The T-35 was a Soviet multi-turreted heavy tank of the interwar period and early Second World War that saw limited 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 complement the contemporary T-28 medium tank; however, very few were built.