A Soviet GAZ-MM 4 x 2 cargo truck drives past a line of ISU-152 assault guns in Lvov, in the Ukraine, in July 1944. The photograph gives a good view of the chassis' running gear, with KV-l's spoked wheels rather than the disc wheels used on the T-34 and its variants.
The ISU-122 and ISU-152 were used in Independent Heavy Self-Propelled Artillery Regiments, which were awarded the Guards honorific after December 1944. By the end of the war there were 56 such units. Generally attached to the tank corps, they were deployed in the second echelon of an assault, providing long-range direct, and on occasion indirect, fire support to tanks in the first echelon, targeting German strongpoints and armoured vehicles. They were also vital in providing defensive antitank and artillery support for infantry.
The dual role of the ISU-152 is demonstrated by fighting on 15-16 January 1945 in the area of the Polish village of Borowe. Elements of Marshal K. K. Rokossovsky's 2nd Byelorussian Front were vigorously counterattacked by the Panzergrenadier Division Grossdeutschland. The initial German assault proved very effective, driving the Soviets back. As elements of the spearhead 2nd Fusilier Battalion consolidated their gains, the 3rd Fusilier Battalion moved through them towards Soviet positions around Borowe. Both battalions soon came under high explosive and armour piercing fire from SU-152s of the 390th Guards Independent Heavy Artillery Regiment. The 3rd Fusilier Battalion and its supporting armour did manage to secure the town on 16 January under intense antitank fire from SU-152 guns supported by rocket artillery. But success was short-lived, as Soviet success in other areas collapsed the front, forcing a withdrawal. Even so, as one soldier of the 2nd Battalion starkly described, being under fire from 'Black Pigs' was harrowing:
Black detonations in front of us, behind us, beside us - and we lay on the frozen ground with no possibility of crawling into it ... Now and then someone raised his face a little beneath his steel helmet to see if the other was alive. For an hour there was nothing but the sound of incoming and exploding shells.
During the 1st Ukrainian Front's breakout from the Sandomierz bridgehead over the river Vistula in central Poland, Marshal I. S. Konev used several ISU-equipped regiments to enhance the devastating opening barrage of 450 medium- and heavy field guns per kilometre of front. When the assault troops moved forwards, poor weather and lack of visibility in the harsh winter conditions made it difficult to operate with air and artillery support.
However, the momentum of the attack was maintained through the close fire support provided by ISU-122 and ISU-152s operating alongside the infantry. The result was an advance of 12km (7.45 miles) on the first day, carrying Soviet forces through the forward German tactical defences and creating the conditions for the release of the second echelon tank armies with their fast medium T-34s to exploit deep into the enemy's operational rear. This pattern of attack was a thorough vindication of pre-war Soviet ideas about the interaction of heavy and medium armour in carrying out the deep battle and deep operation respectively.