The Bf 109 first saw operational service in 1937 during the Spanish Civil War and was still in service at the dawn of the jet age at the end of World War II in 1945. It was one of the most advanced fighters when it first appeared, with an all-metal monocoque construction, a closed canopy, and retractable landing gear. It was powered by a liquid-cooled, inverted-V12 aero engine. It was called the Me 109 by Allied aircrew and some German aces, even though this was not the official German designation. Originally the aircraft was designated as Bf 109 by the RLM, since the design was submitted by the Bayerische Flugzeugwerke (literally "Bavarian Aircraft Works", meaning "Bavarian Aircraft Factory"; sometimes abbreviated B.F.W. It was conceived as an interceptor, although later models were developed to fulfill multiple tasks, serving as bomber escort, fighter-bomber, day-, night-, all-weather fighter, ground-attack aircraft, and reconnaissance aircraft. It was supplied to several states during World War II, and served with several countries for many years after the war. The Bf 109 is the most produced fighter aircraft in history, with a total of 33,984 airframes produced from 1936 to April 1945. For extensive details of the development, design, operational history and variants, click here. Specifications below are for the Bf 109G6 model.