The first tanks used by the Japanese army were of European manufacture. British and French designs were adopted and vehicles produced by Vickers, Carden-Lloyd, and Rennault were used on a small scale by the Japanese armed forces until domestic manufacture of armored vehicles was begun in 1929. Since the conclusion of the Tripartite Pact (27 September 1940), German tank designs apparently have been made available to the Japanese; and since the Nomonhan incident of 1939 on the Mongolia-Manchuria border, Soviet equipment likewise has been available for study by Japanese designers. Combat with the forces of the United Nations has afforded another source for ideas relative to the design of Japanese tanks. There is no evidence, however, that foreign principles of tank construction have exercised a direct influence on Japanese design.

Japanese tanks encountered thus far have been inferior to those utilized by Axis and Allied armies in Europe and North Africa. Their armor was too thin, although of good quality, and insufficient attention had been given to the utilization of deflection angles. In many cases reentrant angles had been formed, and no effort apparently had been made to protect turret rings or mantlets against jamming or splash.

No tanks encountered, with the exception of a negligible number of heavy vehicles, have been armed with weapons heavier than 57-mm guns. Light tanks have 37-mm guns, and one variation of the Model 95 (1935) light tank was armed with a 47-mm gun. Machine guns are mounted both in front and rear, but it is doubtful if the rear weapon can be fought at the same time as the other armament. All guns, with the exception of the 47-mm gun and the new Model 1 (1941) 37-mm tank gun, are low-velocity weapons. It should be borne in mind, on the other hand, that the development of hollow-charge ammunition to some degree will compensate for this disadvantage.

Crew space is cramped in models captured to date, and no escape doors or hatches have been provided. Visibility has been poor. Radio equipment has been installed on an extremely meager basis judged by the standards of the armored forces of other armies.

Improved Models Expected

Despite these deficiencies of earlier models, the design of efficient modern tanks, even heavy types, is not beyond the capabilities of the Japanese. They are familiar with the details of modern German models and have had an opportunity to observe American and British equipment. Limitations on the productive capacity of Japanese industry impose the necessity of freezing tank models in order to attain a reasonably large volume of production. Nevertheless, it would be unwise to assume that the Japanese do not or will not have more effective armored vehicles than those encountered to date.

Much heavier armor, or the addition of spaced armor to the present armor, can be expected in newer models. To compare with European and American standards, the armor of light tanks should be as much as 40-mm thick; that of medium tanks, 75-mm. Heavy tanks would be expected to have armor up to 100-mm in thickness. Heavier armor in each case would be compensated for normally by the installation of wider tracks to reduce ground pressure.

Equipment of medium tanks with a modern, high-velocity gun of at least 75-mm caliber would be imperative in any program of improving Japanese tank design, and the installation of coaxially mounted machine guns likewise can be anticipated. Hulls may be improved by a better employment of deflection angles, and accessory equipment will be augmented, particularly by the installation of two-way radios, perhaps in every tank. Greater attention will be paid to crew comfort. Escape doors, periscopes, improved vision, gas-fume extraction equipment, better antiaircraft armament, and similar accessories probably will be incorporated in modernized models. Continuance of high power-weight ratios may be expected, making possible high speed and good cross-country mobility.

Japanese tanks are classified into four types according to their weight. These are tankettes which weigh less than 5 1/2 tons; light tanks weighing from 5 1/2 to 11 tons; medium tanks with a weight range from 11 to 22 tons; and heavy tanks over 22 tons.