Smith was born in Mechanicsville, Tennessee. He attended the local schools before enrolling in the Nashville Military Academy. He received an appointment to the United States Military Academy in West Point, New York, but resigned and returned home. He subsequently took a position working for the Nashville & Decatur Railroad.
With Tennessee's Ordinance of Secession and the outbreak of the Civil War, Smith enlisted in the Confederate army as an officer in the 20th Tennessee Infantry. He first saw combat action at the Battle of Mill Springs in January 1862, and in April of that same year participated in the Battle of Shiloh. Later in the year, after being promoted to colonel of the 20th Tennessee and assigned command of a small brigade, he was part of the Confederate forces that unsuccessfully tried to seize the Union post at Baton Rouge, Louisiana. Confederate Army commander John C. Breckinridge remarked in his official report that Smith "moved against the enemy in fine style."
At the end of the year, he fought in the Battle of Stone's River, where he suffered a serious wound that put him out of action for much of 1863. After his recuperation, Smith resumed field duties, but was again wounded at the Battle of Chickamauga in September. After another lengthy recovery period, he returned to action during the 1864 Atlanta Campaign. He was promoted to brigadier general on July 29, 1864, and commanded an infantry brigade in the Army of Tennessee comprising the 2nd, 10th, and 20th Tennessee, the 37th Georgia, the 30th, 37th, and 50th Tennessee, consolidated, and a Georgia battalion of sharpshooters.
His military career ended at the Battle of Nashville on December 16. Union Colonel William L. McMillen, whose brigade had suffered heavily in an engagement with Smith's Brigade, reportedly attacked, captured, and disarmed the Confederate general with Smith's own sword (one source says "wantonly and repeatedly"). Smith's resultant brain injuries were so severe that for a time it was feared he would not live. Confederate General William B. Bate in his report stated, "General T. B. Smith, commanding Tyler's brigade, and Finley's, bore themselves with heroic courage both through good and evil fortune, always executing orders with zeal and alacrity, and bearing themselves in the face of the enemy as became reputations which each had heretofore bravely won." Held at Johnson's Island in Ohio and later at Fort Warren in Massachusetts, Smith was not released until July 24, 1865.
Smith recovered enough to be able to do some railroad work after the Civil War. He ran for a seat in the U. S. Congress in 1870, but lost the election. However, lingering effects of the savage beating caused permanent damage, and Smith spent much his last 47 years in an insane asylum in Nashville, emerging occasionally for army reunions and other social events.
He was buried beside many of his former comrades in the Confederate Circle of Mount Olivet Cemetery in Nashville.
- Evans, Clement, ed. Confederate Military History, Vol. VIII. Atlanta: Confederate Publishing Company, 1899.
- Warner, Ezra. Generals in Gray: Lives of the Confederate Commanders. Baton Rouge: Louisiana State University Press, 1959. ISBN 0-8071-0823-5.
- U.S. War Department, The War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies, 70 volumes in 4 series. Washington, D.C.: United States Government Printing Office, 1880-1901.