Despite officially joining the Confederacy in 1861, Tennessee provided the Union with nearly 32,000 troops during the Civil War. Representing a Southern opposition to secession and loyalty to the Union, many of these Tennesseans served as cavalry or as mounted infantry. Among those serving on horseback were Samuel P. Carter, who temporarily left his post in the U.S. Navy to command a cavalry brigade; Pres. Andrew Johnsons son, Robert Johnson, who served as colonel of the 1st Tennessee Cavalry; and James Brownlow, son of Tennessees Reconstruction governor, who led his command in a naked charge...