Davy Crockett, Indian Scout (1950)
It's 1848 and a wagon train with an Army escort is heading west through Indian territory, It's scout is Davy Crockett, nephew of his more famous namesake. There is spy amongst them informing the Indians. They survive the first Indian attack and then push on. They have a choice of two passes through the mountains. Learing of the pass to be defended by the Indians, they head for the other. But upon ariving, the Indians attack. Somehow they have been informed.