Rio Grande
Lt. Col. Kirby Yorke (John Wayne) is posted on the Texas frontier to defend settlers against attacks by marauding Apaches. Col. Yorke is under considerable stress between the Apaches using Mexico as a sanctuary from pursuit and by a serious shortage of troops of his command. The action of the movie is set in the summer of 1879 ("fifteen years after the Shenandoah").
Tension is added when Yorke's son (whom he hasn't seen in fifteen years), Trooper Jeff Yorke (Claude Jarman Jr.), is one of 18 recruits sent to the regiment. He had flunked out of West Point but immediately enlisted as a private in the Army. Not wanting to give any impression that he is showing favoritism towards his son, Col. Yorke ends up being harsher dealing with Jeff than the others. By his willingness to undergo any test and trial, Jeff is befriended by a pair of older recruits, Travis Tyree (Ben Johnson) (who is on the run from the law) and Daniel "Sandy" Boone (Harry Carey, Jr.), who take him under their wings.
With the arrival of Yorke's estranged wife, Kathleen (Maureen O'Hara), who has come to take the under-age Yorke home with her, further tension is added. During the war, Yorke had been forced by circumstances to burn Bridesdale, his wife's plantation home in the Shenandoah valley. Sgt. Quincannon (Victor McLaglen), who put the torch to Bridesdale, is still with Yorke and provides a constant reminder to Kathleen of the episode. In a showdown with his mother, Jeff refuses her attempt by reminding her that not only the commander's signature is required to discharge him, but his own as well, and he chooses to stay in the Army. The tension brought about in the struggle over their son's future (and possibly the attentions shown to her by Yorke's junior officers) rekindles the romance the couple once felt for each other.
Yorke is visited by his former Civil War commander, Philip Sheridan (J. Carrol Naish), now commanding general of his department. Sheridan has decided to order Yorke to cross the Rio Grande into Mexico in pursuit of the Apaches, an action with serious political implications since it violates the sovereignty of another nation.
If Yorke fails in his mission to destroy the Apache threat he faces the threat of court-martial. Sheridan, in a quiet act of acknowledgment of what he is asking Yorke to risk, promises that the members of the court will be men "who rode down the Shenandoah" with them during the Civil War. Yorke accepts the mission.
Yorke leads his men toward Mexico, only to learn that a wagonload of children from his fort, who were being taken to Ft. Bliss for safety, has been captured by the Apaches. After permitting three troopers—Tyree, Boone and Jeff—to infiltrate the church in the Mexican village where the Indians have taken the children, Yorke leads his cavalry in a full-scale attack, rescuing all of the children unharmed, though he himself is wounded. He is taken back to the fort by his victorious troops, where Kathleen meets him and holds his hand as he is carried on a travois into the post. After Yorke recovers, Tyree, Boone, Jeff and two others receive medals. At the ceremony, Tyree is given furlough to continue his run from the law, stealing Sheridan's horse for the purpose. As the troops pass in review, the movie closes.
murder