After the American Civil War, highly respected veteran Captain Kirby York (Wayne) is expected to replace the outgoing commander at Fort Apache, an isolated U.S. cavalry post. York had commanded his own regiment during the Civil War and was well-qualified to assume permanent command. To the surprise and disappointment of the company, command of the regiment was given to Lieutenant Colonel Owen Thursday (Fonda). Thursday, a West Point graduate, was a general during the Civil War. Despite his Civil War combat record, Lieutenant Colonel Thursday is an arrogant and egocentric officer who lacks experience dealing with Native Americans, and in particular local tribes with their unique cultures and traditions.