Chapter VII: Tactics of the Japanese Army

Part II: Application of Tactics

Section VII: Antitank Defense

1. GENERAL. a. Background. (1) The antitank methods adopted by the Japanese Army in antitank measures follow normal modern practice, except that the army as a whole is weak in antitank weapons. More thought, however, is given to the simpler forms of antitank defense, such as the use of antitank mines, incendiary grenades, gas grenades, obstacles, and the employment of special infantry assault squads (tank fighters).

(2) Experience in fighting Russian tanks at Nomonhan, Manchuria, in 1939 gave the Japanese Army an initial warning that more definite provisions must be made in its tactical organization for handling enemy tanks. As a result of much consideration of this problem, which was stimulated by the successful use of tanks by the Germany Army in the early days of the present war, a definite plan for resisting tank attacks was adopted. There is every indication that the Japanese have been studying and applying modern principles of antitank defense with the same careful attention which they devote to other tactical problems.

b. Exploitation of tank disadvantages. The Japanese envisage the inherent disadvantages of tank operations to be as given below, and their antitank instruction stresses taking every advantage of these conditions.

(1) Natural and artificial obstacles.

(2) Long tank columns which are difficult to camouflage.

(3) Adverse weather conditions which may prevail.

(4) Unfavorable working conditions and difficult observation which lower efficiency of crews.

c. Tank-hunting. Since the Japanese Army teachings lay a pronounced emphasis on coming into close contact with enemy tanks, it is well to draw attention to the fact that tank-hunting tactics are likely to be employed to a greater extent by the Japanese than by other armies. The reason for this is three-fold: (1) it is another manifestation of the Japanese spirit of the bayonet—the hand-to-hand encounter, in which the individual is expected to triumph over material, even if armed only with grenades; (2) the Japanese appear to be short of modern anti-tank guns, and only by denying one front do they produce reasonably strong concentrations on another; and (3) most of the ground over which they have been fighting lends itself to a close assault.

2. ANTITANK WEAPONS AND ANTITANK UNITS. a. Weapons. The Japanese Army generally has disliked single-purpose weapons. However, this dislike was abandoned from necessity, and early steps were taken to produce a 20-mm automatic antitank rifle which has been found with units in the field. It is carried by 4 men in combat, and transported on a cart or packed on 1 horse if not carried by hand. While the 37-mm gun is still retained in service and is used as a dual-purpose weapon, the 20-mm automatic antitank rifle is believed to be primarily used for antitank purposes. Other field and antiaircraft artillery weapons are considered suitable for use against tanks. A modern 47-mm gun, equipped with a high speed mount, has recently made its appearance. This weapon should have an effective antitank performance, while its low silhouette will aid in its concealment.

b. Nondivisional units. Nondivisional antitank units did not exist in the Japanese Army before the Nomonhan incident, but as a result of experiences in fighting Russian tanks, these independent antitank units were formed for attachment to divisions when necessary.

3. PASSIVE DEFENSE MEASURES. Concealment, camouflage, obstacles, reconnaissance, and warning nets are considered essential.

4. ACTIVE MEASURES. These include—

a. Action by antitank guns, accompanying guns, and mortars.

b. Bullet splash from machine guns and rifles at a short range (at least one squad firing at each tank).

c. Mines.

d. Tank fighters. These comprise men with special training and equipment for direct assault on tanks.

e. Tanks.

5. ANTITANK TACTICS. a. Mines. A cheap method of passive defense against tanks is by the use of tank mines. In an exercise involving an infantry division, 12,000 mines were laid by all units of the division. Where enemy units are known to have tanks, the laying of tank mines is considered the most essential duty of the division engineer regiment. The mines are placed in a conventional manner covering the logical routes of tank approach. Bridges in defensive areas are habitually mined, and any bridge which has been in Japanese hands must be carefully examined for the presence of contact mines before a tank unit is allowed to cross. Tank barricades have all possible detours heavily mined, and it is common practice to lay a few mines under temporary barricades with the idea that if the enemy removes the barricade, he will not suspect that mines have been laid in the ground underneath.

b. Tactics. A Japanese military term applying to antitank defense is "dansei bogyo," which is translated as "an elastic defense" and is highly descriptive of their entire theory of antitank defense. Briefly, this method of combat does not provide for strong resistance to tank attacks along front lines. Not more than 20% of available heavy infantry weapons are employed against a tank attack from front-line positions. On the approach of a tank attack all units, with the exception of one squad per platoon, fall back to positions from 800 to 1500 yards in the rear. The squad from each front-line platoon left in position scatters widely and, under cover of smoke laid down by the use of the grenade discharger, attacks the tanks with incendiary grenades as they come through the smoke. It is contemplated that this initial stage of the fight will scatter the enemy tanks, reduce control, and cause some casualties. If the tanks overcome the resistance of the front-line detachments they come under fire from the main strength of all available weapons of the infantry. While this and the front-line combat have been going on, some of the division artillery moves forward to positions from which it can fire with direct laying. If the heavy weapons of the infantry are unable to stop the attack, the main infantry strength, using smoke and incendiary grenades, makes a direct attack, relying on the artillery to their immediate rear to handle any tanks that get through. The main feature of this defense, as stated by provisional regulations, is that once an attack is stopped the enemy is pinched off, and by the operation of scattered units can be destroyed with grenades or any available weapons; and the infantry, although scattered, still can offer successful opposition to enemy infantry attempting to exploit the advance of the tank units.

c. Estimate. While it may appear that the Japanese Army will offer but weak resistance against a tank attack because of the nonavailability of modern weapons in sufficient numbers, this assumption should not lead to the belief that strong and suicidal resistance by individuals will not be offered.

