The Vultures Are Hungry (Two Mules for Sister Sara)

Cynical Secession War veteran Hogan (Clint Eastwood) is in Mexico to earn a fortune trading arms to the Juarista rebels against the French troops of Emperor Maximilian. He takes pity, with ever more mixed feelings, on maverick nun Sara (Shirley MacLaine), who is pursued by French cavalry. Godless Hogan never picks up that she's ignorant in religious matters, while obviously the contrary in anything profane. Stuck on the wrong side of Mexican law and facing the semi-hostile Yaqui tribe, they mutually confide and find both to be heading for a French fort to be taken by the Juaristas, whose rustic "Colonel" Beltran (Manolo Fabregas) only leads a bunch of war-ignorant peasants and requires him to fetch explosives from Texas. Only after they bond in several adventures, he learns her true crime and identity.