Published: 16/08/2023 | Last Updated on 20/09/2023
The Sturmgeschütz III, commonly known as StuG III, was a German assault gun developed during World War II. Designed primarily for infantry support, it quickly became one of the most successful armored vehicles of the war.
With its low profile and solid firepower, the StuG III proved to be a deadly weapon on the battlefield.
The StuG III was first introduced in 1940 and it remained in production until the end of the war in 1945. It was based on the chassis of the Panzer III tank, but instead of a turret, it featured a fixed gun in a casemate-style superstructure. This design allowed for a lower silhouette, making it less susceptible to being hit by enemy fire.
Armed with a 75mm StuK 40 L/48 gun, the StuG III had excellent anti-tank capabilities. It was capable of penetrating the armor of most Allied tanks at medium range. Additionally, it also served as a highly effective infantry support vehicle, delivering devastating blows to enemy positions.
The StuG III saw action on all fronts during World War II, from the deserts of North Africa to the Eastern Front and the Western Front. Its simplicity, reliability, and firepower made it a valuable asset for the German army, earning it a fearsome reputation among Allied forces.
Now, Tracks of Steel take you on a journey of this amazing weapon! Join us, continue reading!
Development of Stug III Assault Gun
During World War I, German experiences revealed infantry’s inability to effectively engage fortifications on the Western Front. The existing artillery, being heavy and immobile, failed to keep up with advancing infantry and destroy bunkers, pillboxes, and minor fortifications directly.
General Erich von Manstein is credited as the “father” of the Sturmartillerie (assault artillery), proposing its use in direct-fire support for infantry divisions of the German Army. On June 15, 1936, Daimler-Benz AG received an order to develop an armored infantry support vehicle with a 7.5 cm caliber artillery piece mounted on a fixed casemate superstructure. The vehicle’s height was to match that of an average soldier.
Design and Prototypes
Daimler-Benz AG utilized the chassis and running gear of the Panzer III medium tank as a basis for the new Sturmgeschütz. Alkett produced five prototypes in 1937, featuring mild steel superstructures and a 7.5 cm StuK 37 L/24 cannon with a howitzer-like appearance. Production vehicles with this gun were designated “Gepanzerte Selbstfahrlafette für Sturmgeschütz 7.5 cm Kanone Ausführung A bis D (Sd.Kfz.142)”.
The question arose regarding which land combat arm would handle the StuG; it was agreed to integrate it into the artillery arm. StuGs were organized into battalions, later renamed “brigades”, and followed their own doctrine, primarily focusing on infantry support through direct fire and later emphasized anti-tank roles.
Technical details of Sturmgeschütz III
The final vehicle measured 6.77 meters in length, 2.95 meters in width, and 2.16 meters in height, with a weight of 23.9 tons. The range of the “G” variant was 155 km.
For protection for the crew the vehicle’s armor consisted of a 50 mm gun shield, 30 mm turret, 30 mm glacis, 80 mm bow, 30 mm upper hull side, 50 mm upper ear, and 50 mm lower hull rear.
The StuG III’s suspension featured six travel wheels on each side, sprung with torsion bars. The travel wheels had a diameter of 520 mm and were equipped with rubber tires for a smoother ride. The double wheels allowed the tracks’ guide teeth to pass through the gap between them.
To handle the stress during driving, the first and last driving wheels had additional shock absorbers. At the front was a toothed drive wheel with circular relief holes, while the back had a tension wheel. The upper part of the belt was supported by three return rollers with a diameter of 310 mm.
Starting from StuG III Ausf. B, the first return roller was moved slightly forward to reduce the risk of track derailment. To enhance mobility, slightly wider tracks, increased from 380 to 400 mm, were used on the Ausf. B. Additionally, a wide rubber rim was added to the six doubled road wheels to extend their service life. Some vehicles still retained the older type sprockets, showcasing a visual difference.
Engine and transmission
The Stug Ausf.B utilized a modified twelve-cylinder, 12-liter, water-cooled Maybach HL 120 TRM engine, delivering 265 hp at 2,600 rpm. This engine was also used in Panzer IVs, Elefants (2 per vehicle), and Nashorns.
The StuG III Ausf.A featured a complex Maybach Variorex SRG 32 8 145 semi-automatic transmission with ten forward and one reverse speed. While theoretically capable of reaching speeds up to 70 km/h, it proved unreliable with frequent breakdowns. This impractical transmission was quickly replaced with a more straightforward Zahnradfabrik SSG 77 six-speed manual gearbox from the Ausf B model onwards.
Ausf G’s off-road speed reached 20 km/h, while it achieved 40 km/h on-road.
Cost-Effectiveness and Production
Sturmgeschütz vehicles were cheaper and faster to manufacture than contemporary German tanks due to the omission of a turret. A StuG III Ausf G cost 82,500 RM, compared to 103,163 RM for a Pzkpfw III Ausf. M. By the end of the war, around 11,300 StuG IIIs and StuH 42s had been produced overall.
