T-44 followed by T-54/55
The T-44 was a medium tank first developed and produced near the end of World War II by the Soviet Union. It was the successor to the T-34, offering an improved ride and cross-country performance, along with much greater armor. Designed to be equipped with an 85 mm main gun, by the time it was fully tested the T-34 had also moved to this weapon. Both tanks offered similar performance, so introducing the T-44 was not considered as important as increasing T-34 production. Fewer than 2,000 T-44s were built, compared to about 58,000 T-34s. Although the T-44 was available by the end of the war, it was not used in any battle. It was 1 ton lighter than the T-34-85 and slightly faster. The T-44 was heavily influential on the design of the T-54/55 main battle tank, most notably the removal of side sloping, thick frontal armor, and a low profile. Also notable was the T-44-100, a 100mm D-10T-armed prototype, which would be the same 100mm gun mounted on the T-54/55, bar some minor changes.
Attempts were made to improve the T-44's armament with a new 122mm gun, but the turret proved to be very cramped and the rate of fire was poor, on the order of three rounds per minute. Design work on a slightly enlarged version of the T-44 began during the war and a prototype was produced in 1945. This newer design entered production in 1947 as the T-54/55 series of medium tanks, the most-produced tank series of all time.