In April 1938 the SS leadership founds the Deutsche Erd- und Steinwerke GmbH (or DESt, German Earth and Stone Works Company) in order to start producing building materials. Concentration camp prisoners are to be exploited as forced labourers. A few months later concentration camp prisoners begin work breaking granite rocks at the Mauthausen Granite Works, the local division of the DESt. The quarries at the Gusen concentration camp also belong to the DESt.
The Gusen quarries are places of forced labour and extermination in equal measure. Prisoners are made to work there for up to 13 hours per day under inhuman conditions. The deliberate wastage of human life is at odds with the economic interests of the SS. While there is a permanent lack of skilled workers in the quarries, countless prisoners are systematically worked to death. Back-breaking penal labour and targeted killing actions are the order of the day.
In 1943 two major arms companies move part of their production to the Mauthausen and Gusen concentration camps: Steyr-Daimler-Puch and Messerschmitt. Thousands of concentration camp prisoners now have to produce weapons and aeroplane parts in Gusen.
Starting in late 1943 several kilometres of tunnels are dug to relocate the arms factories underground. This gruelling work results in high death rates.