The story of Spotted Tail and his people is the story of the deadly game of resistance and subjugation. The government expected the Sioux to live on a reservation, to farm the land, raise cattle, send their children to school, and adopt Christianity - all at once. Spotted Tail understood that the Brules could not be turned into imitation whites overnight, and he fought to protect his people from being rushed into the white man's ways by government agents and eastern "Friends of the Indians.".
This is also an excellent book by Mr. Hyde - I also view it as an exceptional read and it focuses on the Brule Sioux and a lot about what is now the Rosebud Sioux Reservation - the rivalry between Red Cloud and Spotted Tail, and history of the Sioux Tribes I loved it.
I've also seen other respected academic historians refer to it as an excellent source. I highly recommend it.