Hangman's Knot (1952) on Netflix

Plot summary

Spring 1865 in Nevada: a band of Confederate soldiers in civilian clothes waylay a Union cavalry escort carrying gold bars across the eastern Sierra Nevada. After the fight, a dying Union officer tells Major Matt Stewart that the war ended a month earlier. At the rendezvous, Captain Petersen admits he knew and said nothing, and Rolph Bainter shoots him. Stewart decides the gold will help pay for the South's reconstruction, hides it in Petersen's wagon and heads out with his men. Drifters posing as a posse stop them; Stewart sends their leader, Quincey, off on a false trail. The mules bolt, so the rebels seize a stagecoach carrying Molly Hull and Lee Kemper, and Quincey's men chase them to a Sierra station house, where Stewart takes hostages.