France in the 1930s saw three waves of avant-garde cinema movements that experimented with narrative forms and visual styles, including Impressionism, Dadaism, and Surrealism. The third avant-garde was ended by the introduction of sound film which raised production costs. Poetic realism then emerged, combining lyricism and realism through techniques like deep focus shots and sequence shots. Films from this era also explored more complex human relations beyond good and bad guys. Renoir's 1937 film Grand Illusion addressed the senselessness of war and promoted humanism, but was banned in Germany as Goebbels viewed it as cinema's biggest enemy.