This film is one of the better later-day John Wayne films, though strangely violent for a Wayne film. The Duke stars Jacob MacCandles (maybe a reflection of his real life family situation) as a tough man, estranged from his wife and grown sons. Bobby Vinton gives a quickie performance as Wayne's eldest son, shot when (the great) Richard Boone and his band of cutthroats nearly slaughter all on Jacob's ranch in the kidnapping of his grandson (played by Wayne youngest son Ethan). Patrick Wayne, his real son, plays second eldest son and youngest son, Michael, is played by Christopher Mitchum (Robert Mitchum's son!).
In tow are Wayne regulars, Harry Carey (disgusting tobacco chewing baddie), Bruce Cabot as the Indian tracker showing age with Jacob, Glen Corbett as breed the fast gun that faces off against Patrick Wayne in a gun fight, the most natural actor to ever grace the screen, the late Richard Boone, and a lovely appearance by the eternally beautiful Maureen O'Hara, once again playing John's long suffering wife whot loves him, but cannot live with him.
It is super to watch Wayne with Cabot, Carey, Boone and O'Hara, and Jim Davis (later rose to fame once more as Jock Ewing of Dallas) and though the film is intensely violent, I don't see it was gratuitous. The violence came from the end of a very violent era, times were changing, but not fast enough. The violence of the kidnappers had to be there to show Wayne's to-the-wall rescue of his small grandson was called for. Wayne's character was a violent man when the times called for it, but it was just as willing to let things go - if ONLY the other person walked away.
He worked well with his sons and Mitchum, and the interaction between Jacob and his two sons provides the Wayne brand humour in the film.
The times were changing for the code of the old west, and in the same way, times were changing for John Wayne....
I give Wayne credit for not pulling punches in a film that does him credit.