 months. These units also operate against rear areas of the opposing troops and try to avoid contact, operating with secrecy from an established base behind the lines of the opponent. Great styress is placed on the use of explosives and demolitions in order to block supply routes and disorganize rear area troops.
(3) Suicide tactics.
The use of units and personnel to accomplish hazardous missions by suicide tactics is definite organic part of the overall Japanese tactical program. Suicide assault units generally are composed of two or three men. Officers formerly commanded such units, but heavy losses of key military personnel have caused the Japanese to use a leading ro superior private as leader of the detachment. since a thorough knowledge of the terrain and enemy situation is necessary, the Japanese use seasoned personnel for these operations. The suicide units, depending on the mission, establish advanced key points, move around the enemy position, and launch their attack from the rear.
Japanese suicide tank hunters have been employed on numerous occassions. Armed with various types of explosives, the suicide soldier endeavors to destroy a tank by thrusting an armor piercing charge on the end of a pole against the tank side armor, by hooking explosives on tank guns, and by other close assault methods which, if successful, usually result in the death of the individual attacking the tank. In still another method, the Japanese soldier remains concealed in a narrow trench with an armed and fuzed aircraft bomb. As the tank passes over his position, the soldier strikes the fuze, detonating the bomb.
Another development in the suicidal trends of Japanese Army tactical doctrine is the use of the one-man, depth charge boat. The latest weapon is made of plywood and is capable of traveling 18 knots. The boat is headed for a transport at full speed; when in position to strike the hull in the vicinity of the engine room, it makes a U-turn and drops its depth charges. There is a 4-second time allowance between the release of the charge and the explosion. In order to be effective, the depth charge is released about 5 yards from the ship attacked. In most cases, the pilot of the craft is killed by the explosion.
5. COMBAT IN EXTREME COLD.
Japanese discussions of combat in extreme cold and snow are concerned primarily with the care and protection of the individual soldier and his equipment. They appear to intend to apply their normal tactics of offense and defense to winter warfare, with only a few modifications considered worthy of presentation in detail. However, they have had considerable experience in combat and maneuver in the interior of Manchuria and North China. The troops assigned to these areas should be well adapted to combat under such extreme conditions as prevail there for several months of the year. The main points stressed in their doctrine are mentioned here.
Operations are to be conducted so that they may be brought to a successful conclusion as soon as possible. Cavalry and ski troops are to be the main reconnaissance elements. The infantry is to maintain the advance and avoid any permanency of position. Assault distances are shortened , since the wearing of heavy clothing precludes long marches and maneuvers. Tanks and other equipment are camouflaged so that they blend with the snow and the terrain. When horse cavalry is present, the charge is to be the favorite type of tactics employed. Artillery weapons are concentrated and observation posts established to prevent surprise by enemy movements through mist and fog frequently encountered in colder climates. Movement of artillery and heavier equipment is confined to cleared areas and roads, and the troops try to avoid deep snow and other impassable areas.
Engineer units are charged with the preparation of traffic facilities. Other engineer duties include removal of obstacles, construction of emplacements and fortifications, procurement of material for construction purposes, and possibly the establishment of a water supply.
b. Attack.
The Japanese advance in several columns prior to the attack, but they realize the danger of splitting up an attacking force, particularly in compartmentel terrain, into too many smaller units. Each unit column is directed to concentrate on attacking the enemy to its front. Only if this attack is successful is it to continue against the flanks and rear of the hostile forces. Japanese regulations direct that wide turning movements should be employed wherever possible; this maneuver follows, and is accompanied by, a frontal attack to contain the defending troops. The use of cavalry to assist in the main operation is included, in the execution of the attack, Japanese troops shuold utilize terrain features such as roads, valleys, crest lines. Maximum use of defiladed areas will be made to increase the element of surpriseand to protect the advancing troops.
Artillery is sited so as to deliver flanking fire, and during the initial bombardment the infantry will advance its line of departure as close to the defending troops as possible. Heavy weapons will be emplaced on commanding ground to the rear of the advancing troops in order to support assault troops engaged in climbing a slope or occupying a summit. Vigorous pursuing fire will be inflicted on the defending troops at the moment of their expulsion from a summit, since the Japanese maintain that a maximum of damage can be inflicted at such a time. Where the main line of resistance is on the rear of a slope, and the Japanese are successful in reaching the crest, their doctrine calls for an immediate forward movement of artillery and heavy weapons both to complete preparations for defense against possible counterattack and to continue the advance.
