T-34-85 tank was an upgraded version of T-34. It was designed in 1943 after the battle of Kursk. It was a response to the appearance of new versions of Panzer IV, and the newest tanks – Panzer V “Panther” and the Panzer VI “Tiger” in Wehrmacht.
In 1943 it was clear that old T-34 couldn’t compete with those models, due to its weaker gun. In Battle of Kursk, T-34 with its 76mm gun was not able to penetrate the armour of many upgraded German tanks. Especially it was practically useless against Tiger I with its thick armour and powerful 88mm gun.
It was decided to replace 76 mm with new 85 mm antiaircraft gun. T-34 armour was also improved. As the result, Soviet Army has got the great tank with high mobility and doubled main gun’s armour penetration and turret frontal armour thickness.
It was a very cheap tank for the industry, so by May 1944, T-34-85 production had reached 1,200 tanks per month. During World War II 22,559 T-34-85 tanks were constructed. For the comparison, only 6,557 Panther types and 2,027 all Tiger types were built for the same time.
After 1945, construction and use of T-34-85 was not stopped. Many countries had these tanks in their armies. Some of them were still used at least until 1997. It is a practical evidence of unique longevity of this model.