The Guns of Fort Petticoat (1957)

Lt. Frank Hewitt deserts the Union Army to warn former Texas neighbors of impending Indian attacks triggered by an Army massacre. He overcomes initial distrust and convinces the homesteaders (all women whose men are away fighting in the Confederate Army) to take refuge in an abandoned mission. He trains them to fight and shoot in anticipation of the attack. The only other man at the mission runs away to save his scalp and ends up leading the Indians back to the mission. Surrounded and outnumbered, the defenders prepare for the final assault.