During the Second World War, the Red Army of the Soviet Union deployed five shock armies ( – singular: ) between 1941 and 1945. Many of the units, which spearheaded the Soviet offensives on the Eastern Front from the Battle of Stalingrad (1942–1943) to the Battle of Berlin (1945), were shock armies. Shock armies had high proportions of infantry, engineers, and field artillery, but with less emphasis on operational mobility and sustainability. Soviet shock armies were characterized by a higher allocation of army-level artillery units to break German defense positions by weight of fire, and often had heavy tank regiments or heavy self-propelled gun regiments to add additional direct fire-support. Once a shock army had made a breach in an enemy tactical position, more mobile units such as tank and mechanized corps would insert themselves through the shock army's positions with the mission of penetrating deep into the enemy rear area. By the end of the war, though, Soviet guards armies typically enjoyed superior artillery support to that of the shock armies.