In the second half of the 1940s, the U.S. was carrying out unhurried work on a heavy tank and had not moved beyond the prototype phase. The Korean War was a strong impetus to progress, and the early 1950s saw the appearance of the T43 heavy tank, which transformed into the serially produced M103 heavy tank. Work then began on designing heavier tanks, and the H3 heavy tank was among the presented concepts. The U.S. clearly drew upon experience of the French AMX 50 in its creation. The vehicle was equipped with an oscillating turret and an autoloader but remained an original design—this also concerned the turret. The hull was made as low as possible. In addition, the tank had a high power-to-weight ratio. Work on the H3 heavy tank did not go beyond design proposals.