How did Claude Debussy use the whole-tone scale in musical Impressionism?

Claude Debussy utilized the whole-tone scale—a series of six notes per octave separated entirely by whole steps—as a defining element of his musical style. By employing this scale, Debussy effectively bypassed the traditional major and minor scales that rely on half-step intervals.1

Because the whole-tone scale lacks semitones, it contains no leading tones or dominant harmony, which are essential for creating the sense of resolution found in functional tonality. Debussy used this to his advantage to suspend or dissolve the listener's perception of a key center. In his compositions, such as the piano prelude "Voiles," the absence of traditional harmonic contrast forces the listener to rely on melodic emphasis and repetition to establish a sense of structure. Consequently, his use of whole-tone harmony became a hallmark of Impressionism, marking a significant departure from the established tonal frameworks of the 19th century.1