Not that novel, because other Westerns have featured the Mounties, not least "O'Rourke of the Royal Mounted", also known as "Saskatchewan" starring Alan Ladd, which had a similar theme of the Sioux crossing the border and stirring up trouble.
But "Fort Vengeance" (listed as "Fort Retribution" on some streaming services) did make a change from other 1950s Westerns and, interestingly, did not include an instant and improbable romance between an ageing star (such as Randolph Scott) and a very attractive girl. Rita Moreno provided enough peripheral feminine interest.
The fort did not seem very defensible and on several occasions its garrison (of 29 men, augmented by the two Ross brothers) was halved when patrols of a dozen or more policemen rode out.
No doubt experts could comment on the accuracy of the uniforms, which were changed some time in 1876. But a nice touch was two men wearing brown jackets and trousers ( issued for stables and other fatigues) when the two brothers arrived at the fort.
Goof-spotters may have noticed two horses tethered to one side of the fort gates and two civilians chatting on the other when a patrol rode out. They were still there when the patrol returned the following day!
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