Thomas J. Wood, Kentuckian, graduated fifth in his West Point class in 1846 and joined the staff of General Zachary Taylor. The Mexican War was just beginning and Wood fought in several battles after which he served under General Winfield Scott in Mexico City. In 1861, Wood became a brigadier general of volunteers and began his Civil War service with the Army of the Cumberland, with whom he fought in every campaign and most of its major battles. Wood has never before been the subject of a full length biography but is well known for a notorious lapse of judgment resulting in a Confederate breakthrough at Chickamauga that shattered the Union right flank and threatened the survival of the Army of the Cumberland. It is a moment in the war still argued about. Wood learned from his mistake, became a better general from that time on (notably at Missionary Ridge and Nashville), and redeemed himself in the eyes of his fellow officers and his civilian superiors.