1. GENERAL

A study of information from reliable Japanese sources indicates that the enemy has made changes in his tactical organization and employment of tanks. He evidently has been experimenting with the idea of greatly increasing the concentration of armored strength in a given sector of combat.

One Japanese source illustrates the employment of three tank battalions with an infantry division in a theoretical attack against hostile positions on a front of 3,200 meters (approx. 3,500 yds.). The tanks (probably all light) are organized on a triangular basis: three platoons per company and three companies per battalion (see fig. 4). Apparently, under this new organization, three battalions would constitute a regiment, although the word "regiment" is not used by the Japanese. The plan of attack calls for employment of 135 tanks—45 per battalion, 15 per company, and 5 per platoon.

This organization, greatly increasing the number of tanks per unit, generally follows American and German principles, and indicates that the Japanese have been studying these principles. The previously accepted enemy organization for the light tank company included 10 tanks.

Figure 4. Japanese Employment of Three Tank Battalions.

The plan of attack with three battalions attached to an infantry division, as outlined in figure 4, calls for a closely coordinated tank-infantry attack, supported by artillery. This tie-up with infantry has been standard Japanese doctrine for several years. Although the Japanese are believed to have more than one armored division as such, it is apparent that most of their armor will continue to be used within, or attached to, infantry divisions or smaller units. On suitable terrain, this armor is likely to be employed: as a spearhead for infantry attacks, as an integral part of an infantry-tank combat team fighting almost side-by-side, as support for infantry, as an enveloping force, and as a raiding force.

2. USING THREE TANK BATTALIONS

Details of the Japanese method of employing three tank battalions with an infantry division are illustrated in figure 4, which is reproduced from a reliable enemy source. Theoretically, the division is attacking on a front of about 2,500 meters (approx. 2,700 yds.) against "well-established" hostile positions covering a front of about 3,500 yards. The tank attack is being made in three waves or echelons. Two of the infantry regiments and two of the tank battalions are moving into the attack, while the third infantry regiment and the third tank battalion are in division reserve.

The first tank echelon consists of two tank companies, one in front of each front-line infantry regiment, under the direct control of the regimental commander. The mission of this echelon is to "neutralize antitank guns and strong fire points (which appear to be composed of strong tanks) and thus establish a passage for the main attacking force"—the second echelon.

The second tank echelon, moving 400 to 500 yards behind the first, consists of four tank companies, two in each regimental sector. Each company moves a short distance in front of an infantry battalion, four of which are in the front line. The tank companies are attached to these battalions and are under the battalion command in each case. These tanks "lead and support the attacking infantry." Depending on the situation, the support battalion of each front-line regiment may be called upon to "leap-frog" through the front-line troops and take up the attack.

The third tank echelon, consisting of one battalion, is held in reserve "under the direct control of the division commander." These tanks, "in order to exploit a battle success or to strengthen the division's striking power, may be employed to reinforce any area requiring it, or may be attached to any infantry unit as reinforcements," the Japanese state.

Previously established Japanese doctrine called for the use of only one tank company (consisting of 10 tanks) to each infantry regiment for such tank-infantry roles as outlined above. Apparently this was not enough armor for the Japanese. In a booklet titled "An Example of a Tank-unit Attack Formation," the enemy commented as follows:

The Japanese set forth the following "views" regarding the neutralization of antitank guns prior to the actual assault by tanks and infantry:

3. USE OF TANKS ON TARAWA

U.S. observers report that the Japanese had six or seven light tanks (Model 2595) in the defensive setup on Tarawa Island. Only two of these engaged in a tank-to-tank battle with our forces. The others were knocked out by naval and other gunfire.

After U.S. forces had captured the airport, and after the latter had been bombed by the Japanese, an enemy tank came out of a revetment, apparently to determine what damage had been done by the bombing.

Flying the Rising Sun flag, the enemy tank approached two U.S. medium tanks, turned while several hundred yards away, turned around again, and fired two rounds while approaching our tanks. Having missed its target, the enemy tank then did an about face and fled.

In another engagement, an armor-piercing shell from a U.S. medium tank tore the turret off the top of a Japanese light tank and put it out of action.

Except while in low gear, the Model 2595 light tank is not well adapted for movement over rough terrain. In low gear, it can cross fairly high obstacles and climb steep slopes. It can operate in water up to 3 1/2 feet deep and travel up to 90 miles without refueling.

This tank is highly vulnerable to close-in attack by small weapons, such as sticky grenades and Molotov cocktails. It can be set afire easily. Therefore, incendiary weapons are particularly valuable for combatting it at close quarters. No weapon in the tank can be depressed lower than 20 degrees below the horizontal, thereby leaving a dead space extending 23 feet in all directions from the tank, as shown in figure 5. Shaded areas have .25-inch armor and are the most vulnerable spots to small-arms fire and incendiary grenades. A man within this distance of the tank is not only in a favorable position to use his weapons, but he is comparatively safe from any of the tank's weapons.

Figure 5. Dead Space around Japanese Model 2595 Light Tank.

In every strategic area of the island, the Japanese had built tank revetments, which were located so that tanks in them could fire at soldiers and boats crossing the reef or at other suitable targets (see fig. 6). Most of the revetments were mutually supporting with other defense weapons. The revetments were located singly, indicating that the tanks were to be operated individually in defense of the island.

Figure 6. Japanese Tank Revetment (Tarawa).

The revetments sloped into the ground. The coconut-log sides extended about 4 feet above ground level. The tanks were driven forward into the revetments, permitting the 37-mm guns to fire to the front. To get into action, the tanks had to back out of the revetments and then turn around.