Sturmtiger (German: "Assault Tiger" ) was a World War II German assault gun built on the Tiger I chassis and armed with a 380mm rocket-propelled round. The official German designation was Sturmmörserwagen 606/4 mit 38 cm RW 61. Its primary task was to provide heavy fire support for infantry units fighting in urban areas. The few vehicles produced fought in the Warsaw Uprising, the Battle of the Bulge and the Battle of the Reichswald. The fighting vehicle is also known under a large number of informal names, among which the Sturmtiger became the most popular.