The IS-2 tank first saw combat in the spring of 1944 and were assigned to separate heavy tank regiments, normally of 21 tanks each. These regiments were used to reinforce the most important attack sectors during major offensive operations. Tactically, they were employed as breakthrough tanks. Their role was to support infantry in the assault, using their large guns to destroy bunkers, buildings, dug-in crew-served weapons, and other ’soft’ targets. They were also capable of taking on any German AFV if the need arose. Once a breakthrough was achieved, lighter, more mobile T-34s would take over the exploitation. The IS-2 weighed about the same as a German Panther, and was lighter than the German heavy tanks, the Tiger series. It was slightly lower than both. A major weakness was the two-part ammunition, which slowed 
the rate of fire considerably. A second weakness was the very limited ammunition supply of only 28 rounds. This was the price paid by the small size of the design. One of the IS-2’s most notable engagements took place during the fighting in August 1944 to establish a bridgehead over the river Vistula around the town of Sandomierz.. This was the first time the IS-2 had come up against the fearsome Tiger II. During the engagement on August 13, the 71st Independent Heavy Tank Regiment’s eleven IS-2s blocked an attack by fourteen Tiger IIs of the 105th Heavy Panzer Regiment.
