Fully enclosed casemates on the Germans' "Sturmgeschütz" assault guns, from the beginning of the war, set a pattern used later by the similarly fully enclosed "Jagdpanzer" casemate-style tank destroyers, with the Soviets' similar "Samokhodnaya ustanovka" (SU) assault guns being used for the same dual-purpose roles. However, the lack of a rotating turret had limited the gun's traverse to a few degrees. This meant that the entire tank normally had to be turned onto its target by the driver, a much slower process than simply rotating a powered turret. If the vehicle became immobilized due to engine failure or track damage, it could not rotate its gun to counter opposing tanks, making it highly vulnerable to counterfire. This vulnerability was later exploited by opposing tank forces. Even the largest and most powerful of German tank destroyers were found abandoned on the field after a battle, having been immobilized by one or more hits by high explosive (HE) or armor-piercing (AP) shells to the track or front drive sprocket.