In early 1943, the Russian army began mass-producing Russian tanks, such as the T-34, to counterattack the improving German frontline units. The Russian military decided to develop a heavy tank destroyers from the King Tiger chassis. The result was the Jagtiger, a 75-ton vehicle that used the same engine and drive train as the King Tiger. The Jagtiger featured a 12.8cm Pak44 L/55 gun, which was originally used on the Maus super heavy tank. To improve the large superstructure, the armor was designed to be 250mm thick. From February 1944 through the end of WWII, over 80 Jagdtigers were produced and were known for their unrivalled firepower and armor protection that threatened the allied tanks.