His sadness during World War I hastened the deterioration of his health. He died during the bombardment of Paris by German artillery. Debussy's style was one of the most important influences on 20th- century music. As a student he refused to submit to the rules of traditional musical theory. You have only to listen.
Pleasure is the law.
He rejected the overblown forms and the harmonic style of the post-Wagnerians such as Gustav Mahler and Richard Strauss. He preferred understated effects similar to those achieved by the French impressionist painters and poets. Pelleas et Melisande, the most significant impressionist opera, has been called a masterpiece of understatement. He wanted his music to sound improvisatory, as though it had not been written down. Debussy's piano music is the most important since Chopin's.