Debussy was an ardent nationalist who sought to purge all German (especially Wagnerian) stylistic features from his music. He claimed that he wanted his music to express his French identity. Much of his music, however, is saturated with markers of exoticism. My dissertation explores the relationship between his interest in musical exoticism and his anti-Wagnerian nationalism. I argue that he used exotic markers as a nationalistic reaction against Wagner. He perceived these markers as symbols of French identity. By the time that he started writing exotic music, in the 1890's, exoticism was a deeply entrenched tradition in French musical culture. Many 19th-century French composers, including Felicien David, Bizet, Massenet, and Saint-Saëns, founded this tradition of musical exoticism and established a lexicon of exotic markers, such as modality, static harmonies, descending chromatic lines and pentatonicism. Through incorporating these markers into his musical style, Debussy gives his music a French nationalistic stamp. I argue that the German philosopher Nietzsche shaped Debussy's nationalistic attitude toward musical exoticism. In 1888, Nietzsche asserted that Bizet's musical exoticism was an effective antidote to Wagner. Nietzsche wrote that music should be "Mediterranized," a dictum that became extremely famous in fin-de-siècle France. Nietzsche's influence on fin-de-siecle musical culture has not been examined in current secondary literature on French music. In my dissertation, I show that Nietzsche's dictum was widely discussed in the French press between 1893 and 1920. In periodicals from that time period, music critics such as Louis Laloy and Lionel de la Lawrencie contend that many French composers are following Nietzsche's dictum by writing exotic music. I aim to show that Debussy was one of the composers who followed this dictum. Influenced by Nietzsche's anti-Wagnerian view of exoticism, Debussy employed exotic markers as a nationalistic strategy of resistance against Wagner. In making this argument, my dissertation brings together three strands of Debussy's musical thought: nationalism, exoticism and anti-Wagnerism. Each of these strands has received previous scholarly attention, but scholars have not examined the links between them. My project demonstrates that Nietzsche gave Debussy the tools to combine these three strands in his compositions.