The U.S. Army’s Tactical and Technical Trends (Vol. I, No. 11: July 1943) quoted Red Army sources,
The Germans make extensive use of self-propelled guns as assault artillery. Their most important mission is to destroy the opposition’s antitank and heavy infantry weapons… Assault batteries, which are assigned a limited number of targets, have the mission of supporting the attacks of the infantry, and of destroying the opposition’s heavy infantry weapons and strong points disclosed during the attack. In supporting tank attacks, the self-propelled artillery assumes some of the normal tasks of heavier tanks, including the destruction of antitank guns.
While the German Army was largely a horse-drawn army, the Germans focused, and relied on, armored vehicles for speed, mobility and shock.