Search - Blood Song (Plainsmen, Bk 8)

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

The Battle of Powder River and the beginning of the Great Sioux War of 1876.
Frontier Scout Seamus Donegan is heading for Montana Territory with his new bride when war erupts in the Black Hills of Dakota. Sitting Bull and Crazy Horse have defied the Federal Government and refused to lead the wild tribes of the Northern Plains onto the reservation, and Washington decides to end the Indian problem once and for all.
Donegan joins up with General George Crook who is leading the 2nd and 3rd Cavalry and a rough-and-tumble band of scounts and interpreters into the bloody battle. For Seamus Donegan and the men on the front lines, the long fight in the bitter cold of winter will be one of loneliness and fear--a struggle for survival that will not end, even with the swift and successful assault on the enemy stronghold. For in the ashes on the snow, in the fury of defeated warriors, the seeds are sown for a new and even bloodier chapter in the Indian wars.