According to Yad Vashem historian Daniel Uziel, the conversion of Flossenbürg to armaments production was especially significant because it had been the most profitable DEST enterprise. The number of prisoners working for Messerschmitt increased greatly after the bombing of Messerschmitt's Regensburg plant on 17 August 1943. That month, 800 prisoners worked for Messerschmitt; a year later, 5,700 prisoners were employed in armaments production. , a subcontractor of Messerschmitt, established Flossenbürg subcamps to support its production: a subcamp at Johanngeorgenstadt, established in December 1943, to produce tailplanes for the Bf 109, and another subcamp at Mülsen-St. Micheln which produced aircraft wings, in January 1944. Despite strict regulations forbidding contact, the German civilian workers came into contact with prisoners and some helped by providing extra food or other assistance.