When battle is imminent, each advancing column in the Japanese division makes its own general estimate of the situation and endeavors to act in such a manner as will facilitate movement of the other columns. Cavlry reconnaissance units and aviation will continue reconnaissance, rendering reports to all units concerned. Any available mounted troops will be used in harassing mission in order to effect the most favorable conditions possible for the advancing Japanese. Depending upon the situation, pursuit will be conducted either by maintaining close contact or by striking along the enemy route of withdrawl.
c. The defense.
When they are on the defensive in mountainous areas, the Japanese believe in maintaining as large and conveniently located reserve as the communication and transportation means will permit. Approaches to their defensive positions are generally fortified, and continuous observation is maintained to prevent surprise attack. These security measures are not neglected even in areas where the terrain would make enemy movement difficult. Elements of the reserves are kept in readiness to strike against the flanks and rear of the attacking troops. When the enemy attempts a turning movement, the Japanese cavalry tries to secure the flanks and rear of the defending troops against such enveloping maneuvers. Aviation is employed to obtain quick warning of such projected operations.
Occupation of summits, saddles, and high ground is considered of prime necessity in order to deliver artillery fire on slopes and valleys. artillery is often emplaced so as to neutralize the forward slopes of hills in fron of and the road to the rear of the enemy. At times, a portion of the defending force occupies a valley bottom in order to fire at slopes and valleys held by the enemy. Once the enemy launches an attack, fire is intensified, and a counterattack is made, preferably at the point where the attacker reached the heights and before he has had sufficient time to reorganize his forces. Japanese troops, occupying sectors not subject to attack, or in sectors from which an attack has been repulsed, attack the flanks and rear of the enemy who are attacking in adjacent areas. However, defensive positions are not completely abandoned in such cases; instead, key points are manned while the assistance to adjacent units is being rendered.
6. MOUNTAIN WARFARE.
a. General.
The Japanese doctrine for mountain warfare as given in their field service regulations is quite general. No clear distinction is made between operationsup corridors and those against transverse ridges. No discussion is givem of the relative advantages and disadvantages of assault along natural avenues of approach as opposed to attack along ridge lines and side hill slopes running generally in the direction of attack. While the value of observation is stressed, no emphasis is given to the necessity for taking or neutralizing enemy points of observation as primary objectives of any mountain operation.
The vulnerability of mountain operations, especially supply lines, to aerial attack is neglected, as is the possible role of airborne units in blocking lines of communication. The role of antiaircraft artillery in the protection of movement in rugged country is not taken up. The high points of their doctrine are discussed in the following paragraph.
The Japanese understand that rugged terrain features make it difficult to control large units in mountain warfare; for this reason, they grant each unit operating in such country a certain independence of action. Occupation of commanding heights is a paramount objective, and opportunities for surprise attacks, which weather conditions make possible, are not overlooked. Existing road nets must be improved upon, and liaison between adjacent units is maintained by utilizing aviation and various types of signal communications. Approaches to the high ground are covered by artillery fire, and a constant observation of the enemy's movements is maintained.
7. AIRBORNE OPERATIONS.
a. General.
The Japanese employed parachute troops, to a limited degree, during the initial stages of the current war, but afterwards these were relegated to the background as fas as operational use was concerned. They reappeared during the campaigns on Leyte Island, however, and this, coupled with continued training and teh possible organization of complete airborbe divisions, should indicate that the Japanese have not discarded their plans for the future use of parachute and airborne troops.
b. Tactical employment.
(1) Prevention of withdrawal
Duirng June, 1942, Japanese paratroopers were dropped behind the British troops who were attempting a withdrawl. The purpose of the maneuver was to delay the retreat until Japanese ground troops could come up. The operation occurred at Koepang, Timor island, and was successful. Twenty to 25 transport planes were used on 2 successive days. The drop was made on a comparatively level area a little more than 1 mile from the nearest Allied forces. Each transport carried 15-24 partachutists, and these were dropped in groups of six to eight.
