Tank design philosophies in the early inter-war period – Part I: The German concept

After the Armistice of 11 November 1918 the victorious Allies demanded and supervised the effective disbandment of all but a rudimentary and lightly equipped German army. As part of this process the German army’s tank force was disbanded, and the Treaty of Versailles imposed on Germany in June 1919 included among its provisions a total ban on the development of tanks. Yet the German army was already well established in its programme of intelligence-gathering about foreign developments, clandestine evaluation of tank-capable components in Germany, and secret links with countries not unsympathetic to German liaison in the development of their own tank forces. In this last respect the Swedes were the Germans’ most important ‘allies’ in the early 1920s, when the LK II was readied for Swedish production and service as the Strv m/21 under the leadership of Josef Vollmer, designer of the A7V heavy and LK I light tanks of World War I, together with a German army team. As the 1920s progressed the Germans became increasingly involved with the Soviets, both parties thinking that a fair deal had been struck when the Germans were given use of the Kazan tank school as an experimental and proving ground in return for technical information and training provided to the fledgling Soviet tank arm.

Between 1926 and 1929 the Germans readily but secretly broke the strictures of the Treaty of Versailles to produce a number of experimental tanks. These were commissioned in great secrecy from major engineering and arms companies as a means of evaluating trends in the design of armoured fighting vehicles, and also of regaining a manufacturing capability pending the day that Germany would move into the field as a major armoured force.

Hand in hand with this technical and manufacturing effort there was a great volume of theoretical thinking about the operational and tactical employment of armour. By a paradox typical of military history, the Germans were well served by their lack of armour in this period: it left them without the entrenched thinking and existing hardware that inevitably accompanies the existence of in-service weapons, and opened the way for radical though professionally competent thought about the nature and employment of a future tank force. Coupled with a realistic analysis of the German army’s performance in World War I, this paved the way for the development of the Blitzkrieg (lightning war) concept of operations derived ultimately from the thinking of two British theoreticians, Colonel J. F. C. Fuller and, more significantly, Captain B. H. Liddell Hart, toward massive breakthroughs and/or bypassing of the enemy’s major front-line formations and defensive features by massed armour with substantial air support as the first step in fast-moving operations into the enemy’s rear areas.

But while these tactical and operational concepts were still in their embryonic phases the Germans were moving towards the creation of new hardware with the Leichte Traktor VK31 and Grosstraktor, so designated to convey the impression of an agricultural role not contrary to the provisions of the Treaty of Versailles. Limited design work had been undertaken since 1921, but it was 1926 before definitive work was started and 1928 before the first of six Leichte Traktor prototypes (three each from Krupp and Rheinmetall) were delivered for trials at Kazan. The Leichte Traktor was a light tank built of mild steel varying in thickness between 8 and 14 mm (0.315 and 0.55 in), and weighed about 9650 kg (21,274 lb). The type was armed solely with a 37-mm gun in a 360° traverse turret located at the rear of the vehicle, and the front-mounted engine provided a speed of 20 km/h (12.4 mph). In general configuration the Leichte Traktor was reminiscent of the British Medium Tank Mk II, and though an order for 289 was placed this was cancelled in the light of subsequent developments. Details of the Leichte Traktor are lacking, a situation even more pronounced with the Grosstraktor series.

This latter comprised separate designs from Daimler-Benz (Grosstraktor I), Rheinmetall (Grosstraktor II) and Krupp (Grosstraktor III), each designed to the same specification and built to the extent of two mild steel prototypes. Each was of semi-rhomboidal configuration with mud chutes (very large on the Grosstraktor I), weighed about 20000 kg (44,092 lb) and in basic shape resembled the British Medium Tank Mk III. Powered by a 300-hp (224-kW) engine, the tanks were each armed with one 75-mm (2.95-in) gun in the main turret together with three 7.92-mm (0.312-in) machine guns, including one in a subsidiary turret to the rear of the main turret to deter infantry assaults on the tanks’ exposed flanks and rear. The Grosstraktor I is believed to have possessed another subsidiary turret forward of the main gun and to have been amphibious, while the Grosstraktor II was basically similar in overall layout but had less advanced suspension and thus an inferior cross-country performance. Some lessons were learned from the design, construction and evaluation of these types, but even the most cursory assessment convinced the Germans that they were obsolescent in basic concept.

