StuG III was without any doubt one of the most famous German self-propelled gun of the Second World War. It made its entry in 1936 when Heereswaffenprüfamt (Direction of the armament of the Army) accepts a request of the Inspection of the infantry which wished the creation of a self-propelled gun of support. Daimler-Benz was invited to establish the plans while being useful of the chassis of Panzer III as bases for this new armoured vehicle. The production of the superstructure and the armament was entrusted to Krupp. The chassis used for the prototypes (O-series) was that of Pz.Kpfw III Ausf.B. These machines were recognizable with the access doors present on the nose of the hull. 5 prototypes of this series were manufactured. This chassis was covered with a lowered enveloping armoured superstructure (bolted) in place of the turret which gave to the vehicle a low silhouette (what was required). The selected armament was the 75mm KwK 37 L/24 already assembled on Panzer IV, at low initial speed (conceived for a role of fire support). The gun of 75mm did not have that a limited traverse of 12° on each side. No protection anti-glares was provided in the beginning, which could be very dangerous when the gun was in maximum elevation. Only a canvas cover surrounded the mounting to protect the crew against the bad weather. The shielding was of 50mm in front and of 10mm elsewhere.

Specimen belonging to the "O-series" including 5 prototypes.

src: site "Germany's Vehicle history"

With the origin the machine was called Selbstfährlafette für Sturmgeschütz 75mm KwK (mounting armoured for assault gun of 75mm) but will be called thereafter simply Sturmgeschütz III or StuG III. The first model of production, based on Pz.Kpfw III Ausf.F, product with 30 specimens by Alkett, accepted the designation of Sturmgeschütz III Ausf.A (Sd.Kfz 142). These machines will be manufactured between January 1940 and Mai 1940. The first delivered will take part in the beginning of the campaign of France within 4 batteries.

Sturmgeschütz III Ausf.A (75mm KwK L/24) during the campaign of France in 1940.

src: site "Panzer Page von Reitsch"

The V-12 engine (gasoline) Maybach HL 120TR and the gear box Variorex (10 foreward speeds and 1 reverse speed) gave it performances identical to Panzer III. The weight of combat was of 19600kg and the crew was composed of 4 men placed in the compartment of combat. The interior space of the compartment of combat made it possible to transport 44 rounds of 75mm. The vehicle was divided into two compartments, that of combat accomodating all the crew, as well as the pilot and the engine compartment. The access to the compartment of combat was done via the 3 trap doors present on the roof. The trap doors of inspection on the glacis could be used as escape exit to the pilot so necessary. The pilot had sat in the front-left corner in front of the gunner. The commander had sat in the back-left corner and the radio-loader in the back-right corner. A hole at the bottom of a depression (V-shape) on the front part of the superstructure made it possible to the gunner to use its sight tube, Rblf32. This depression was striated to prevent the glares to reach the opening. The large defects of this first model was the vulnerability of optics and the lack of machine-gun for brought closer defense. The suspension is identical to that of Pz.Kpfw III Ausf.F with the tracks of 360mm. The shielding was of 50mm in front and 30mm elsewhere.