Which 1950 John Ford western completed his Cavalry Trilogy?

Rio Grande is the 1950 John Ford western that completed his Cavalry Trilogy.

The film followed Fort Apache (1948) and She Wore a Yellow Ribbon (1949), forming a loose group of stories about the U.S. Cavalry in the post–Civil War American West. John Wayne appears in all three films, but his character changes: he plays Captain Kirby York in Fort Apache and a promoted Lieutenant Colonel Kirby Yorke in Rio Grande.

Rio Grande stars Wayne opposite Maureen O’Hara as his estranged wife, Kathleen. The plot combines military duty with family conflict, as Yorke commands a fort on the Texas frontier while confronting raids, enlistment problems, and the unexpected return of his wife and son.

The screenplay was based on James Bellah’s short story “Mission With No Record.” Although the film’s action involves Apache raids, its historical inspiration was a controversial 1873 U.S. cavalry expedition across the Mexican border. The movie is also remembered for songs performed by the Sons of the Pioneers and for beginning Ford’s celebrated screen partnership with Wayne and O’Hara.