The T-34 was a Soviet medium tank which had a profound and permanent effect on the fields of tank tactics and design. First deployed in 1940, it has often been described as the most effective, efficient, and influential design of World War II.
At its introduction, the T-34 possessed the best balance of firepower, mobility, protection, and ruggedness of any tank, although its initial battlefield effectiveness suffered from the unsatisfactory ergonomic layout of its crew compartment, scarcity of radios, and poor tactical employment. Its 76.2 mm (3 in) high-velocity gun was the best tank gun in the world at that time; its heavy sloped armour was impenetrable by standard anti-tank weapons; and it was very agile.
Though its armour and armament were surpassed later in the war, when they first encountered it in battle in 1941 German tank generals von Kleist and Guderian called it "the deadliest tank in the world."