Robert M. Utley is a preeminent historian of the West and the author of numerous award-winning books, including The Last Days of the Sioux Nation; Custer and the Great Controversy: The Origin and Development of a Legend (Nebraska, 1998); and Billy the Kid: A Short and Violent Life (Bison Books, 1991); as well as the authoritative Frontier Regulars: The United States Army and the Indian, 1866-1891 (Bison Books, 1984).