The Heinkel He 111 was a German aircraft designed by Siegfried and Walter Günter at Heinkel Flugzeugwerke in the early 1930s. It has sometimes been described as a "wolf in sheep's clothing"[3][4] because it masqueraded as a cargo plane though its actual purpose was to provide the nascent Luftwaffe with a fast medium bomber. (Germany had been prohibited by the 1919 Treaty of Versailles from having an air force.) Perhaps the best-recognised German bomber due to the distinctive, extensively glazed "greenhouse" nose of later versions — in effect, a "stepless cockpit", with no separate windscreen panels for the pilot and co-pilot apart from the streamlined shape — the Heinkel He 111 was the most numerous and the primary Luftwaffe bomber during the early stages of World War II. It fared well until the Battle of Britain, when its weak defensive armament, relatively low speed, and poor manoeuvrability were exposed.[4] Nevertheless, it proved capable of sustaining heavy damage and remaining airborne. As the war progressed, the He 111 was used in a variety of roles on every front in the European theatre. It was used as a strategic bomber during the Battle of Britain, a torpedo bomber during the Battle of the Atlantic, and a medium bomber and a transport aircraft on the Western, Eastern, Mediterranean, Middle Eastern, and North African Fronts.