The Sturmgeschütz III (StuG III) was an assault gun produced by Germany during World War II. It was the most-produced German fully tracked armoured fighting vehicle, and second-most produced German armored combat vehicle of any type after the Sd.Kfz. 251 half-track. It was built on a slightly modified Panzer III chassis, replacing the turret with an armored, fixed superstructure mounting a more powerful gun. Initially intended as a mobile assault gun for direct-fire support for infantry, the StuG III was continually modified, and much like the later Jagdpanzer vehicles, was employed as a tank destroyer.
Development The originated from German experiences in World War I, when it was discovered that, during the offensives on the Western Front, infantry lacked the means to engage fortifications. Their MG-08 machine guns and Minenwerfers were too heavy to accompany German assault troops for long periods of time, much less field artillery. The German army adopted by modifying field guns, like captured Russian 76.2 mm pieces, into makeshift infantry guns (). The infantry guns were attached to infantry regiments and provided responsive immediate fire support against fortified machine guns positions. By the end of the war, the Imperial German army had developed the purpose built 7.5 cm 18, or 7.5 cm le.IG 18.Gudmundsson, pp. 119–121
The interwar German army kept the 7.5 cm le.IG 18 and later added the 15cm schweres Infanteriegeschütz 33 (sIG 33) infantry gun to the regimental cannon companies. The heavy firepower came at the cost of a gun that required horses to move. As a consequence, the sIG was not suitable for an accompanying gun supporting the infantry attack. The 7.5cm infantry gun provided decent firepower but was still heavy to move.
Erich von Manstein is considered the father of the (assault artillery). He had served as an infantrymen in World War I and so was intimately familiar with the requirement for immediate fire support for infantry assaults. In the interwar period (Colonel) Manstein served as the chief of the operations section of the German General Staff - a position that he used to advocate for what became known as assault guns (). Unlike self-propelled guns, where the vehicle is used as a means of movement, Manstein envisioned the as an armoured fighting vehicle providing mobile direct fire support to infantry commanders. He also envisioned the vehicles as controlled by the artillery branch, not armor or the infantry. Manstein's proposal was to attach an assault gun battalion () of three batteries of six guns to each infantry division - thus giving the division commander responsive fire support at the (decisive point) of the operation. The proposal was approved by Werner von Fritsch, the commander in chief, to develop a new assault gun.Zaloga 2013, pp. 12–13
Soon thereafter, the assault gun concept ran into stiff resistance, most notably from Heinz Guderian, an advocate of building up the strength of the panzer arm, and he saw the StuG III diverting scarce resources away from the Panzer Mark III tanks. Guderian failed to stop the StuG III plan but succeeded in reducing Manstein's battery per infantry division. The new battalions would be held at the field army level.
On 15 June 1936, Daimler-Benz AG received an order to develop an armoured infantry support vehicle capable of mounting a caliber gun. The gun mount's fixed, fully integrated casemate superstructure allowed a limited traverse of 20° and provided overhead protection for the crew. The height of the vehicle was not to exceed that of the average soldier.
Daimler-Benz AG used the chassis and running gear of its recent Panzer III medium tank as the basis for the new vehicle. Prototype manufacture was passed over to Alkett, who produced five prototypes in 1937 on a Panzer III B (Ausf. B) chassis. These prototypes had a mild steel superstructure and a Krupp short-barrelled 7.5 cm StuK 37 L/24 gun. Production vehicles with this gun were known as A D (Sd.Kfz.142).
As the StuG was designed for infantry close support, early models mounted a howitzer-pattern, 7.5 cm StuK 37 L/24 gun, similar to gun mounted in early versions of the turreted Panzer IV. The StuK L/24 gun was designed primarily to fire high explosive shells to destroy hostile enemy heavy weapons. The gun could also fire armor piercing shells but in a secondary role. The manufacture and fielding of the StuG III was such a low priority that only four batteries took part in the Battle of France in May-June 1940. The StuG III proved effective in close support by filling the gap between the horse drawn artillery of the infantry divisions and the infantry regiments. The Germans also found the motorized artillery in the panzer divisions were less effective in rapid movement than the fully mechanized Stug III batteries. Lastly, the purpose built StuG III performed better than the poorly engineered 15cm sIG Ausf B. - an assault gun created by mounting the 15cm sIG infantry gun on an otherwise obsolete Panzer Mk I chassis. StuG III production was increased in the months leading up to Operation Operation Barbarossa. By June 1941 the had eleven StuG III and five batteries, totalling 339 machines, that would support the invasion of the Soviet Union. Most of these vehicles were the Alkett-manufactured StuG Ausf. B, which had an improved transmission and steering gear.
The early StuG III performed well during the Battle of France but C and D incorporated further changes: improved road wheels, oil bath air cleaners, improved front armor, and a new sight aperture to eliminate a shot trap. The original sight was replaced by an artillery scissors periscope. These marks of vehicles were made by Alkett from May to September 1941. E, produced from September 1941to February 1942 featured a wider casemate with room for radio equipment. All these early marks were powered by the same Maybach HL 120 TRM gasoline engine and armed with the 7.5cm StuK L/24.
