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"
Jagdgeschwader 52 designed a Luftwaffe of 2,370 active planes by April 1938, which would require the production of about 18,000 planes to cover attrition. When 1938 came, the Luftwaffe split its fighter groups into light "Jagdgeschwader" flying the Messerschmitt Bf 109, for home defense, and heavy fighter wings called "Zerstörergeschwader" flying the Messerschmitt Bf 110, for offensive operations, based on doctrine devised over the 1930s. Although the Luftwaffe simply could not meet its mandated pre-Munich Agreement size, five times its then current size, aircraft poured into the various "Geschwader" around the country. At the Ingolstadt-Manching base, north of Munich, I./JG 433 was