Messerschmitt Bf 109 11 July 1938 when Erhard Milch finally allowed Willy Messerschmitt to acquire the company. All Messerschmitt aircraft that originated after that date, such as the Me 210, were to carry the "Me" designation. Despite regulations by the RLM, wartime documents from Messerschmitt AG, RLM and "Luftwaffe" loss and strength reports continued to use both designations, sometimes even on the same page. All extant airframes bear the official "Bf 109" designation on their identification plates, including the final K-4 models. The aircraft was often referred to by the folk-designation, 'Me 109', particularly by the Allies. The aircraft was often nicknamed "Messer"
Messerschmitt Bf 109 August 1939. In January 1943, as part of an effort to increase fighter production, Messerschmitt licensed an SS-owned company, DEST, to manufacture Bf 109 parts at Flossenbürg concentration camp using the expertise of Messerschmitt engineers and the labor of inmates. Because the prisoners were not paid, the enterprise was highly profitable for both Messerschmitt and the SS. After a USAAF bombing raid damaged the Messerschmitt factory at Regensburg in August 1943, some Bf 109 production was relocated to Gusen in Austria, the most brutal Nazi labor camp. Aircraft parts were manufactured by prisoners, whose average life expectancy was six months.