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"
Luftwaffe were meeting large numbers of equal if not superior Allied types. Daytime aerial defense against the USAAF's strongly defended heavy bomber forces, particularly the Eighth Air Force and the Fifteenth Air Force, had its successes through the calendar year of 1943. But at the start of 1944, Eighth AF commander Jimmy Doolittle made a major change in offensive fighter tactics, which defeated the "Luftwaffe"s day fighter force from that time onwards. Steadily increasing numbers of the superlative North American P-51 Mustang single-engine fighter, leading the USAAF's bombers into German airspace defeated first the Bf 110 "Zerstörer" wings, then the Fw