When Charlie Chaplin watched “Triumph of the Will,” his immediate impulse, according to Luis Buñuel, was to burst into laughter. The orator onscreen seemed to be an insane variation on Chaplin’s Little Tramp persona, down to the toothbrush mustache. The experience unnerved him, though, as it did many leftist filmmakers who witnessed the technical virtuosity of German cinema being applied to sinister ends. In 1940, Chaplin released “The Great Dictator,” a lavish satire of Hitler’s histrionics. Inevitably, Wagner is on the soundtrack, yet Chaplin makes the surprising choice to detach the music from the Nazi context. The ethereal prelude to “Lohengrin,” suggesting the sacred power of the Holy Grail, is heard twice in the film, serving first to puncture Nazi iconography and then to amplify a message of peace.