The KV-1 is a Soviet heavy tank, named after MarshalKliment Voroshilov. The KV-1 was first tested in the Winter War and in 1940 production was increased. At the beginning of Operation Barbarossa, the German invasion of the Soviet Union in 1941, the Red Army had 639 KV-1s. Initially, German tanks were incapable of penetrating the armour and at one point a large German armoured group was delayed for 2 days by a single KV-1 near Ostrov.
