Gustave Delage, the Nieuport company’s chief designer, undertook various progressive developments of his basic sesquiplane concept. The Nieuport 17 was virtually a new design, not a Bébé derivative, the wing area being increased and fitted with neat fairings on the fuselage behind the engine cowling. The first examples began appearing in April 1916 and were to be widely used by French, British, Belgian, Italian and Russian units. Normally armed with a synchronised Vickers machine gun mounted ahead of the pilot, some examples carried over-wing Lewis guns – others carried two guns to increase their firepower. The Nieuport 17 became the mount of many top-scoring Allied airmen and enjoyed comparatively lengthy service until being gradually phased out with the advent of superior Allied types such as the SPAD XIII and Sopwith Camel.