Therefore, a ring of ventilation shafts was put around the barrel which channeled the exhaust and gave the weapon something of a pepperbox appearance. Due to the bulkiness of the ammunition, only fourteen rounds could be carried internally, of which one was already loaded, with another in the loading tray. The rest were carried in two storage racks. To help with the loading of ammunition into the vehicle, a loading crane was fitted at the rear of the superstructure next to the loading hatch. Even then, the entire five-man crew had to help with the loading. It was intended that each "Sturmtiger" would be accompanied by an ammunition carrier built on the same Tiger I chassis, but only one carrier was completed. Located at the rear of the loading hatch was a "Nahverteidigungswaffe" launcher which was used for close defence against infantry in addition to a frontal mounted 7.92 mm MG 34 machine gun. The "Sturmtiger" was intended to serve as a heavy infantry support vehicle, rendering assistance with attacks on heavily fortified or built-up areas. By the time the first "Sturmtiger" were available, however, Germany had lost the initiative, with the Wehrmacht being almost exclusively on the defensive rather than the offensive. Three new Panzer companies were raised to operate the "Sturmtiger": "Panzer Sturmmörser Kompanien (PzStuMrKp)" ("Armored Assault Mortar Company") 1000, 1001 and 1002. These originally were supposed to be equipped with fourteen vehicles, but this figure was later reduced to four each, divided into two platoons. "PzStuMrKp" 1000 was raised on 13 August 1944 and fought during the Warsaw Uprising with two vehicles, as did the prototype in a separate action, which may have been the only time the "Sturmtiger" was used in its intended role. "PzStuMrKp" 1001 (commanded by Captain von Gottberg) and 1002 (commanded by Lieutenant Zippel) followed in September and October. Both "PzStuMrKp" 1000 and 1001 served during the Ardennes Offensive, with a total of seven "Sturmtiger". After this offensive, the "Sturmtiger" were used in the defence of Germany, mainly on the Western Front. During the battle for the bridge at Remagen, German forces mobilized Sturmmörserkompanie 1000 and 1001 (a total of 7 units) to take part in the battle.