The Wonderful Country (1959), directed by Robert Parrish.
An American has been hiding out in Mexico so long he speaks English with an accent. Sent north of the border to buy guns for his patron he is laid up with a broken leg and finds himself between worlds, caught between north and south, the yankee and the spanish, the law and the outlaws.
This is a strangely paced, unconventionally structured western. Not successful at the time, it is better liked since but I think it will still be unsatisfying to many. Robert Mitchum is a character who can't win, scarcely in control of his fate. It's a good performance.
When the cavalry major's wife (Julie London, last seen in The Red House (1947)) flirts with him he is honest with her, pleading to be let off the hook. He has a chance for a fresh start and doesn't want to ruin it. That goes over poorly.
I don't think I've seen it before: the local cavalry unit are black troops. Their sergeant is baseball player Satchel Paige in one of his only two film roles.
Tough guy Charles McGraw is a friendly saw-bones.
Alex North score.
Available on Blu-ray from Kino. The Technicolor needs restoration.