In 1916 C.E.P. Gourdou and J.A. Leseurre worked on ways of reducing aircraft drag, and eventually encapsulated their findings in a patent filed 9 January 1917, describing a parasol-winged fighter. An order from Aviation Militaire followed, and GL Type a was built by Soc. Wassmer, who normally made propellers. Official testing resulted in demand for stronger wing, resulting in 20 GL 2C1 or Type b, made by Mayen and Zodiac, but order for 100 cancelled at Armistice. Partners decided to continue, and set up at 25 rue Krüger, St Maur les Fossés. First products GL.21 fighter and 22 trainer, Finland buying both (latter as ET). There followed a succession of fighters, trainers, recon aircraft and racers. In 1925 link with Ateliers et Chantiers de la Loire resulted in designations LGL, so new 1925 fighter was LGL.32. This became standard Armée de l'Air type, 479 being built at Loire dockyard, St Nazaire. By 1928 light seaplanes were on test, resulting in long series of shipboard reconnaissance types including one which folded for carriage aboard submarine Surcouf. GL and Loire parted 1929, latter forming its own aircraft department. GL rented 2 hangars at Villacoublay but from 1930 their only landplanes were prototype dive-bombers and a small night fighter.