Medium tank

Sherman medium tank from World War II, the workhorse of U.S. armoured forces

Medium tanks of the interwar period included the British Vickers Medium Mark II and the Soviet multi-turreted T-28. In the period leading up to World War II, the British stopped using the term Medium for their tanks as the new philosophy of Cruiser tank and Infantry tank which defined tanks by the role rather than size came into use.

There were medium tanks that focused on anti-infantry capabilities (such as in World War II: the Panzer IV short-barrel, and the M4 Sherman), and medium tanks which were more focused on the anti-tank role, mounting high-velocity tank guns. The French cavalry tanks (Chars de Cavalerie) focused on speed in addition to power and protection of the other designs. They were similar to what other countries called medium tanks.

When Soviet tank designers were preparing a successor to the BT tank series, they combined its excellent mobility with thick, sloped armour and the unprecedented firepower of a 76 mm high-velocity gun. The result was the T-34 medium tank, whose superb capabilities shocked the German Wehrmacht when it invaded the Soviet Union. The lessons of Blitzkrieg, first employed by the Germans and eventually adopted by other nations, found their best expression in formations of mutually-supporting medium tanks and motorised infantry. The traditional view of infantry and cavalry tank roles was rendered obsolete.

Panzer IV German medium tank

Both the Soviet Union and the United States benefited from their ability to manufacture a well-balanced medium tank in very large numbers - around 84,000 T-34s and 49,000 M4 Sherman tanks were built during the war period. https://en.wikipedia.org/wiki/T-34

During and after World War II, the roles of light tanks were gradually taken over by less-expensive armoured cars and specialised reconnaissance vehicles. Heavy tanks, having shown their limitations in combat, experienced a limited post-war arms race of progressively more heavily armed and armoured designs. With the rise of more sophisticated anti-tank missile weapons, to which heavy tanks had demonstrated high vulnerability, these too were eventually phased out.

With advances in technology, aspects such as mobility, armour and weaponry pushed the medium tank to form the core of a country's armoured fighting capability, eventually merging into the Main Battle Tank. Simpler and more economical self-propelled guns, and later anti-tank guided missiles, came to fulfil some fire-support and anti-tank roles, thus shifting the tactical approach how tanks were used.

In the 1990s, medium tanks continued to be used, such as Canadian medium tanks in Kosovo in 1999 which were much better suited to the poor roads and soft ground than the French armoured cars there, but were still able to move along narrow streets and over lighter bridge classifications than the much heavier American Abrams tanks.