George Bird Grinnell (1849–1938)

From 1864 until 1877, the Pawnee Scouts, a unique U.S. Army battalion of about a hundred Pawnees, were scouts and soldiers during the height of the Plains Indian wars and earned the respect of prominent generals in the West, including George Crook, Eugene Carr, and Ranald Mackenzie. They were commanded by the famous "fighting Norths."
Originally published in 1928, Two Great Scouts and Their Pawnee Battalion is based upon Luther's firsthand recollections.

An interesting book to read concerning the history and dealings of the US government and the plains Indians specifically the Cheyenne tribes. A little dry at times and as it was written in the early 1900's a little condescending this is still the closest to actual first hand accounts from the Native Americans involved in many of these battles as you are likely to get.