(2) Seizure of vital installations.
At Palembang, Sumatra, in February, 1942, Japanese parachutists were assigned the task of seizing an airfield and large oil refineries before these installations could be destroyed by the defenders. The paratroops did obtain control of the field, but underestimated the strength of the defending forces who were able to demolish the oil refineries. In this particular vertical envelopment, the descent was preceded by an attack by fighters and bombers. The parachutists arrived over the area about 10 minutes later. Flown in transport planes in two formations, each group consisted of nine planes. The drop was made from a fairly low altitude.
(3) Diversionary operations.
Anoher paratroop operation occurred on Leyte Island, in December 1944. The apparent object of the attack was to destroy American aircraft on the ground thus permitting a Japanese convoy, then enroute, to anchor and discharge reinforcements without interference. The plan was the most ambitious undertaken thus far. The landing was preceded by bombing of the drop area, with cover provided by fighter aircraft, and a smoke screen was laid to aid the parachutists. More than 75 planes were used in the operation, and approximately 250 - 300 paratroopers reached the ground. After landing, the troops showed evidence of having been poorly organized for the mission, and damage done to American installations was in no way commesurate with the Japanese losses of aircraft and personnel.
(4) General summary of paratroop tactics.
Prior to the approach of the airborne troops, the Japanese attack with fighters and bombers in an endeavor to achieve local air superiority and to neutralize ground installations which might jeopardize the landing. smoke may be used to achieve additional surpeise and to conceal the landing. To exploit surprise, the first drop will be from altitudes of 300 to 400 feet. Reinforcement is made by maintaining reserve at base airfields and committing them as the occasion arises. Landings are generally made in the morning hours, but instances have occurred where the Japanese have waited until nightfall to launch their attack. The Japanese probably have learned the importance of supporting arms for paratroopers. The operation on Leyte indicated that troops of other branches of the army were used in addition to regularly assigned parachute and airborne troops.
8. CHEMICAL WARFARE.
a. General.
In common with other armies, the Japanese have trained and equipped troops for chemical warfare. Their tactics and weapons are conventional so far as can be judged from their doctrine. Their basic tactics involve the projection of gas clouds and sprays and the placing of contaminated terrain barriers in manner which will insure that the maximum benefit will obtain to the other arms from the efforts of the chemical warfare troops.
b. Weapons for tactical employment.
(1) Artillery.
In general, the tasks that require long or medium range and accuracy are assigned to artillery, rather than attacks on hostile forward positions, although artillery occasionally may be used for such attacks. The major tasks of gas fire by artillery are:
- To neutralize enemy artillery observationposts and gun positions
- To harass enemy rear areas.
- To interdict key traffic points.
For accomplishment of these tasks various types of fire are advocated. These are:
(a) Neutralization fire.
The purpose of this is to take advantage of minor objectives such as artillery positions, observation posts, machine gun positions, and skirmisher trenches or intersections of communication trenches. Thorough preparation is required and attained by employing all available methods of observation so that fire may be highly concentrated and ordinarily completed within 1 minute.
(b) Harassing fire.
This aims to cover the target area with gas clouds, compelling opposing troops top wear their gas masks for several hours, and so gindering theit maneuverability. Major targets are moderate concentrations of troops and bivouac areas. Minor targets are military positions, observation posts, vital points of communication and skirmisher trenches, and passages through deep ravines and forests. Fire begins with a surprise concentration using approximately half the number of shells allotted, followrd by a slower rate of fire with the balance of the shells.
(c) Contamination fire.
The purpose of contamination fire is to compel opposing troops to retrear from their positions, to make it impossible for them to utilize a key position for any length of time, and to disrupt communications. Targets are any areas which it is desirable to contaminate such as forests, bridges, entrances to villages, road intersections. and narrow paths. A persistent agent, presumably mustard or a mixture of mustard and Lewsite, would be used. The shells must be dropped to cover the area uniformly. Fire should be continued to maintain a gas concentration.
(2) Mortars and projectors.
