A German infantry corporal in the trenches during WWI had been impressed by the capabilities of the tank. His name was Adolf Hitler. Under his rule the Panzer was developed,and of this series,the Panzer IV was by far the most important and could fight on equal terms with anything but some of the heavier Russian Tanks. One of the major reasons for the eventual German defeat was the Soviet T-34 medium tank,generally thought of as the best all-round tank of WWII. Early British WWII medium tanks were rather lightweight,and the first true medium tank was the Vickers Valentine. The Allies eventually developed the M4 Sherman to match the Panzer IV,but by this time the Germans had developed more advanced machines of their own. Despite this,the Sherman played a decisive role in winning the war,due mainly to the sheer volumes produced. The old Sherman was followed after the war by the M48 and M60,and then first entering service in 1965 but still going strong,the S-tank. This is almost certainly the end of the medium tank,since more recent weapons have resulted in the evolution of much heavier battle tanks designed to cope with helicopters and other aircraft.