In the summer of 1879, Lieutenant Colonel Kirby Yorke (Wayne) is posted on the Texas frontier with the 2nd U.S. Cavalry Regiment to defend settlers against attacks by marauding Apaches. Yorke has just captured the Apache’s leader. Apaches have been using Mexico as a sanctuary from pursuit, and the regiment is suffering from a serious shortage of troops under Yorke’s command.
Yorke has been estranged from his wife and son for 15 years, after he set fire to his wife’s plantation under orders from his commander during the Civil War. Yorke’s son, Trooper Jefferson Yorke (Claude Jarman Jr.), is one of 18 recruits sent to the regiment. After failing mathematics and flunking out of West Point, he immediately enlisted as a private in the Army. In a meeting with his father, Yorke informs him that he will receive no special treatment in the brutal way of life he has chosen; Jeff declares he wants none. Through his willingness to undergo any test or trial, Jefferson befriends Travis Tyree (Ben Johnson) (who is on the run from the law) and Daniel “Sandy” Boone (Harry Carey Jr.). Yorke’s estranged wife, Kathleen (Maureen O’Hara), arrives unexpectedly to buy the underage Jefferson out of his enlistment. In a showdown with his mother, Jeff refuses her attempt to buy him out of the Army. The struggle over their son’s future rekindles the romance the couple once felt for each other.
The Apaches attack the fort one night. Many of them are killed by the awakened troopers, but they succeed in freeing their leader. When Yorke’s patrol reaches the Rio Grande, too late to capture the Apaches he was following, he meets a Mexican patrol. They exchange cordialities and both confirm that the US troops cannot cross into Mexico. Yorke is visited by his former Civil War commander, Philip Sheridan (J. Carrol Naish), now Commanding General of the Military Division of the Missouri, the headquarters responsible for pacifying the Great Plains. Sheridan has decided to order Yorke to cross the Rio Grande into Mexico in pursuit of the Apaches and kill them all, an action with serious political implications, since it violates the sovereignty of another nation. Sheridan, promises that if Yorke faces court-marshalling, will ensure that the members of the court are his fellow soldiers from the Civil War. Yorke accepts the assignment.
Before Yorke leads his men toward Mexico, he sends the women and children to Ft. Bliss for safety, with an escort including Jefferson. Jefferson and Boone meet Tyree, who is hiding from the law. Tyree informs them that there are Apaches in the area. The Apaches attack the wagons and capture the one carrying the children and corporal Bell’s wife. While the remaining escort fends off the Apache, Jefferson returns to the fort for reinforcements. Tyree saves him from an Apache attack on the way back.
The regiment meets the survivors of the escort and follows the Apache. They discover the burnt-out wagon and the body of corporal Bell’s dead wife, but there is no sign of the children. In the meantime, Tyree rejoins the regiment and tells them he trailed the Apaches to their hideout in Mexico. Working with Tyree, Yorke permits three troopers, Tyree, Boone, and Jefferson, to infiltrate where the Apaches have taken the children. Then Yorke leads his regiment in an all-out attack. The cavalrymen rescue all of the children unharmed, though Colonel Yorke is wounded by an arrow that he orders Jeff to remove. 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 Colonel Yorke recovers, Tyree, Boone, Jeff, Navajo Scout Son of Many Mules, and Corporal Bell are decorated. At the ceremony, when one of the Texas marshals reappears, Trooper Tyree is given a furlough to continue his run from the law, stealing General Sheridan’s horse for the purpose. As the troops pass in review, the regimental band plays Dixie at the General’s request, apparently to please Mrs. Yorke.
Watch the thrilling and action-packed Rio Grande online full movie to witness the tale of loyalty, family bonds, and a daring rescue mission unfold in the rugged terrain of the Texas frontier.