Goetz of Berlichingen of the Iron Hand(1979)

Sir Gotz von Berlichingen, a knight who fights for God and his Emperor, is the bitter enemy of the Bishop of Bamberg, who has managed to persuade Gotz's old friend Adalbert of Weislingen to fight for him. He allows Adalbert to kidnap him and bring him to his castle, where he tries to convince his old friend to come over from the "dark side". Complications ensue.