From January 1918 to January 1921 Poulenc was a conscript in the French army in the last months of the First World War and the immediate post-war period. Between July and October 1918 he served at the Franco-German front, after which he was given a series of auxiliary posts, ending as a typist at the Ministry of Aviation. His duties allowed him time for composition; the "Trois mouvements perpétuels" for piano and the Sonata for Piano Duet were written at the piano of the local elementary school at Saint-Martin-sur-le-Pré, and he completed his first song cycle, "Le bestiaire", setting poems by Apollinaire. The sonata did not create a deep public impression, but the song cycle made the composer's name known in France, and the "Trois mouvements perpétuels" rapidly became an international success. The exigencies of music-making in wartime taught Poulenc much about writing for whatever instruments were available; then, and later, some of his works were for unusual combinations of players.