Heartbreak (1931)

John Merrick and Vilma Walden, who fall in love at an embassy fundraiser in Vienna before World War I. Vilma's brother, Carl, who is a war veteran, poses as a rival for Vilma's affections. When war erupts, John requests a transfer to the Italian front, where he confronts Carl, who had borrowed his aircraft for a mission. John is devastated to learn the pilot he downed was actually Carl, leading him to announce he will no longer kill.