The Smiling Lieutenant (1931)

Director: Ernst Lubitsch
Cast: Charles Ruggles, Claudette Colbert, George Barbier, Granville Bates, Hugh O'Connell, Maude Allen, Maurice Chevalier, Miriam Hopkins

Synopsis:

A simple wink, intended by Austrian palace guard Lt. Nikolaus von Preyn for girlfriend, Franzi, is accidentally intercepted — and misread — by the visiting Princess Anna. As a result, the soldier has no choice but to marry the royal lady and move with her to the neighboring kingdom of Flausenthurm. His girlfriend follows to continue the romance and, subversively, give Princess Anna tips on how to keep her husband satisfied.