Debussy's Late Style explores Claude Debussy's musical responses to World War I. This period of composition encompasses the duration of the war and the last four years of Debussy's life. The works that emerged during this time reflect both wartime events and the composer's self-conscious desire to define his own musical legacy as he felt his life nearing its end. Debussy's complete wartime compositions comprise a small but significant body of works, some little known and some now acknowledged to be among the masterpieces of his career. These include the Berceuse héroïque, En Blanc et noir, the Douze Études, the "Noël des enfants qui n'ont plus de maisons, " and the three instrumental sonatas (the Cello Sonata, the Sonata for Flute, Viola, and Harp, and the Violin Sonata). Through music analysis, musicology, and cultural history, this study offers interpretive readings of Debussy's late works, focusing in particular on how they reflect the unique cultural milieu of wartime Paris.