Japanese tanks of World War II M4 Sherman medium tank. Originally, the next tank in development to replace the Type 1 Chi-He was the Type 4 Chi-To medium tank. However, the development of the Type 4 Chi-To was delayed, and a "stopgap tank" was needed. Development of the Chi-Nu started in May 1943 and was finished by October. The low priority given tanks, along with the raw material shortages meant that the Type 3 did not enter production until 1944. It was the last design based directly on Type 97 lineage. The Chi-Nu retained the same chassis and suspension of the Chi-He, but with a new
History of the tank was considered to be up to 10 tons, the medium (produced by the British) was roughly between 10 and 25 tons, and the heavy was over 25 tons. For World War II, increased weights resulted in the light tank being over 20 tons, the medium over 30, and the heavy, developed toward the end of the war, over 60 tons. During the period between the world wars, the weights of the classifications varied generally within these extremes. The U.S. National Defense Act of 1920 placed the Tank Corps under the Infantry. The Act's stipulation that "hereafter all tank units shall