Numerically, the PzKpfw IV was the most important German tank of the war and of the fighting in Normandy, where the latest Ausf Hand Ausf J were the most common. Among the units in Normandy there were two exceptions to the tank's usual allocation to the II. Abteilung of a panzer regiment: in Panzer Regiment 33, where I. Abteilung was equipped with the PzKpfw IV, and in Panzer Regiment 22, where both I. and II. Abteilung were equipped with it.
On paper, seven of the eleven Abteilung were at normal strength, with 22 tanks per Kompanie; but no more than six Abteilung went into action with a full complement of between 17 and 22 tanks per Kompanie.
From 1934 the Armaments Ministry had been thinking of a medium tank with a 7. 5cm gun, and the first design, perfected by Krupp, appeared in 1936 under the codename 'I/BW.' This was the PzKpfw IV Ausf A, which was followed by Ausf B, C and D in small numbers up till 1939.
It was not until after the Polish campaign, at the end of 1939, that the PzKpfw IV made its real debut - with the introduction of the Ausf E. Almost 300 PzKpfw IVs took part in the blitzkrieg of 1940 and 280 came off the assembly lines that year, rising to 480 in 1941. At this time, it was the Germans' heaviest operational tank but, as yet, it had a 7. 5cm gun with a 24-calibre barrel.
The Ausf F of 1941 was produced in collaboration between Krupp and Rheinmetall-Borsig, and possessed a modified suspension and wider tracks. The F2 which followed was, at last, armed with a 43-calibre 7. 5cm gun which, in 1942, when it was given a muzzle brake, became the Ausf G (SdKfz 161/1). The armour-plate had been regularly thickened, and an in- novation was the way in which warm water in the cooling system was transferred from one radiator to another to help in starting the engine.
In June 1942 - when it began to be fitted with a 48-calibre gun and the frontal armour of its hull had been supplemented to 80mm thickness - the PzKpfw IV had almost reached its definitive form.
The exhaust identifies this model as a late-type Ausf J. The main difference between the Ausf H and J was that the former had a small auxiliary engine at the rear serving as a generator for the electric turret traverse. (The turret was manually driven on the Ausf J.) The gun is a 7.5cm KwK40 L/48 - 48 standing for the length which was 48 times the calibre, Le. 48 x 75mm.
Ausf H (SdKfz 161/2)
1943 was a turning point for the PzKpfw IV, when the backbone of the panzer units, the PzKpfw III, ceased production and it was a question of whether the PzKpfw IV should stop as well. The Tiger was beginning to assert itself and deliveries had started of the Panther.
The proposal to stop producing the PzKpfw IV in favour of the new and larger tanks encountered vehement opposition from several generals, among them the Inspector General of Armoured Troops, Guderian, who maintained that only the PzKpfw IV could be turned out in large numbers. The Tiger was at that time being produced at the rate of just twenty-five a month and the Panther was as yet untested in battle.
The outcome was an order for all-out production of the PzKpfw IV. There were further threats to the tank's existence towards the end of the year when Organisation Todt proposed using the turret for fortification points and another suggestion was that a halt should be called to increase the manufacture of assault guns, but nothing came of this and more than 3,000 were completed by the factories during the year - almost as many as were to be built from then till the end of the war.
Whilst the arguments were being pursued, in March 1943 the Ausf H made its appearance. Mechanically, it differed from previous models by the replacement of the ZF SSG 76 gearbox with the ZF SSG 77 which had earlier been fitted in the PzKpfw III. Externally, the main difference between the Ausf H and the G was the presence of Schürzen - or skirts - on the hull sides, late models of the Ausf G having already been given turret skirts. This soft steel, 5mm-thick armour-plate was originally intended to break up Soviet anti-tank rifle projectiles prematurely on the outside of the tank itself - between the skirt and the tank - cancelling out the shell's penetrating power. At first the hull plates were fixed soundly onto lengthwise rails; then this was abandoned for slotting them on brackets welded to the rails. This way the plates came away more easily on impact and with less chance of getting jammed in the tracks and damaging the running wheels.
Observation slits for the loader and gunner at the side of the turret were dispensed with as redundant; the aerial was now fixed on the left at the rear of the hull; a new driving sprocket and idler wheel with 'open' spokes were introduced; 30mm frontal armour-plate was first bolted on but then soon welded on; the driver's and radio-operator's side observation ports soon disappeared in their turn, and the cupola hatch reverted to a single section.
Ausf J (SdKfz 161/2)
The last development of the PzKpfw IV - the Ausf J - came out a year later in March 1944. To increase its operational range, the electric turret travers- ing mechanism was removed and the space saved used for an extra fuel tank. Thereafter the turret was operated by a two-speed handwheel. The external 2- stroke engine that worked the electric generator was also removed - its absence being the clue in identifying the Ausf J.
Possibly some two-thirds of the PzKpfw IV battalions in Normandy were equipped with the Ausf H and the remainder with the Ausf J. There were also around half a dozen ancient Ausf Bs or Cs in II. Abteilung of Panzer Regiment 22 which were most likely used for training or as OP tanks but were nonetheless sent into action. Almost certainly, some units must still have possessed a few Ausf Gs; and some Ausf Hand Ausf J turrets housed the Ausf G 43-calibre gun which was 38cm shorter than the 48-calibre. The PzKpfw IV was mechanically well tried and very reliable; it was available in large numbers and had a good operational range - particularly the Ausf J. By this stage of the war, however, its armour was inadequate and its speed was slow in relation to its weight.