The Sturmgeschütz made a valuable contribution to the success of Operation Barbarossa, but, despite the initial successes, by late 1941 it was apparent that the German armoured force as a whole was seriously under-gunned. The armoured forces of the Wehrmacht were in danger of being swamped by the new Russian T-34 tanks.
We have seen that the short 75mm gun of the Sturmgeschütz was really designed to fire low velocity, high explosive shells in support of infantry formations, and although it used the relatively small chassis of the Panzer III, the fact that it had no turret allowed the Stug to be up-gunned to incorporate the deadly long-barrelled 75mm gun, which could not be fitted to a Panzer III.
With this gun, the Sturmgeschütz was now a match for the T-34, and much more than an infantry support weapon. It was now apparent that, with its low silhouette, the Stug was a much harder target to hit than the Russian T-34. The sloped armour also helped to deflect shots away from the vehicle, and the scales gradually began to tip back in Germany’s favour during the fierce tank battles of 1942.
This much-needed upgrade was first incorporated into the Sturmgeschütz Model F in 1942. The long barrelled L/43 gun gave the armour piercing shells fired by the Geschutz a much higher muzzle velocity and therefore a far greater tank killing capability than the 50mm gun of the Panzer III. It was now obvious that the Panzer III had evolved as far as it could and the model was phased out. From 1943 the Panzer III chassis was used exclusively for the manufacture of Sturmgeschütze, production of which continued right up to the last days of the war.
The pressure of battle on the Eastern Front ensured that, almost by accident, the German forces had evolved a very successful example of a new breed of fighting vehicle - the Panzerjäger or Tank Hunters. It was in this role that most Sturmgeschütze were to be employed for the rest of the war, and 20,000 enemy tank kills were claimed by assault gun crews up to the early months of 1944.
The Sturmceschutze manual stressed time and time again the need for the gun to be stationary when firing. In this way the highest level of accuracy was achieved. When the commanders heeded this request, the results were devastating.
In a mobile battle, where every second counts, the lack of a turret was a very real disadvantage, but Sturmgeschütze crews learned to adopt defensive tactics designed to lure Russian tanks into carefully constructed killing grounds.
The new tactics certainly worked, and in early 1943 there was another increase in gun power with introduction of the long 48 calibre gun, which gave extra velocity.
It was this new gun which equipped the definitive Sturmgeschütze, the Model G, of which 7720 were eventually manufactured. The sheer number produced is a reflection of just how effective and popular it was in battle.
By comparison to the 11,500 Sturmgeschütze manufactured, only 4,500 Panzer Ills, 6,800 Panzer Ivs and 6,000 Panthers were manufactured in the same period.
While the turreted tanks took on the role of the battlefield rovers, designed to forge ahead of the infantry in wide ranging strategic advances, it was the Sturmgeschütze which accompanied the Grenadiers during the dogged fighting on the ground. As the war dragged on, they became the infantry’s rock in defence and his armoured fist in attack.
By 1943 the Sturmgeschütz was an indispensable part of both the Panzer Division and the ordinary infantry division. The infantry soon came to know that as long as the Gerschutze were in line, things were in control.
Extraordinary results were achieved by skilled crews in Russia, who sometimes accounted for dozens of Russian machines in a single action. In those actions, a major issue for the Sturmgeschütze commanders was the limited fuel and ammunition capacity of their cramped vehicles which produced a constant need to leave the battlefield. As the war progressed, the soldiers in the front line increasingly took strength from the presence of the Geschutze, so the tactical manual for their employment went to great lengths to stress the importance of the Sturmgeschütz commander keeping his infantry commanders informed that his guns were leaving the line only to re-arm and re-fuel.
It was a standard rule of Sturmgeschütz tactical doctrine that, if possible, not all machines would be withdrawn from the line at the same time, but that they should leave the field in relays, otherwise there was a real danger that the morale of the infantry might collapse if they saw their beloved Geschutze withdrawing from the field.
Despite its undoubted success as a tank killer, there was still an infantry support role for the Sturmgeschütz. The low trajectory 75mm gun was an excellent anti-tank gun, but to reach infantry hiding behind obstacles or other terrain features, a high trajectory Howitzer was still required. A further 1,100 Sturmgeschütze were therefore manufactured with the 10.5cm Howitzer which packed a deadly, high explosive punch which could be used in support of the infantry, either in attack or (more usually) desperate defence. The theory was that for every two troops of 75mm armoured Geschutze to deal with enemy tanks, there would be one troop of howitzer-armoured Geschutze to deal with the infantry. Problems with supplies of vehicles meant that this situation was very rarely achieved in practice.
The tactics set down for cooperation between the two types of assault guns was that the guns armed with 7.5cm guns would target any enemy armour, while the howitzer-armoured vehicles would concentrate on the infantry who accompanied the tanks. In this way, countless Russian attacks came to on the bulwark provided by the Sturmgeschütze battalions.
By 1943 the obvious success of the Sturmgeschütz in the field led the allies to target the Alkett factory responsible tor the production of Stug IIIs for priority bombing. The resultant saturation bombing severely damaged the production factories.
During the period of rebuilding production was switched from Alkett to the Krupp’s tank works, but Krupp made Panzer IVs not Panzer IIIs.
During 1943 the 1500 Sturmgeschütze manufactured by Krupp used the Panzer IV tank chassis, combined with the highly successful L/48 gun. These machines, known as Sturmgeschütze IVs, were no less successful than the old Stug IIIs.
By the end of the war over thirty thousand enemy tanks had been destroyed by the Geschutze crews, a ratio of approximately three enemy vehicles to every Stug deployed. It was a mark of the achievement of the guns and the crews that Russian orders forbade their tank commanders from entering into anti-tank duels with the Geschutze head to head, ordering them instead to manoeuvre to find the weaker side and rear armour.
One famous variant of the Stug IV was a real heavyweight, the forerunner of the Sturm Tiger. This was the mighty Brumbar (the grizzly bear, or grumbler), which carried a powerful 15cm Howitzer. The Brumbar had sloping frontal armour 100mm thick and was designed to rumble up to infantry fortifications before firing its massive shell at point blank range.
The Brumbar was originally developed to cope with the close-quarter street fighting at Stalingrad but delays in production meant that they did not see active service until the battle of Kursk in 1943.
After Kursk, Germany was largely fighting a defensive war, but on the few occasions when the Brumbar saw action they acquitted themselves well, and over three hundred were produced by the end of the war.
The eventual production of Sturmgeschütze totalled some 11,500 vehicles, more than any other mark of German fighting vehicle. There were sound reasons for this, as not only was the Sturmgeschütz successful on the battlefield, it was also far less expensive, quicker and easier to manufacture than fully turreted tanks built on the same chassis - a vital consideration for Germany’s hard pressed manufacturing industry. German armies on all fronts were desperate for armoured fighting vehicles to stem the flood of Russian and allied armour, so production resources were increasingly switched to the production of Sturmgeschütze, which were well suited to fighting a defensive war.