Officially, the Unimog was never meant to be a military vehicle, in fact, Allied permission to develop the Unimog was granted only because Albert Friedrich, inventor of the Unimog, ensured that the Unimog would not have any military purpose. However, the Unimog has always been a military vehicle. 44 Unimogs of the first model, the Unimog 70200, served as combat engineer tractors in the Swiss army. They proved successful, and the Swiss army purchased 540 units of the 70200's successor, the Unimog 2010. These early Swiss military vehicles were known as ″Dieseli″. The Dieseli-Unimogs remained in service until 1989. Officers of the French army, then occupying forces in Germany, noted the Unimog testing at the Sauberg in the early 1950s and considered the Unimog useful for patrolling purposes. Soon after, the French army purchased Unimogs of the series 2010 and 401. The Unimog proved to be so successful, that Daimler-Benz was ordered to develop an entirely new Unimog just for military purposes. This new model was supposed to be a small 1.5-tonne truck, capable of carrying 10 to 12 soldiers on its bed, at a speed of up to 90 km/h, rather than being an agricultural tractor. Being a NATO member state, France demanded that the military Unimog would have an engine running on petrol. Daimler-Benz decided to use an Otto cycle engine, the M 180, displacing 2.2 litres, and producing 85 PS (63 kW). The military Unimog would later be known as Unimog 404 or Unimog S.