Last of the Comanches

It's 1876 and all the Indians are at peace except the Comanches lead by Black Cloud. When Black Cloud wipes out a town, only six soldiers are left and they head for the nearest fort. In the desert they are reinforced by members of a stagecoach and find some water at a deserted mission. Pinned down by Black Cloud they send an Indian boy who was Black Cloud's prisoner on to the fort while they try to bargain with Black Cloud whom they learn is without water..