The Kliment Vorishilov heavy tank was designed in 1938 with a hull that sported a heavily sloped glacis plate that led to a shallow superstructure, which was topped by a heavy turret. Armament consisted of a 76.2mm gun, to which was affixed a coaxial machinegun, plus another two machineguns, one in the turret’s rear, and at the front left of the hull. Because of mounting international tensions and the urgent need for a heavy tank, the KV was rushed into production in 1939, notwithstanding mechanical issues with its transmission system, and an engine whose output was not equal to the KV’s 45 tons. The result was a heavily armed and armored tank, but one that was slow and prone to breakdowns.
Despite its mechanical issues, the KV, along with the T-34 medium tanks, came as a shock to the Germans when they first encountered them. The heavily armored KV-1 proved practically invulnerable to the Panzer III’s 37mm or 50mm guns, and to the Panzer IV’s 75mm short-barreled gun. At an engagement in Raseiniai, a single KV-1 tank halted the 6th Panzer Division for an entire day, shrugging off German shells until an enterprising German soldier finally destroyed it with explosives.
Until German tanks were upgraded with more powerful guns, the only way to destroy a KV was via enterprising infantry sneaking up on it, an 88mm flak gun, or an aerial strike. Fortunately for the Germans, the Soviets had only about 500 KV-1 tanks at the start of Operation Barbarossa, and poor training and inept leadership prevented the Red Army from taking advantage of its decided edge in tanks.
Once the Soviets learned the basics of modern armored warfare, they began concentrating KVs in dedicated assault regiments and using them more efficiently. Taking advantage of the KVs heavy armor and high-powered main gun, KV-1 units spearheaded Soviet offensives in 1942 and 1943, tasked with smashing through German lines and ripping open holes for agile T-34s to pour through and exploit.
Although effective, the KV was nonetheless phased out and its production was halted in 1943 because it was not as cost-effective as the T-34, which was easier to produce, and could do most of the KV’s tasks just as well or better at a fraction of the cost. The KV platform instead became the launching pad for the even more powerful and effective Iosef Stalin (IS) heavy tanks.