In response to a request from the Ministry of Defence — which sought a reliable, lightweight vehicle with good towing and off-road capability, built primarily from non-strategic materials — Steyr proposed a tracked vehicle based on the Steyr 1500A light truck. It retained the mechanical components but featured a newly designed enclosed cab made from stamped steel and was powered by the same 3.5-litre petrol V8 Steyr engine, delivering 85 hp.
Contrary to common practice in German half-tracked vehicles, the wheels supporting the metal tracks were aligned rather than interleaved. This design choice, informed by frontline experience, prevented the build-up of mud and ice between the wheels — a frequent issue on the Eastern Front, where extreme cold often led to track immobilisation in vehicles such as the widely used Sd.Kfz. 7, 11, and 251.
With excellent off-road performance, the RSO/01 (short for Steyr Raupenschlepper Ost/01) was employed as an artillery tractor, typically towing pieces such as the 7.5 cm PAK 40 (Panzerabwehrkanone 40) or the 10.5 cm leFH 18 (leichte Feldhaubitze 18). However, its versatility and reliability soon saw it used in a wide range of transport and cargo roles.
Nonetheless, it was not without drawbacks. Its maximum speed of just 30 km/h meant the RSO/01 was confined to infantry units — primarily horse-drawn formations — and unable to keep pace with motorised divisions. While reliable, the engine was also very noisy and could be heard from a distance, and the cab offered no armour protection whatsoever for its occupants.
Between 1942 and 1945, over 25,000 examples were built by Steyr, Wanderer, Magirus, and Gräf & Stift. From 1944 onwards, production shifted to the simplified RSO/02 variant, featuring a soft-top canvas roof and angular cab design, partially made of wood. By late 1944, Magirus began building the RSO/03, in which the Steyr V8 was replaced by a four-cylinder, 5.3-litre Deutz diesel engine — reducing top speed to just 22 km/h, yet still significantly faster and more efficient than the horse-drawn carts it often accompanied.
After the war, Magirus built around 1,500 Waldschlepper RS 1500, a civilian half-track designed for forestry use, which incorporated surplus parts from the RSO programme.