By the time that the various Grosstraktor prototypes had been evaluated, the German army was well advanced with its plans for rearmament and growth, and a new series of tactical tanks was already under development as the planned armoured force’s initial mass-production vehicles. But in common with other such services, the German army still saw the need for a heavy tank, and appreciated the apparent armament advantages of main and subsidiary turrets along the lines of a British type, the A1E1 Independent. This feeling was formalised in a January 1934 meeting to consider a new medium tank: the meeting decided in favour of a fairly large machine with a medium-velocity main gun of large calibre to fire HE shell in support of the more numerous light and medium tank equipped with high-velocity anti-tank guns. The consequent specification produced the six-man Panzerkampfwagen NbFz (Neubaufahrzeuge, or new construction vehicle), which was developed in prototype form as the PzKpfw NbFz A with a Krupp turret and as the PzKpfw NbFz B with a Rheinmetall turret. The Krupp, MAN and Rheinmetall companies undertook design studies for the hull, the successful Rheinmetall type showed some evidence of the concept’s long-toothed pedigree in its retention of a slightly rhomboidal aspect in the high rise to the forward idler and the long downward slope of the upper track run’s rear portion: the definitive hull was based closely on that of the Rheinmetall Grosstraktor II. Construction of all six or eight prototypes was in mild steel varying in thickness from 10 to 70 mm (0.39 to 2.76 in), and the installation of a 500-hp (373-kW) petrol engine provided for good cross-country performance and a maximum speed in the order of 35 km/h (21.75 mph) in combination with a suspension arrangement based on that of VK2001(Rh) prototype for the PzKpfw IV medium tank and consisting of 10 road wheels on each side: these were arranged as five articulated twin-wheel bogies on sprung trailing arms for considerable vertical movement.

The PzKpfw NbFz A concept included a main turret carrying one 105-mm (4.13-in) medium-velocity gun and one 37-mm high-velocity gun in a superimposed co-axial mounting, while the PzKpfw NbFz B was more realistically armed with one 75-mm (2.95-in) KwK L/24 medium-velocity gun and one 37-mm KwK L/45 high-velocity gun in a side-by-side co-axial mounting at the front of an advanced turret with low silhouette and lines that were moderately well sloped for ballistic protection. Both types featured a secondary battery comprising two turrets (identical with that of the PzKpfw I light tank), each armed with two 7.92-mm (0.312-in) machine guns and located to the front right and rear left of the main turret. By the time the prototypes had been delivered the German army had concluded that the day of the multi-turret tank was over, and that in any case such vehicles did not fit well with the new generation of medium tanks in service with or under development for the German army’s new Panzer (armoured) divisions. The vehicles were thus used for trials, and with the designations PzKpfw V (NbFz A) and PzKpfw VI (NbFz B) for propaganda purposes in the Norwegian campaign of April 1940. They were then used for training before being broken up in 1941.

Mention of the NbFz has introduced elements of the Germans’ complex system of military designation, and before proceeding to the main stream of German tank development in the 1930s under the driving leadership of the Nazi government that came to power in January 1933 it is useful to look at this system. Up to the beginning of the Spanish Civil War in 1936, the German designation system for tanks under design, development and construction included, in order of size from smallest to largest, the cover terms LaS (Landwirtschaftlicher Schlepper, or agricultural tractor), Zugführerswagen (platoon/troop commander’s vehicle) and BW (Bataillonsführerswagen, or battalion commander’s vehicle). Experimental vehicles were designated by the letter prefix VK (Vollkettenkraftfahrzeug, or fully tracked motor vehicle) followed by a four-digit suffix in which the first two digits expressed the vehicle’s nominal weight in tonnes, and the last two the prototype number in the sequence: thus the VK1601 was the first prototype in the 16-tonne fully-tracked class. This VK system was often completed by a bracketed letter indicating the manufacturer. Once the vehicle had been accepted for service, it was allocated a service designation based on the abbreviation PzKpfw (Panzer Kampfwagen, or armoured vehicle) followed by a roman number, and when it entered service it was also given an ordnance list designation based on the abbreviation SdKfz (Sonder Kraftfahrzeug, or particular vehicle) followed by an Arabic number. Variants of the basic machine were indicated in the cover name system by an Arabic numeral prefixed to the name by an oblique stroke, in the PzKpfw system by the abbreviation Ausf (Ausführung, or model) followed by a letter or alphanumeric combination, and less commonly in the SdKfz system (to indicate a major variation) by an Arabic number separated from the main designation by an oblique stroke.

It is also worth noting that German gun calibres are properly quoted in centimetres, but are here translated into millimetres to facilitate comparison with the tank guns of other countries. German tank guns were generally designed in the KwK series, the abbreviation standing for Kampfwagen Kanone (fighting vehicle gun) and being followed by a two-digit number to denote year of acceptance, or by an L/-type indication of bore length in calibres.

The German army began to plan its overt growth to world capability in 1932, and an accelerating implementation and indeed augmentation of this plan followed the Nazis’ rise to power. Plans had already been laid for the development of a tank force based on existing prototypes, but the recommendations of men such as Oberst Heinz Guderian for a massive force of comparatively light armour used in the Blitzkrieg concept of fast-moving operations found favour with the army’s political masters, who saw both military and propaganda value in a multitude of smaller vehicles that could be obtained for the same financial and industrial outlay as a considerably smaller number of heavier vehicles. In 1933, therefore, the German army started to plan a family of tactically inter-related armoured fighting vehicles for development over the next few years.

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