The Outriders

The Outriders is a 1950 western film starring Joel McCrea.

The men see it as a chance to help the South and also profit. Don Chaves is suspicious of them, but permits them to be outriders, accompanying the wagon train but staying 200 yards from the others. Apaches attack and the three men help fend them off, gaining the Dons trust.The beautiful widow Jen Gort attracts the interest of Will and Jess, who have a falling out. She is escorting teenaged Roy, her young brotherinlaw, who is eager to prove his courage to the older men by fighting Indians by their side. The boy ends up inadvertently causing a stampede, however, then drowns while attempting to cross a raging river. ........

Source: Wikipedia