Thomas B. Smith was born around 1830 in Arkansas. He married a woman named Mary around 1850, and they had at least five children: Nancy, born around 1853; Martha, born around 1854; Mary, born around 1855; Cynthia, born around 1857; and Sarah, born around 1859. They lived in Tennessee until around 1854, when they moved to Alabama. They moved to Texas around 1856, and by 1860, they were living in Canton, Texas. By 1860, Smith was working as a schoolteacher, and he owned $500 of real estate and $100 of personal property.
He sided with the Confederacy during the Civil War. On February 8, 1862, he received a commission as a 2nd lieutenant in Company I of the 11th Texas Infantry. He was eventually promoted to captain, and he died in 1864.