Search - Black Sun: The Battle of Summit Springs, 1869 (Plainsman, Bk 4)

"Grueling winter gave way to bloody spring as Seamus Donegan and his fellow Army scouts rode west with the Kansas Pacific Railway. Led by the legendary "Buffalo" Bill Cody, they withstood blazing hit-and-run raids by Cheyenne Dog Soldiers--while trailed by a skulking enemy from Donegan's past. Then, in midsummer, the fleeing Cheyennes camped. And the 5th Cavalry mounted the brutal surprise attack that would give rise to a fierce new warrior-leader named White Horse: the Battle of Summit Springs, 1869."

Great Book! As are all of his books. I recommend them all.