Built in 1944, the IS-2 (IS-122) heavy tank was a modification of the IS-1. It had a 120 mm glacis plate that was much simpler to cast. Heavy tank regiments of the Elite Soviet Guards used the IS-2 extensively in their assaults on the fortress cities of Budapest, Breslau, and Berlin. The IS-2 shielded tank is a modification featuring additional meshed screens to increase the vehicle's survivability in urban warfare.