From 1943, the camp was an important center of armaments production for Messerschmitt and Steyr-Daimler-Puch. In order to expand armaments production, the camp was redesignated Gusen I, and additional camps, Gusen II and Gusen III, were built. Prisoners were forced to construct vast underground factories, the main one being the Bergkristall [de; es], intended for the production of Messerschmitt 262 jet fighter aircraft.