After the Germans encountered the Soviet KV-1 heavy and T-34 medium tanks, a III E was modified with a high-velocity 7.5 cm StuK 40 L/43 main gun. 120 of the vehicle, designated F, were made by Alkett before the longer barreled more capable 7.5 cm StuK 40 L/48 was installed and used for the remainder of the F. The III F/8 begin appearing in September 1942, which incorporated changes made concurrently to the PzKpfw III 8./Z.W. Changes included the adding of towing brackets to the frontal armor, supplemental 50 mm rear armor and improvements to track guards and engine louvers. Later vehicles in this production run featured bolted 30 mm supplemental front armor, redesigned hatches, and a prototype hinged machine gun shield for the loader's hatch. The final variant, the III Ausf. G entered production in December 1942. Demand for the vehicles was so high that Alkett, (Miag), (MAN), were involved. The chassis, main gun and engine remained the same as the F/8, while the casemate received significant changes. A commander's cupola with periscopes was added on top of a raised roof, while the sides were sloped to increase resistance to shot. The Ausf. G remained in production until the end of the war, and received many smaller engineering changes, which included a cast mantlet, improved driver's ports, and adding a coaxial machine gun. Total production for this variant ran over 7,800 vehicles.
Alkett also experimented with mounting a 105 mm leFH 18 howitzer into an adapted III . E, that proved successful and Alkett ultimately manufactured about 1,300 G by the end of the war. The 10.5 cm howitzer fired a larger high explosive shell with double the charge of the comparable 7.5cm shell, thus was well suited for reducing fortified positions. When Alkett's plant was hit by Allied bombs in late 1943, the Germans adapted by mating the StuG III superstructure to the hull of a Panzer IV Ausf. H. The hybrid vehicle proved successful and was named the . Production of this armored fighting vehicle ran concurrently with the III and both remained in production to the end of the war.
Operational history
German army As noted above, the four batteries of StuG III to participate in the Battle of France proved their worth to the Heer leadership. Additional batteries, and detachments consisting of three batteries each, were activated in the fall and winter of 1940. Two StuG III battalions supported the Balkans Campaign (World War II) and eleven StuG II Abteilungen and five batteries took part in the 1941 invasion of the Soviet Union. Most early marks of the StuG III were earmarked for Operation Barbarossa, leaving few of the assault guns for other theaters. For example, General Erwin Rommel's Afrika Korps received only a single detachment of StuG III Ausf. D in early 1942. Rommel was instead given a variety of self-propelled guns pieced together from existing components --like the 15cm sIG 33 auf Fahrgestell Panzerkampwagen II (Sf)--or from mating a German artillery piece to a French tank chassis.
The wastage on the Eastern Front and demands on German heavy industry meant the losses of 1941 were not corrected until mid-1942. The Germans had about 210 StuG III (of all Ausf.) in eighteen battalions for the start of Operation Blau. The Heer continued to add StuG III battalions and by mid-November 1942 had roughly 442 of the armored fighting vehicles in twenty battalions.
Waffen-SS units [PLACEHOLDER]
Other armies As the war on the Eastern Front shifted to the Allies, the Finnish Army faced the possibility of defending against the Red Army again, after the Winter War. The Finnish Army received approval from Adolf Hitler to receive forty-five StuG III Ausf. G to form an assault gun battalion for their sole armored division. The assault gun battalion was organized in February 1943, but its cadre did not reach Germany for training until June 1943. Over a five week course, half the Finnish students learned to operate the StuG III, while the remainder learned to maintain and repair the vehicle. The first cadre returned to Finland in August 1943 to begin training the remainder of the battalion - which included several officers who had served with Finnish Waffen-SS units previously. The assault gun battalion was operational by the fall of the 1943, with 22 assault guns in three firing companies - and the remaining 8 StuG III held in depot level reserve. The Finnish Tank Centre performed several modifications: removing the Schurzen, adding wooden storage chests on the rear hull, substituting Red Army/Finnish small arms weapons for the German MG42 and MP40s, and repainting in the Finnish army camouflage scheme. During the defense of Kuuterselkä on the Karelian Isthmus in August 1944, the Finnish assault battalion claimed the following kills: T-34 (all types), 65; ISU-152, 13; KV-1, 5; all others 4. By contrast, the Finns lost five StuG III. Finnish crews referred to the Stug III by an early German designation, Stu. 40 or more commonly "Sturmi."
One hundred StuG III Ausf. Gs were delivered to Romania in the autumn of 1943. They were officially known as TAs (or TAs T3 to avoid confusion with TAs T4 (Jagdpanzer IVs)) in their army's inventory. By February 1945, 13 were still in use with the 2nd Armoured Regiment. None of this initial batch survived the war.Scafes and Serbanescu 2005, p.77 Thirty-one TAs were on the Romanian military's inventory in November 1947. Most of them were probably StuG III Ausf. Gs and a small number of Panzer IV/70 (V) (same as TAs T4). These TAs were supplied by the Red Army or were damaged units repaired by the Romanian Army.Scafes and Serbanescu 2005, p.47 All German equipment was removed from service in 1950 and finally scrapped four years later due to the army's decision to use only Soviet armour.