The KV series of tanks were a result of extensive design competitions in the mid to late 1930's. The T-35 with 2 Turrets was finally revised to a Tank with a single Turret and thicker Armour and so was born the KV-1. Kliment Voroshilov was then the Soviet Defense Minister & Commissar so his name was used for the early model KV's. There were about 500 KV's in service when the Germans invaded in June 1941 along with about 1000 T-34's which were far superior to anything the Germans had at the time. Left to Right. KV-1 of 1940. KV-1E of 1941 & KV-1 of 1942.