By the late 1930s the German military inventory presented an enormous logistic problem, with over 100 different vehicle types in service. A desperate programme to rationalize this situation was put in hand under the leadership of General von Schell, who was then director of mechanization. His aim was to cut down the vast number of types and bring in a degree of standardization which, when plans were finalized, allowed just 30 vehicle types. In the 3-ton medium category Opel's design was the most successful. The Opel Blitz 4x2 was of a conventional layout and featured a pressed steel commercial type cab with wooden body. Under the so called Schell programme all 4x2 vehicles were designated Typ S. The 4x2 was produced in many different variants, for example general service, fuel tankers, house body etc. As the need for better cross-country performance became a premium it was decided by Opel to produce a four-wheel-drive 3-ton truck with the designation Typ A and based on the same basic vehicle design as the Typ S. The addition of a driven front axle gave tremendous advantages over the normal 4x2 truck, and the wheelbase for the 4x4 was shortened by 15cm (5.9m). A two-speed transfer box gave the vehicle a choice of 10 forward gears. During the production span from 1937 to 1944 some 70,000 Opel Blitz trucks were built, as well as over 25,000 Allrad' (four wheel drive) models. By late 1944, however, manufacture was totally disrupted by Allied bombing and the Allied advance across Europe, making plans to produce vehicles in 1945 fruitless
The first winter of the war in the USSR (1941-2) demonstrated to the German army that most of its wheeled transport was completely unable to deal with the dreadful muddy conditions produced during the freeze-thaw weather that marked the beginning and end of the Russian winter. During these conditions it was only the halftracks that could make any headway, but to divert the precious halftracks from their operational purposes to carry out the mundane day-to-day supply functions was obviously uneconomic, so it was decided to produce low-cost halftrack trucks. This was done quite simply by taking Opel and Daimler-Benz trucks from the production lines and removing their rear axles. In their place went new dnveshafts connected to tracked assemblies made from PzKpfw II running wheels and tracks. In itself this was a considerable economic advantage since the PzKpfw II was then going out of production and existing capacity could be retained, making the truck conversion an even more cost-effective venture. The new halftrack trucks were provided with the name Maultier (mule). In the end the conversions used mainly Opel Typ S/SSM trucks, and in service they were generally a success although they tended to lack the overall mobility of the 'proper' halftracks. Not surprisingly, their use was confined to the Eastern Front, and the vehicles were used mainly for routine supply purposes.
It was the Germans who made the best use of the halftrack's capabilities, and not even the massive output of the American arsenals can overshadow the impact that the German halftracks made at the time: even after a period of more than 40 years that impact still remains in the popular imagination. Thus, although the Americans produced more of their halftracks than can be easily appreciated, the main emphasis in this study is on the German halftracks, from the tiny Kettenrad to the mighty SdKfz 9. But one factor must be borne in mind when reading this section; in cost terms, weight for weight the halftrack was, and still is, more expensive than the tank. Production of the SdKfz 9 ceased during 1944, by which time the last versions were powered by the same Maybach engines as those fitted to PzKpfw IV tanks. They were massive vehicles that were certainly impressive to look at, but one has to bear in mind that the basic tractor version cost 60,000 Reichsmarks: a Panther cost 117,100.
The high degree of technology required to make the halftrack reliable is such that each example was an engineering achievement purchased at high cost in time and facilities. If only a small sector of that effort had been diverted to other weapons or equipment things might have been different for the German armed forces.