WesWorld

Development of the Panzers, 1937

As word of the Japanese Type 96 and it's long 75mm gun reached Germany, a decision was made to uparmor the Panzer III and IV (as an interim measure, no larger tank guns were available) and to investigate improvements in the Panzer II for the light tank and reconnaissance roles.

Uparmoring the Panzer III and IV proved to be easy: the chassis and suspension had been built with sufficient growth room in mind that the process was quite easy, the only noticeable change to the crews was an increase in ground pressure and hence an exacerbated tendency towards bogging down in soft ground. 20mm armor plates were bolted and welded onto the front and upper sides of the hull and onto the front, sides, and rear of the turrets, and strengthened torsion bars were installed for the front 3 road wheels. This brought the panzer's weight up to just under 24 metric tons. These models were referred to as the Panzer IIIE and the Panzer IVD.

The Panzer II was upgraded by installing an improved version of it's existing engine, giving 200 horsepower versus the earlier versions 160, making the panzer faster by almost 10.5 km/h. Proposals for replacing the current 20mm cannon with a 30mm cannon were left on the drawing boards for now, since there were no currently available 30mm cannon (Rheinmetall was working on one for the Luftwaffe, but it wasn't ready yet).

A single Sturminfanteriegeshutz 33B prototype, based on the Panzer III chassis was built and demonstrated late in the year as a means of giving mobility and protection to the 150mm infantry gun. No decision was made on production in 1937, though the general review of the vehicle was favorable.

The Panzer II chassis was also examined for it's growth potential, given that the larger Panzer III/IV chassis was expected to be produced at it's best rate for the near future. The Panzer II, on the other hand, would not be needed in as large a quantity in it's current form, giving the potential for reuse of the production line if the chassis could be, with minor modifications, be used for other purposes (like the imperfect but already demonstrated 10.5 cm howitzer on the chassis).

By the middle of the year, the designers had come up with a stretched chassis (4.8 m vs 4.5 m in length) with a strengthened suspension and a gap between the 2nd and 3rd road wheel, in two variants, one with the engine in the rear as in the Panzer II and another with the engine in the middle of the vehicle. The second variant was intended as a chassis for an improved self-propelled 10.5cm howitzer for indirect fire with a lightly armored superstructure, while the first was intended for an enlarged light tank or light assault gun. The first prototypes produced in late 1937 were a self-propelled 10.5cm howitzer and a sturmgeschutz armed with a direct-fire 7.5cm howitzer identical to the howitzer installed on the Panzer IVC & D.

The Panzer II chassis was extended to 5.4 meters for the Belgian light tank competition, giving additional room for a larger 240 hp diesel engine and the desired 47mm FRC gun, ammunition, and radio fit. Currently, this longer chassis is not seen as required by the Heer, but that belief may change if the Heer finds the 4.8m chassis cramped for the support vehicle designs (self-propelled howitzer, assault gun, possible future AA vehicle) it is looking at on the Panzer II chassis. All three chassis (4.5, 4.8, & 5.4m) are available for export to foreign customers.

[The 5.4m chassis can be recognized by an observer easily as there is a 5th road wheel on each side to support the extra length and weight of the vehicle. The 4.8m chassis does not have the additional road wheel, but it does have a distinct gap between the 2nd and 3rd road wheels which the 4.5m chassis does not have.]

The Sturmgeshutz III was always the ignored step-child of German panzer production during the mid-1930s: of the three vehicles on the common Panzer III chassis, it was the lowest in priority for production. By the middle of 1937, only 133 had been produced, and that included 48 A models that were merely test/training models, built out of mild steel instead of armor plate. The limits of tank production capacity meant that producing more vehicles would require either the building of a new production line or the conversion of the Panzer II production, both of which had costs the Heer's budget would not allow. Thus the Heer was rather interested when the Sturmgeshutz II was first proposed and then built for Argentina: it offered a way out of the production bottleneck that would not interfere with continuing production of the Panzer III/IV series tanks.

The Sturmgeshutz II showed no particular vices in it's trials other than being a bit tighter inside than the larger vehicle. The Heer thought the larger engine used by the Argentine vehicle unnecessary for an infantry support vehicle, but it was used in the Argentine vehicles for reasons of compatibility with the light tanks on the same chassis.

All in all, it should be counted as no surprise that the Heer decided, as 1937 came to a close, to switch it's remaining orders for Stug IIIs to orders for a German version of the Stug II. Initially the two vehicles would be used interchangeably,, but over time, as the production of Stug IIs caught up with the Heer's needs for sturmgeshutz, the StuG IIIs currently in service would probably be sent to Alkett for conversion to SIG 33Bs. THAT role, of heavy assault gun, the smaller Panzer II chassis could not reasonably handle, while the larger Panzer III chassis could do so easily enough.