One other fascinating historical note about this film
One of the few men to receive two Medals of Honor (Gen Custer's brother was another one) was Sgt Dan Daly.
He earned his first in Pekiing; toward the end of the battle there were not enough men to man all the walls so some walls were manned and some were not. He volunteered to be posted 300 yards in front of one of the unmanned walls and from there fire a warning shot if the Chinese attacked. When they attacked his portion of the wall, Daly fired his shot, the Chinese then shot and stabbed him and left him for dead. After he regained consciousness, he patched himself up and to quote from the citation, "mounted an assault upon the enemy, taking them by surprise from the rear and re-captured the wall, which he held until reinforcements arrived."
The man is probably better known for the phase "Come on you sons of bitches, do you want to live forever?!", which he yelled at the Battle of Belleau Wood in WWI when he and some of the other Marines led the attack that took the German positions there. But, that's another story...