Ravenous (movie, 1999)

Upon receiving reports of missing persons at Fort Spencer, a remote Army outpost on the Western frontier, Capt. John Boyd investigates. After arriving at his new post, Boyd and his regiment aid a wounded frontiersman who recounts a horrifying tale of a wagon train murdered by its supposed guide -- a vicious U.S. Army colonel gone rogue. Fearing the worst, the regiment heads out into the wilderness to verify the gruesome claims.