In June 1861, practically unschooled, without military training or experience, Nathan Bedford Forrest (1821-1877) enlisted in the Confederate Army as a private. Yet by the Civil War's end he was a lieutenant general whose dazzling exploits and bloody victories caused him to be regarded by his Northern opponents as a "devil," by Southerners as a living legend, and by historians as the greatest cavalry commander and one of the few authentic military geniuses produced by the war. His spectacular, unparalleled career has intrigued generations of Civil War scholars and enthusiasts. Subsequent...