After the disastrous defeat of Allied troops in the Battle of France in 1940, German occupation of France during WWII began. Life and music in Paris came to a screeching halt.
The lively jazz culture and effusive music that had recently washed onto France's shores soon fell victim to the Nazi invasion. Essentially, jazz became an illegal music. Once celebrated artists, jazz performers fled in exile to avoid the heavy hand of German occupation.
In Hitler's eyes, music was a crucial combat zone in his war for racial purification. Hitler declared jazz to be a "degenerate music" just as he had so famously done to certain Western Classical composers like Mendelssohn and Mahler.Music has always played an important role in patriotism. National anthems, marches, and hymns have celebrated and united countrymen throughout history. Hitler recognized jazz's power and waged a dedicated effort to completely irradicate it.
Jazz was a crucial target for the fascist embargo of American culture because it celebrated triumph over oppression, hope in the face of overwhelming adversity, and individual freedom. These were threatening concepts to the Nazi movement which relied on conformity, blind obedience, and manipulation. To Hitler, music represented a major part of his totalitarian vision. He didn't simply want to oppress and control. He wanted to dominate every aspect of French thought, culture, and life.
Despite the Nazi war on jazz, some French musicians continued to secretly perform as a symbolic form of protest. Since jazz in France came to exist in total isolation, it was very frozen in time. The innovations and contributions of America artists were inaccessible. As a result, French jazz became somewhat dogmatic. After the Allied Liberation, many French jazz musicians clung stubbornly to the "New Orleans" style of Duke Ellington although Bebop was now ruling US airwaves.
During WWII, it became a symbol of liberation vitally important to resistance-minded individuals trapped in occupied France. One of France's greatest jazz commentators, Boris Vian argued that "under the Occupation, [jazz] created a secret, subtle world where youth could find refuge." Despite his myriad attempts, Hitler was never able to permanently silence the music. The potency of jazz's lively, optimistic message helped many French people to discreetly cope with the difficulties of life in occupied France.
For more historical jazz commentary, read Jazz, Josephine Baker, and France