The Soviets realized in the Russo-Finnish War that cumbersome, multiturreted "land battleships" were tactically limited. They borrowed the chassis from one of such tanks and developed the heavy tank known as the KV-I. A monstrous vehicle packing a 76.2mm gun and three MGs, it had a nearly impenetrable hide up until the introduction of 88mm guns into the battlefield. It had a bow MG, a coaxial MG, and a MG in the rear of the turret (most likely to defend against infantry assaults from the rear). It was later upgraded to a much more potent yet less common KV-85 with a lower, wider turret mounting an 85mm gun.