The Messerschmitt Bf 109 was a German World War II fighter aircraft designed by Willy Messerschmitt in the early 1930s. It was one of the first true modern fighters of the era, including such features as an all-metal monocoque construction, a closed canopy, and retractable landing gear. Having gone through its baptism of fire in the Spanish Civil War, the Bf 109 was still in service at the dawn of the jet age at the end of World War II, during which it was the backbone of the German Luftwaffe fighter force. An inverted Vee-piston engined fighter, the Bf 109 was supplemented, but never completely replaced in service, by the radial engined Focke-Wulf Fw 190 from the end of 1941.
Originally conceived as an interceptor, later models were developed to fulfill multiple tasks, serving as bomber escort, fighter bomber, day-, night- all-weather fighter, bomber destroyer, ground-attack aircraft, and as reconnaissance aircraft. It was supplied to and operated by several states during World War II, and served with several countries for many years after the war. The Bf 109 was the most produced warplane during World War II, with 30,573 examples built during the war, and the most produced fighter aircraft in history, with a total of 33,984 units produced up to April 1945. The Bf 109 was flown by the three top-scoring German fighter aces of World War II, who claimed 928 victories between them while flying with Jagdgeschwader 52, chiefly on the Eastern Front, as well as by the highest scoring German ace in the North African Campaign. It was also flown by the highest high-scoring non-German ace Ilmari Juutilainen, and several other successful ones, notably from Finland, Romania, Croatia and Hungary. Through constant development, it remained competitive with the latest Allied fighter aircraft until the end of the war.
Spanish Air Force operated some D-1s, E-3s and 15 F-4s, and may have received several older B-types. Volunteers of Escuadrilla Azul on the Eastern Front operated E-4, E-7, E-7/B, F-2, F-4 (belonged in JG-27 under the command of Luftflotte 2,until April 1943) among G-4 and G-6 (detached in JG-51 under the command Luftflotte 4, until June 1944). Between 1939 and 1945, 45 Bf-109Bs, 15 Me-109Es, 10 Me-109Fs and 25 Me-109Gs were delivered to Spain.