6. DETAILED METHODS OF ATTACKING A TANK. a. Choice of ground. When employing tank-fighters, it is desirable to choose ground where tanks must travel slowly and where the attack does not interfere with the action of antitank guns.

b. Special troops. Each rifle company (sometimes machine-gun and heavy-weapon companies organize similar detachments) trains certain individuals as tank-fighters, and these are specially equipped for such action. Each man is armed with antitank mines and smoke hand grenades.

c. Methods. Three ways of attacking tanks are:

(1) The tank-fighter crawls toward the tank under cover, until he is within the dead space of the tank weapons. Next, he throws the mine, attached to a long string, about 15 feet in front of the tank and, by means of the string, pulls it directly under the tank.

(2) Several pairs of tank fighters move forward under cover and place a number of mines in front of the tank in such a manner that the tank must drive over one of them.

(3) A number of mines are fastened, 1 foot apart, to a 150-foot line. Two men conceal themselves with this chain of mines and draw the mines across the path of the tank as it approaches.

The tank-fighter is also taught to attack the tank by jumping on top, usually from the rear, and damaging the guns or rotating mechanism of the turret with picks. The pistol may be used to fire on the crew through openings in the tank. Another method is to blind the tank crew by throwing a shelter-half over the turret, covering the slits with mud, or "smoking it out." Naturally, all these forms of assault are feasible only if the friendly infantry can neutralize the hostile infantry accompanying the tanks. Tanks have been delayed, and finally stopped, by driving 3-inch wooden poles or 1- to 1 1/2-inch rods between the spokes of its wheels. Magnetized armor-piercing mines are also used at times.

7. EMPLOYMENT OF ANTITANK WEAPONS. a. Allotment. In country that is suitable for the operation of tanks a company of Japanese infantry may be found to be supported by from 2 to 6 antitank guns (37-mm or 47-mm). The infantry regimental antitank guns either may be allotted to forward battalions or, on rare occasions, held in reserve under regimental control. The 20-mm antitank, automatic rifle is described by the Japanese Infantry as "delivering antitank fire at short range and engaging the enemy's foremost heavy weapons." If there is any danger of a night attack by tanks, the 20-mm weapon may be posted forward of the main line of resistance and supported by tank hunting detachments.

b. Siting. The bulk of the antitank guns allotted to a position are sited as far forward as possible. Great stress is laid on siting guns in concealed positions and camouflaging them. To quote from Japanese regulations, "positions are to be selected at well covered points near the front line." Experience has shown that once dug in, these weapons are difficult to locate. It is likely that an antitank gun will sometimes be sited in very thick cover, with a small fire-tunnel cut out to enable it to cover a trail or other likely area for tank approach. The Japanese have sited machine guns in this way, and the practice well may be applied to antitank guns. Guns also may be sited on steep ridges or rocky slopes, from which positions they can fire at hostile tanks while themselves remaining inaccessible. Alternative positions are prepared, the regulations stressing that "it is advisable to move the gun from place to place thus avoiding casualties from enemy fire." In action the fire unit is generally the individual gun (a section), and the gun commander chooses suitable targets and directs fire upon them. While most of the guns are sited in foremost defended localities, a few are held in the depth of the position with the apparent task of dealing with penetration of enemy tanks. In the event of such penetration, infantry regimental guns, as well as field artillery weapons, also will engage the hostile armored vehicles. The fire plan of the infantry weapons is coordinated with that of the antitank unit. Except for reserves—if any—all guns are sited to cover the most likely lines of approach of enemy tanks. They are also sited to cover obstacles. An infantry platoon often is disposed on the route of approach in advance of the main position, but within range of artillery support from it. This platoon may have an antitank gun attached to it.

8. EXAMPLES OF POSITIONS. a. Natural and artificial obstacles combined. The position illustrated in figure 96 was prepared by the Japanese near Akyab, Burma. It provides an interesting example of an all-round tank obstacle, partly natural and partly constructed. A ditch, approximately 14 feet wide and 7 feet deep was dug as shown. Dirt, thrown out on both sides formed a small parapet, while water filled the ditch. The trench system dug near the ditch included 7 covered positions, each measuring 45 by 30 feet.

Figure 96. Antitank defense position.

b. A plan for antitank defense. In figure 97 there is shown a Japanese plan for antitank defense of an area in Burma. The following troops and guns were allotted to the position:

Figure 97. Japanese Plan for Antitank Defense.

(1) Area No. 1 was to be garrisoned by 1 company of infantry, reinforced with half a company of heavy machine guns (4 guns), 2 antitank guns, and 4 infantry (mtn) guns (75-mm).

(2) Area No. 2 was allotted 1 infantry company with half a company of heavy machine guns (4 guns), 5 antitank guns and 4 infantry (mtn) guns (75-mm).

(3) Area No. 3 was assigned 1 company of infantry, and 2 Mountain (inf) guns (75-mm).

(4) Area No. 4 was defended by 1 company of infantry, one half of a heavy machine gun company (4 guns), 4 antitank guns and 2 Mountain (inf) guns (75-mm).

(5) Area No. 5 was allocated 1 platoon of infantry and 1 heavy machine gun platoon (2 guns).

(6) Area No. 6 was assigned 1 platoon of infantry and 4 antitank guns.

c. Obstacles. At Butaritari Island, Makin Atoll, the Japanese dug deep antitank ditches outside of their main defenses at the tank traps, with winding narrow roads leading into the outer edges. (Fig. 98.) The crossings were covered from antitank gun pits and machine gun nests. Palm logs served as a tank barricade near one tank trap. (Fig. 99.)

Figure 98. Antitank obstacle.

Figure 99. Antitank obstacle.

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