Comparing: O-I vs. KV-85

Development of the superheavy tank was started after the Battles of Khalkhyn Gol in 1939. The vehicle was designed as a maneuverable fire unit that was unprecedented in scale—its hull alone weighted 100 tons. Only one prototype was built, without a turret and made of construction steel. Trials were discontinued due to the unreliable engine; at the end of 1944, the prototype was scrapped. The 15-cm howitzer was to be mounted on the tank after the assemble.

A further development of the KV-1S tank. Unlike the previous modification, the KV-85 had enhanced armament. The vehicle was developed in the spring of 1943 at the Chelyabinsk Kirov Plant. The tank entered service on August 8, 1943, and was mass produced until September, with a total of 148 vehicles manufactured. The KV-85 was used by the breakthrough armored regiments of the Red Army.