The Luftwaffe was the aerial warfare branch of the German Wehrmacht during World War II. After the German Empire's World War I-era army air force, the Luftstreitkräfte, and the Kaiserliche Marine naval air units had been disbanded by May 1920 under the terms of the Treaty of Versailles, the Luftwaffe was reformed on 26 February 1935 and grew to become one of the strongest, most doctrinally advanced, and most battle-experienced air forces in the world when World War II started in Europe in September 1939. After the defeat of the Third Reich, the Luftwaffe was disbanded in 1946.Luftwaffe is also the generic term in German speaking countries for any national military aviation service, and the names of air forces in other countries are usually translated into German as "Luftwaffe" (e.g. Royal Air Force is often translated as "britische Luftwaffe").[citation needed] However, Luftstreitkräfte, or "air armed force", is also sometimes used as a translation of "air force" for post-World War I air arms, as it was used as the first word of the official German name of the former East German Air Force, disbanded the day before German reunification was achieved in October 1990. Since "Luft" translates into English as "air", and "Waffe" may be translated into English as either "weapon" or "arm", "Air Arm" may be considered the most literal English translation of Luftwaffe (cf. Fleet Air Arm).[citation needed]One of the forerunners of the Luftwaffe, the Imperial German Army Air Service, was founded in 1910. After the defeat of Germany in WW I, the service was dissolved in 1920 under the conditions of the Treaty of Versailles. During the interwar period, German pilots trained in violation of the treaty in secret. By the summer of 1939, the Luftwaffe had nine Jagdgeschwader (fighter wings) mostly equipped with the Messerschmitt Bf 109E, four 'Zerstörergeschwader (destroyer wings) equipped with the Messerschmitt Bf 110 heavy fighter, 11 Kampfgeschwader (bomber wings) equipped with mainly the Heinkel He 111 and the Dornier Do 17Z and four Sturzkampfgeschwader (dive bomber wings). The Luftwaffe '​s Condor Legion experimented with new doctrine and aircraft during the Spanish Civil War. Throughout the history of the Third Reich, the Luftwaffe had only two commanders-in-chief. The first was Hermann Göring, with the second and last being Generalfeldmarschall Robert Ritter von Greim.When the Second World War began, the Luftwaffe was one of the most technologically advanced air forces in the world. From the start of the war till its end, it was engaged in war crimes and atrocities, starting with strafing civilian refugees to human experiments. In the summer of 1940, the Luftwaffe contributed to the unexpected success in the Battle of France. During the Battle of Britain, the Luftwaffe, despite causing severe damage to the Royal Air Force's infrastructure and British cities during the subsequent Blitz, did not achieve air superiority. The Defence of the Reich campaign gradually destroyed the Luftwaffe's fighter arm. Despite its belated use of advanced turbojet and rocket propelled aircraft for bomber destroyer duties, it was overwhelmed by Allied numbers and a lack of trained pilots and fuel. A last-ditch attempt, known as Operation Bodenplatte, to win air superiority in January 1945 failed. After the Bodenplatte effort, the Luftwaffe had ceased to be an effective fighting force.