Detach two before flight. The Messerschmitt Bf 109, sometimes incorrectly called the Me 109 (most often by Allied pilots and aircrew), is a German World War II fighter aircraft designed by Willy Messerschmitt and Robert Lusser during the early to mid-1930s.[2] The "Bf 109" designation was issued by the German ministry of aviation and represents the developing company Bayerische Flugzeugwerke (at which the engineer Messerschmitt led the development of the plane) and a rather arbitrary figure. It was one of the first truly modern fighters of the era, including such features as all-metal monocoque construction, a closed canopy, and retractable landing gear. It was powered by a liquid-cooled, inverted-V12 aero engine.[2]The Bf 109 first saw operational service during the Spanish Civil War and was still in service at the dawn of the jet age at the end of World War II, during which time it was the backbone of the Luftwaffe's fighter force.[3] From the end of 1941, the Bf 109 was steadily being supplemented by the superior Focke-Wulf Fw 190.