You might actually see that Native tribes fought for the US or the Colonies, depending on the war or battles. The Iroquois even split amoungst themselves, with some fight with the British, while others sided with the Americans.
Even with Custer, and the last stand, Crows went into the battle knowing full well they would not survive, and even after Custer released them from service, before the battle started. To this day, animosity still exists between the Crow and Lakota.