Active formation of tank units started alongside of combat. The first regulations and field manual were formed in 1931, due to the formation of the Kwantung Army and beginning of exercises. The Gunchzin tank brigade was the main experimental tank unit of the time, dictating tactical and technical requirements.
In the 1930s, tanks and armoured cars were treated as a means of short range reconnaissance and infantry support. Large armoured units were not formed; tanks were assigned to infantry divisions.
Nevertheless, even in the early 1930s, many had the opinion that tank units were needed, at least in Manchuria, to rival Japan's main enemy: the Red Army. This was never achieved in practice, and throughout the Sino-Japanese war, tank companies, or even individual tanks, were assigned to infantry units.
Three conflicts influenced Japanese tank theories: the Italian campaign in Ethiopia (1935-1936), the Spanish Civil War (1936-1939), and the Khalkin-Gol conflict in 1939. By 1940, the Japanese considered tanks not only a means of infantry and cavalry support, but a means of penetrating deep into enemy defenses. A new combat manual was written, acknowledging that tanks may perform their own combat tasks. The unit structure was redesigned. Instead of a mixed tank brigade, the Kwantung Army received two tank groups, each of which consisted of three tank regiments. Some infantry divisions received mechanized units.
By the time full-fledged fighting began in the Pacific, the Japanese army had 18 tank regiments, each of which included four tank companies. Tank companies were also assigned to infantry divisions, typically 9 Type 95 Ha-Go. The 1st and 4th special amphibious groups of the Imperial Navy received analogous companies. Independent tank companies were also included in the High Command Reserve.
Tank units were transferred to armies during preparations for an offensive. Two regiments fought with the 14th Army in the Philippines, three with the 15th Army in Thailand and Burma, and with the 25th Army for Malaysia.
In 1942, based on German experience in Africa and Europe, Japan started growing their tank units. Medium tanks were going to be the main strike force. In March of 1942, a decision was made to create tank groups, which were practically tank divisions. Each division would contain two tank brigades, an infantry and an artillery regiment, an engineering battalion, a reconnaissance battalion, and a quartermaster and supply battalion. Each division also had a communications company. Chi-Ha and Type 89 tanks were tasked with supporting infantry. Shinhoto Chi-Ha tanks were tasked with fighting enemy tanks.
In 1943, tank regiments were reformed. Some of them received an extra company, some were reduced in size. In any case, the Japanese were fighting in very specific conditions, which disallowed widespread use of tanks or armoured cars.
When defending, the Japanese used tanks for counterattacks and ambushes. Engaging enemy tanks was only allowed in an emergency situation. By the end of the war, the Japanese high command changed their mind, and tanks were seen as an effective ground anti-tank measure.
After 1941, soldiers of armoured units were prepared to fight in jungles, heat, mountains, without any kind of road infrastructure. Use of tanks in amphibious landings was practiced. Joint force exercises with small groups were held. Against a poorly armed enemy, these tactics were very effective. However, against the US or the USSR, they did not work as well, mainly due to the superior technology of these nations and a large amount of guns that could counter the poorly armoured Japanese vehicles.
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