The Kliment Voroshilov (KV; Russian: Климент Ворошилов, КВ) tanks are a series of Soviet heavy tanks named after the Soviet defence commissar and politician Kliment Voroshilov who operated with the Red Army during World War II.

The KV tanks were known for their heavy armour protection during the early stages of the war, especially during the first year of the German invasion of the Soviet Union.

The German Wehrmacht at that time rarely deployed its tanks against KVs, as their own armament was too poor to deal with the "Russischer Koloss" – "Russian Colossus".

The T-35 conformed to the 1920s notion of a "breakthrough tank" with very heavy firepower though its armour protection was lacking and it suffered from poor mobility.

The designers of the SMK independently drew up a single-turreted variant and this received approval at the highest level.

[10] When the Soviets entered the Winter War, the SMK, KV and a third design, the T-100, were sent to be tested in combat conditions.

The KV's heavy armour proved highly resistant to Finnish anti-tank weapons, making it more difficult to stop.

During the war, the Soviets found it difficult to deal with the concrete bunkers used by the Finns and a request was made for a tank with a large howitzer.

While their frontal armor was sufficient to deflect anti-tank fire, German troops were able to outflank them and destroy them with explosive charges or lure them to within point-blank range of direct-fire artillery.

It also had serious flaws: it was difficult to steer; the transmission (which was a twenty-year-old Holt Caterpillar design)[13] "was the main stumbling block of the KV-1, and there was some truth to rumors of Soviet drivers having to shift gears with a hand sledge";[13] and the ergonomics were poor, with limited visibility.

As appliqué armour and other improvements were added without increasing engine power, later models were less capable of keeping up to speed with medium tanks and had more trouble with difficult terrain.

[13] It took field reports from senior commanders "and certified heroes", who could be honest without risk of punishment, to reveal "what a dog the KV-1 really was".

The KV-1's side (favorable approach: 30° at 300–500 m distance), top, and turret armor could also be penetrated by the high-velocity Mk 101 30 mm cannon carried by German ground attack aircraft, such as the Henschel Hs 129.

In 1943, it was determined that this gun could not easily penetrate the frontal armour of the new Tiger, the first German heavy tank, one of which was captured near Leningrad.

[citation needed] In response to criticisms, the lighter KV-1S was developed, with thinner armor and a smaller, lower turret in order to reclaim some speed.

This was a KV-1S with the new turret from the Object 237 (IS-85) still in development, mounting the same 85 mm D-5T gun as the SU-85 and early versions of the T-34-85 (not yet in production at the time).

The 85 mm proved capable of penetrating the Tiger I from 1000 m and the demand for it slowed production of the KV-85 tremendously, only 148 were built between August and October 1943.

The 122 mm D-25T used a separate shell and powder charge, resulting in a lower rate of fire and reduced ammunition capacity.

During the night, German combat engineers attempted to destroy the tank with satchel charges and failed, despite possibly damaging the tracks.

[36] General Erhard Raus was commander of the Kampfgruppe of the 6th Panzer Division, the unit delayed by the lone vehicle.

[f] He described it as a KV-1, which was damaged by several 8.8 cm anti-tank gun shots fired from behind the vehicle while it was distracted by Panzer 35(t) tanks from Panzer Battalion 65, and the KV-1 crew were killed by members of a pioneer unit who pushed grenades through two holes made by the gun while the turret began moving again, the other five or six shots having not fully penetrated.

[37][a] On August 14, 1941, the vanguard of the German 8th Panzer Division approached Krasnogvardeysk (Gatchina) near Leningrad (St Petersburg), and the only Soviet force available at the time to attempt to stop the German advance consisted of five well-hidden KV-1 tanks, dug in within a grove at the edge of a swamp.

The Germans falsely assumed that their lead tank had hit an anti-tank mine and failed to realize that they had been ambushed.

Although the Germans correctly guessed the direction of fire, they could only spot Lieutenant Kolobanov's tank, and now attempted to engage an unseen enemy.

German tanks moving off the road bogged down in the surrounding soft ground, becoming easy targets.

Later, former Captain Zinoviy Kolobanov was again decorated by Soviet authorities, despite having been convicted and downgraded after the Winter War for "fraternizing with the enemy."

Kolobanov's feat was so great that when telling his story after the war, civilians and military personnel alike did not believe him, sometimes laughing in disbelief while listening to his tale.