John Gregory Bourke kept a monumental set of diaries beginning as a young cavalry lieutenant in Arizona in 1872, and ending the evening before his death in 1896. As aide-de-camp to Brigadier General George Crook, he had an insider's view of the early Apache campaigns, the Great Sioux War, the Cheyenne Outbreak, and the Geronimo War. Bourke's writings reveal much about military life on the western frontier, but he also was a noted ethnologist, writing...