 Complete the following phrase:  The barrage remained in Soviet doctrine in World War II, where the creeping barrage by massed guns was the standard accompaniment to an infantry assault. The Soviet artillery had plenty of guns. Some 7,000 guns and mortars were massed for the counter-attack at the battle of Stalingrad, and huge bombardments remained standard for the rest of the war. During the Soviet advances in 194445, the tactic was used extensively throughout the Eastern Front such as the VyborgPetrozavodsk Offensive, the Battle of the Seelow Heights, and the 