Sturmgeschütz III
The Panzer III's armor was upgraded to 70  mm by additional plates, and spaced armor was introduced to protect against hollow charge (a.k.a. high-explosive anti-tank) attacks. However the first Panzer IV tanks with 75 mm L/48 cannon marked the end of the Panzer III's role as the German main tank. Eventually, Panzer III production was ended in August 1943 with the Ausf. M (a conversion of older types), the vehicle having been up-gunned to a 75 mm L/24 gun and downgraded to a support role. The Panzer III chassis continued in production until the end of the war as the base for a range of special purpose vehicles like the Sturmgeschütz III.