The Legend of Custer (1968)

Lt. Col. George Armstrong Custer has been reinstated and assigned to command the 7th Cavalry Regiment at Fort Hays. The regiment has become a ragtag outfit of thieves and ruffians and Custer must whip the soldiers into shape to fight, the Kiowa, Sioux and Blackfoot tribes who confront them. These tribes are being supplied shotguns by a white gunrunner and Custer and his men must rescue General Terry and the Fifth Cavalry Regiment from annihilation when they are ambushed and trapped by a large Kiowa war party.

Unfortunately the movie The Legend of Custer is not yet available on HBO Max.