The tasks of mortar and projector units are to neutralize or harass the enemy . A mortar gas cloud is placed on enemy troops, or persistent gas is fired to contaminate personnel and terrain.
A Japanese manual on the use of gas states that gas shell is to be used by a trench mortar company of 12 mortars to support attack echelon troops. The effect must be concentrated to secure surprise. Three types of attack gas shell are mentioned:
(a) For annihilation.
The aim is to destroy enemy fighting ability completely. The Japanese presume gas masks of their enemy to be either poor or non existent. For an area of 3,227 square yards, about 400 shells are required.
(b) For partial annihilation.
This tactis proproses to produce partial destruction of the fighting ability of enemy forces and to give the Japanese "extensive control" of the front. A total of 200 shells for 3,227 square yards is required.
(c) For harassment.
Hindrance of enemy activities is sought by this means. Some 80 shells are required for an area of 3,227 aquare yards.
Good effects can be achieved with gas shells only where they are used profusely. Therefore it is important that the mortar units are not split up. The mortar company should use all of its 12 mortars, and the battalion should be used in a unified action. Even two battalions may be used for a single important objective. Coincident with the usual Japanese tendency toward flanking attacks, it is stated that trench mortar units may be assigned to a detachment on a flanking mission.
The manual on mortar fire makes no specific reference to a chemical agent beyond speaking of "special smoke". The Japanese 90-mm mortar gas shells, both true gas and gas HE types, are normally supplied with vomiting smoke fillings. Inaddition, there are shells with a choking gas filling.
The Japanese say that daybreak is the best time to use gas, but twighlight is also effective, Wind in the direction of enemy troops is preferable, but too much stress is not to be laid on this. Wind velocity should be under 11 miles per hour, the Japanese believe.
When coordinating with infantry, shells are aimed by the Japanese about 218 yards from the front line. This appears to mean a minimum distance, with a following wind, to prevent casualtied to their own forces from shell fragments, but it also may be designed to allpw gas trails to unite by the time they reach enemy positions and thus avoid ungassed gaps in the enemy line. When firing is completed the Japanese troops don their masks and advance.
One manual states that gas is generally used after HT fire attack has been in full development. The advantages of this are that HE forces enemy troops into trenches and fox holes, after which the gas acts as a screen for advancing Japanese troops.
(3) Toxic smoke candles.
The use of toxic smoke (vomiting gas) generated by candles is planned in connection with the use of screening smoke. Chemical warfare units and units of other branches of the army, particularly the infantry, are the users. Its purpose is to reduce enemy efficiency and give the attacking force sufficient predominance to gain its objective. The screening effects also conceal the directionof attack and reduce enemy fire power.
In laying a screen, candles are placed on a projecting shelf in the forward wall of a trench, or special smoke trenches are built. Candles are ignited at the same time in the various trenches on signal from the commanding officer. Each manof the gas squad ignites from 30 to 60 candles. The number of candles to be used on a given occassion varies with distance from enemy troops, width of cloud desired, tactical effect sought, depth of smoke cloud necessary, and weather conditions.
Screening smoke candles may be used prior to toxic candles to ascertain effets of currents and wind. They may be used also to increase the thickness of the screen when the volume of smoke supplied by the toxic candles diminishes too early. Troops advancing after the discharge of a toxic smoke cloud wear masks. The rate of their advance may be reduced to keep closely in the wake of the smoke cloud, but if necessary they are to advance before the smoke candles have finished emitting.
In addition to the ordinary vomiting gas smoke candles and tear gas candles, designed to be placed on the ground, The Japanese have candles which are self-projecting. These weapons, fired on the rocket principle, have a maximum range of about 300 yards. They easily could be used in a cross wind, or possibly even in a head wind.
(4) Aerial gas attacks.
Japanese bombers, fighters, and reconnaissance planes may be used to place gas, either by bombing or spraying. If these are used, low level attacks will be made, with evasive maneuvers, and a great volume of gas dropped in a short space of time on the objective in the hope of achieving surprise.
(5) Contaminated barriers.
The enemy described these as contaminated belts which will be placed in front and on flanks of a position. Installations and bridges are suggested targets. Contamination may be placed by artillery or mortar units firing persistent gas shells, by airplanes, or by use of gas mines. Such barriers would be particularly useful in retreat.
