The Serpent (1916)

Peasant girl Vania is assaulted by a duke who murders her lover and sends her away to London. There she becomes a famous actress. The Duke, seeing her perform but not recognizing her, hears that his son is wounded. "If anything should happen to my boy, I think it would kill me." That's all the motivation Vania needs to go to the front, find the one-armed paralyzed boy and marry him. Next she arranges to make love to his father just as the boy enters the room, causing the young man to blow out his brains.