Evolution of the 75 mm Gun of Sturmgeschütz III
Early StuG models were equipped with a low-velocity 7.5 cm StuK 37 L/24 gun, akin to the early Panzer IV versions. However, after the German Army encountering Soviet tanks like the KV-1 and T-34, the StuG received upgrades. It was equipped with a high-velocity 7.5 cm StuK 40 L/43 main gun in spring 1942, followed by the slightly longer 7.5 cm StuK 40 L/48 gun in autumn 1942. These high-velocity guns were identical to those mounted on the Panzer IV for anti-tank purposes but carried less explosive and had a lower blast effect against infantry or field fortifications. These versions were known as the 7.5 cm Sturmgeschütz 40 Ausf.F, Ausf. F/8, and Ausf. G (Sd.Kfz.142/1).
Sight for the Sturmgeschütz III’s Main Gun
The assault guns use two different sights:
StuG III Ausf. A-E versions used Sfl. ZF1 + Rbl. F32 sight, all other StuG III Ausf. F-G: used Sfl. ZF1a + Rbl. F36.
Many StuG III/IV, Hetzer, and Jagdpanzer used this sight/drum combo—a common item. It’s field repairable, containing 3 periscopic lens elements. Swapping a damaged piece was quick, though zeroing might be needed.
Unlike articulated sights in Panzers, the Sfl. ZF1a allowed easy replacement. But if damaged, panzer sights became ineffective for ranged shooting. The Sfl. ZF1a’s roof had a curved slot to move with the gun’s motion.
Starting with the StuG III Ausf. G in December 1942, an added 7.92 mm MG34 machine gun could be mounted on a shield atop the superstructure for anti-infantry protection. Later in the war, some F/8 models were retrofitted with a shield. By 1944, an additional coaxial 7.92 mm MG34 became standard on all production models.
Stug III Variants
In 1937, five StuG III prototypes were produced on Panzer III Ausf. B chassis. By December of the same year, two of these vehicles were in service with Panzer Regiment 1 in Erfurt. These samples featured eight road wheels per side with 360-millimeter (14 in) wide tracks and a 14.5 mm thick soft steel superstructure. They were armed with a 7.5 cm StuK 37 L/24 gun. Although not fit for combat, they served as training vehicles until early 1941.
The StuG III Ausf. A (Sd.Kfz. 142)
The Ausf. A (Sd.Kfz. 142), produced by Daimler-Benz from January to May 1940, saw service during the Battle of France. It featured a modified 5./ZW chassis (Panzerkampfwagen III Ausf. F) with reinforced front armor measuring 5 cm.
The production included 30 vehicles initially, with the last six using chassis diverted from Panzerkampwagen III Ausf. “G” production.
StuG III Ausf. B (Sd.Kfz. 142)
The Sturmgeschütz Ausf. B model featured a modified 7./ZW chassis (Panzer III Ausf. H) with widened tracks (380 mm). The road wheels had two rubber tires, widened from 520 × 79 mm to 520 × 95 mm each, and were interchangeable. The troublesome 10-speed transmission was replaced with a more reliable 6-speed one. To improve track stability, the return rollers were re-positioned further forward, reducing vertical movements before reaching the forward drive sprocket and minimizing track throwing. During production, the original eight-round-hole drive sprocket was replaced with a new cast drive sprocket featuring six pie slice-shaped slots. This new drive wheel accommodated both 380 mm and 360 mm wide tracks. Spacer rings allowed the older sprockets to use 380 mm tracks.
StuG III Ausf. B Sd.Kfz 142 entered production on June 1940, and manufactured to May 1941, with sum of 300 units.
StuG III Ausf. C (Sd.Kfz. 142)
The gunner’s forward view port, which posed a shot trap, was removed and replaced with an opening for the gunner’s periscope on the top. Additionally, the idler wheel was redesigned.
50 units of Ausf. C, Sd.Kfz. 142 maded in April 1941.
StuG III Ausf. D (Sd.Kfz. 142)
Essentially a contract extension of the Ausf. C. It featured an on-board intercom installation and added transmission hatch locks, remaining otherwise identical to the Ausf. C.
150 units of Ausf. D, Sd.Kfz 142 produced in May to September period of 1941.
StuG III Ausf. E (Sd.Kfz 142)
Produced from September 1941 to February 1942, featured extended rectangular proteceted boxes on the sides to accommodate radio equipment. This modification allowed for six additional rounds of ammunition for the main gun, providing a maximum of 50 rounds, along with a machine gun. To protect the vehicle from enemy infantry, one MG 34 and seven drum-type magazines were stored in the right rear side of the fighting compartment. Officially, vehicle commanders were equipped with SF14Z stereoscopic scissor periscopes.
284 “E” models (Sd.Kfz 142) vehicles manufactured in the period of September 1941 to February 1942.