Franck continued to write compositions for choir in this period, but most were never published. As was then common even for Conservatoire-trained musicians, he had never become familiar with the polyphonic music of earlier centuries. Franck composed his liturgical works in the then-current style, which Davies characterizes as "secular music with a religious bias". Nevertheless, he was encouraged to begin work (1869) on a major choral work, "Les Béatitudes", which was to occupy him for more than ten years, the delay partly due to the interruptions of the Franco-Prussian War. The war, like the 1848 Revolution, had caused many of his pupils to disappear, either because they left Paris or were killed or disabled in the fighting. Again he wrote some patriotic pieces which, in the harshness of the times, were not then performed. He and his family experienced economic hardships as his income dropped and food and fuel became scarce. The Conservatoire was closed for the academic year 1870–1871. But a change was coming in how French musicians regarded their own music; particularly after the war they were looking for an "Ars Gallica" that would be distinctly French. The term became the motto of the newly founded Société Nationale de Musique, of which Franck became the oldest member; his music appeared on its first program in November 1871.