(a) Gas in defense.
Gas can be employed on a very large scale to accomplish a variety of missions in defensive fighting. Its use begins with aerial gas attack during the approach march of the attacking force. All kinds of gasses are used, but particularly persistent gas, in conjunction with HE shell.
The Japanese suggest the following missions of gas in defensive fighting;
- to delay the movement of the enemy's attacking column over a long period.
- To disrupt the enemy's assault by inflicting heavy lossws on his troops by gas attack.
- To demoralize the enemy by harassing his rear areas and supplies.
- To make possible quick maneuver of the defense and to strengthen weak points while taking advantage of delays forced on the enemy by gas as he prepares to assault.
- to force the enemy to change the direction of his main attack by placing large barriers of contamination in tacticaly important areas.
When an area is gassed, gas shells, toxic smoke, and aerial gas attacks are sometimes used jointly. The specific mission for wach weapon, will, of course, depend on its individual capabilities.
The Japanese describe their defensive gas tactics in terms of a complete action. They consider measures to be taken during the advance of the enemy, their deployment of forces, and the main engaement. Japanese measures to impede the advance include harassment and infliction of gas casualties so that the enemy cannot bring his full strength to bear.
(b) Gas in attack.
The principal difference between use of gas in attack and in defense as stated in Japanese doctrine is that non-persistent gases are the means used to assist the main attack directly. Persistent gas may be used on the flanks of the attacking force or on spots at the rear of the enemy lines which may easily be by-passed later or crossed withuot too mucj difficulty.
In direct support of an assault, the task is to conceal the attacker's intentions, movements, and especially the key points of attack. At the same time, the effectiveness of enemy fore power and his strength generally can be diminished. Screening smoke and toxic smoke, frequently mixed together, are used on a large scale; with candles producing the smoke. Non-persistent gas shells can also be fired by mortars and artillery.
It is necessary to get close to enemy positions before releasing smoke to insure its effectiveness. Time of firing the smoke is based on permitting completion 10 minutes before the hour set for the assault. Enemy troops are harassed and their combat strength is weakened by repeated attacks with non-persistent gas. In many cases, the Japanese undoubtedly would use relatively light concentrations of toxic smoke from candles . Harassing concentrations of non-persistent gas, however, would also be laid down by mortars when available. Attacking infantry cas use gas grenades, particularly against the enemy in tanks, pillboxes, or other shelter. Tank units protect themselves against enemy antitank guns by firing smoke from short range smoke projectors to reduce visibility.
To interfere with enemy maneuver and protect flanks, the Japanese advocate the use of persistent gas in the follwing missions:
- To restrain ebeny maneuver, persistent gas can act to restrain the movements and check the advance of reinforcements for the enemy. Route in the rear of enemy positions are covered with a belt of persistent contaminating gas. The gas can be fired by artillery or placed by fast armored spray cars, although none of the latter has been identified thus far.
- To provide flank protection for attacking units persistent gas is used o scatter the enemy on the flanks, both forward and rear echelons. The gas can be placed by mortars or armored spray vehicles.
- To prevent enemy disengagement gas is used to make the enemy's escape from the combat area difficult. Lines of obstacles in the enemy's rear are contaminated. Thi is accomplished by contaminating bridges or fords of rivers, entrances of path or roads through forests, etc. However, a tactical sketch in the Japanese manual indicates the placing of non-persistent gas on enemy troops making use of such avenues of escape. This would seem a more logical procedure, as the attackers themselves would want to use the same advantageous terrain in pursuing the defenders.
c. Comments.
While the evidence is not conclusive, the emphasis placed by the Japanese on the use of toxic smoke (vomiting gas) candles leads to the belief that, under jungle conditions, they would rely more on these easily portable weapons than on artillery or even mortars. Their tactical doctrine also includes the use of ground contaminating agents, such as mustard gas, dispersed by chemical land mines, portable sprayers, and aerial bombs.
For warfare in more open terrain, the Japanese probably would make use of all their gas weapnos, with stress on their artillery, but more particularly special mortar battalions, motorized spray vehicles, and gas bombs and spray from planes.