KV

The KV series is a family of heavy tanks produced and fielded by the Soviet Union from 1939 to 1943. These proved to be nasty surprises for the invading German forces in Operation Barbarossa, as they were practically immune to the guns equipped on the Panzer-III and Panzer-IVs of the time. Only the 8.8cm Flak gun set on direct fire could penetrate their thick armor.

Their battlefield roles were eventually supplanted by T-34s and the IS series of tanks, respectively.