The T-35 was a Soviet multi-turreted heavy tank of the interwar period and early Second World War that saw limited production and service with the Red Army. Often called a land battleship, it was the only five-turreted heavy tank in the world to reach production, but proved to be slow and mechanically unreliable. Most of the T-35 tanks still operational at the time of Operation Barbarossa were lost due to mechanical failure rather than enemy action. It was designed to replace the T-28 at the time, however, very few were built. Outwardly, it was large; but internally, the spaces were cramped with the fighting compartments separated from each other. Some of the turrets obscured the entrance hatches. Turrets were located at different levels and equipped with guns and machine guns. The crew consisted of 9-11 persons.