T20 Medium Tank T20 Medium Tank The Medium Tank T20 was part of a series of medium tanks designed by the United States during the Second World War, to be the successor to the Medium Tank M4 "Sherman", and culminated in the M26 Pershing. Almost immediately after the M4 Sherman was standardized, the US Ordnance Department started work on a successor. The Ordnance Department had already been working on heavily armored infantry tank design for the British, using M4 parts. The new project was started on the 25 May 1942, it was originally designated M4X. Starting with the T20, the Ordnance Department initially
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