Without the benefit of a college education, Miles attained the rank of major general of volunteers two months after his twenty-sixth birthday. At the close of the Civil War, he was Jefferson Davis's military jailer, then served with the Freedmen's Bureau in North Carolina. On the frontier, he won a series of victories against the Kiowa-Comanches, Sioux, Nez Perce, Bannocks, and Geronimo's band of Apaches. His skillful management of the Messiah outbreak of 1890 ended the Indian Wars. Miles also commanded the Army during the Spanish American War and was involved in the late nineteenth-century Army reforms.

During his long and distinguished career, Miles made numerous enemies, including Theodore Roosevelt. Peter DeMontravel contends that the comments made by these enemies influenced the way historians have viewed Miles's career. This reassessment of that career restores him to a degree of prominence.