The ISU 152 , designed as the SU152 in early 1943 was in production by the end of the year, and mounted a 152mm howitzer to provide both infantry support, and an effective counter to the German Panther and Tiger tanks. Heavily armoured this assault gun was a tough nut to crack and was a very effective design. Over 4500 were built by the end of the war, and continued in service into the 1950s.