Rio Bravo (1959)

Sheriff John T. Chance has his hands full after arresting Joe Burdette for murder. He knows that Burdette's brother Nathan, a powerful rancher, will go to any lengths to get him out of jail. Chance's good friend Pat Wheeler offers to help but within 20 minutes of making the offer is gunned down in the street, shot in the back. That leaves his elderly deputy Stumpy, the town drunk Dude, once a deputy and a pretty good shot when he was sober, and a young hand, Colorado, who used to work for Wheeler. Nathan Burdette meanwhile has a couple of dozen men at his disposal. Chance does his best to prepare all the while romancing a pretty gambler who goes by the name of Feathers.

IMDb: https://www.imdb.com/title/tt0053221