Between 21st April 1944 and 15th April 1945 a concentration camp operated on the grounds of the pioneer barracks of Melk. With approximately 14.390 prisoners who were forced to work here in the course of one year it was one of the biggest satellite camps of Mauthausen concentration camp and the biggest satellite camp in Lower Austria.

The camp prisoners came from more than 20 countries and their work consisted primarily of digging an underground tunnel complex in the Wachberg hill which is situated between Melk and Loosdorf. In the tunnels created by the camp prisoners the Steyr-Daimler-Puch Company produced war material (mainly ball bearings) as of late fall of 1944.