The Panzerkampfwagen III, commonly known as the Panzer III, was a medium tank developed in the 1930s by Germany, and was used extensively in World War II. The official German ordnance designation was Sd.Kfz. 141. It was intended to fight other armoured fighting vehicles and serve alongside and support the similar Panzer IV, which was originally designed for infantry support. However, as the Germans faced the formidable T-34, more powerful anti-tank guns were needed, and since the Panzer IV had more development potential with a larger turret ring, it was redesigned to mount the long-barrelled 7.5 cm KwK 40 gun. The Panzer III effectively swapped roles with the Panzer IV, as from 1942 the last version of Panzer III mounted the 7.5 cm KwK 37 L/24 that was better suited for infantry support. Production of the Panzer III ceased in 1943. Nevertheless, the Panzer III's capable chassis provided hulls for the Sturmgeschütz III assault gun until the end of the war.
The 501st Heavy Panzer Battalion (German: "schwere Panzerabteilung 501"; abbreviated: "s PzAbt 501") was a German heavy Panzer Abteilung (an independent battalion-sized unit) equipped with heavy tanks. The battalion was the second unit to receive and use the Tiger I heavy tank, changing to Tiger IIs in mid-1944. It fought and surrendered in Tunisia, reformed in September 1943, then fought on the Eastern front; destroyed, it reformed with Tiger IIs in July 1944, then mostly deactivated on 11 February 1945.