The Panzer IV is normally described as having been the mainstay of the German tank forces during the Second World War, but that is actually somewhat misleading. While it is true that the Panzer IV was the only German tank to remain in production for the entire duration of the war, for the first three of those years it was a close support weapon produced in relatively small numbers. It was only after the appearance of the long-gun armed Ausf F2 in the summer of 1942 that the Panzer IV became a potent tank killer, and its heyday came during 1943, when for a short period between the gradual disappearance of the Panzer III and the entry into service of the Panther it was indeed the backbone of the Panzer forces.
The original Panzer IV was designed to operate in support of the Panzer III. That tank, initially armed with a 3.7cm KwK L/46.5 gun and firing armour piercing rounds, was expected to act as the German Armyís tank killer. The Panzer IVs would follow behind, and would use their 75mm howitzer firing high explosives to destroy soft skinned targets such as enemy anti-tank guns, which were not particularly vulnerable to armour piercing shells.The Panzerkampfwagen IV Ausf D was the fourth production version of the Panzer IV medium support tank, and saw the first increase in the thickness of the side and rear armour. The 15mm armour of the Ausf A-C was replaced by 20mm armour.
Of the original order for 248 tanks, 229 were completed as Panzer IVs, while the remaining chassis were used to produce two self-propelled guns, sixteen bridge laying tanks and one ammunition carrier. Late Ausf Ds were produced with 30mm armour plates bolted and welded to the front of the superstructure and hull, and 20mm plates bolted to the sides. The production of the Ausf D meant that by May 1940 every tank detachment could have a medium tank company of between six and eleven Panzer IVs, and on 10 May 1940 the Panzer divisions that were to take part in the campaign in the west were equipped with 280 Panzer IV Ausf A-Ds. The Ausf D served in France, the Balkans, Africa and Russia, remaining in combat until the last survivors were destroyed early in 1944. A number of Ausf Ds were withdrawn from the front line in 1943, rearmed with longer 7.5cm KwK L/48 guns and used for training purposes.