The Albatros C.I, (post-war company designations L.6 & L.7), was the first of the successful C-series of two-seat general-purpose biplanes built by Albatros Flugzeugwerke during World War I. Based on the unarmed Albatros B.II, the C.I reversed the pilot and observer seating so that the observer occupied the rear cockpit which was fitted with a ring-mounted 7.92 mm (0.312 in) Parabellum MG14 machine gun. Design and development In late 1914, the German Luftstreitkräfte, the air service of the Imperial German Army, developed a requirement for two-seat aircraft, the C-type, powered by engines of at least and armed with at least one machine gun. The Albatros Flugzeugwerke's design to meet this requirement, the Albatros C.I, was designed by Robert Thelen as a development of Albatros' unarmed B.II biplane. It differed from the B.II by having a more powerful engine, while the pilot was moved to the front cockpit, with the observer in the rear cockpit being provided with a flexibly mounted machine gun, usually a Parabellum MG 14, but sometimes the less satisfactory Bergmann MG 15. It was powered by a Benz Bz.III or a Mercedes D.III engine, both water-cooled six-cylinder inline engines depending on availability. Aircraft used by the Imperial German Navy used the Rapp Rp III engine as they were denied access to the preferred Benz or Mercedes engines. Most aircraft were fitted with radiators attached to the side of the fuselage, but later aircraft replaced these with a radiator fitted to the centre-section leading edge of the upper wing. About 485 C.Is were ordered from Albatros in 1915, with a further 88 C.Is ordered from Luft-Fahrzeug-Gesellschaft (which used the trade name Roland for its aircraft), while 56 C.Is were ordered from Albatros' Austro-Hungarian subsidiary Ostdeutsche Albatros Werke (OAW) for the Austro-Hungarian Aviation Troops. In 1917, in response to a growing demands for training its aircrew, the Luftstreitkräfte placed a series of very large orders for trainer aircraft, including the C.I. The Bayerische Flugzeug-Werke (BFW) built the C.Ia, designed to be powered by the Argus As III, while the C.Ib, powered by a Mercedes D.III, was built by Mercur Flugzeugbau. In August 1918, Albatros and Mercur received orders for a new trainer version, the C.If, with pneumatic springs replacing the rubber shock cords used in the aircraft's undercarriage owing to shortages of raw materials, although it unclear how many, if any, C.Ifs were completed. Improvements to the C.I resulted