The tenth child and sixth son born to Stephen Thomas (1705-1774) and Mary Clothier Thomas, his family moved from Maryland to North Carolina shortly after his birth. With some of his older brothers, he later moved to South Carolina ca. 1769 and settled in the area that became Marlboro County. Through grants he received a total of 4250 acres of land between the Great and Little Pee Dee rivers. At death, he owned thirteen slaves. Active in the military during the American Revolution, he was commissioned 1 Jul 1775 as a sergeant in a company of rangers. He later served as a captain (1780,81) and major (1781). In late July or early August 1780, he commanded a Whig party which captured a British expedition at Hunt's Bluff on the Pee Dee. After the war, he held the rank of brigadier general of the Ninth Brigade (ca. 1794-1804). 
Legislative service began for him when he was elected by St. David's Parish to the House of the Fourth General Assembly (1782). Representing his home parish, he served in the Senate during the Fifth General Assembly (1783-84). Winning a special election in St. David's, he was returned to the House for the Sixth General Assembly (1785-86), qualifying 31 Jan 1786. The election district of Marlboro, Chesterfield, and Darlington counties elected him to the Senate for the Eleventh (1794-95) and Twelfth (1796-97) General Assemblies. During the Twentieth General Assembly (1812-13), he served once more in the House, representing Marlboro County. Chosen by St. David's, he was a delegate to the state convention to adopt the federal Constitution but was absent when the vote on ratification was taken (1788). Furthermore, he held a variety of local offices; overseer of the poor for St. David's (1778); commissioner, for dividing Cheraw District into counties (1783); justice of the peace for Marlboro County (1785); road commissioner (1786, 1796, 1805); commissioner, to open and improve navigation of the Great Pee Dee River from the North Carolina line to Black Creek (1789,91); county court judge for Marlboro (1791); commissioner, to build and repair a courthouse and jail in Cheraw District (1794); commissioner, for the removal and safekeeping of the records of the clerk's office of the Cheraw District Circuit Court (1794); commissioner, to open and keep in repair a canal leading into the Pee Dee River (1796); trustee of the Marlboro Academy authorized to conduct a lottery (1802); and commissioner, to superintend repairs to the courthouse in Marlboro District (1810). A member of the Welsh Neck Baptist Church, he was a messenger to the Charleston Baptist Association (1785,91,93,95,1800,02,03). In 1778, he subscribed to the St. David's Society. 
Tristram Thomas was twice married. First, to Ann Pledger, who died ca. 1779, daughter of Capt. Philip Pledger, and mother of three children: Robert Turner Thomas (1775-1819) m. Jane House; Susannah Thomas (1777-1841) m. Joseph Thomas, a first cousin; and Philip Thomas (1779-1837) m. Martha Washington Hodge. 
After the death of his first wife, Gen. Thomas remarried to Mary Hollingsworth, daughter of Samuel Hollingsworth and widow of David Harry. She was the mother of five Thomas children: Elizabeth Thomas (1781-1856) m. first to Joseph Burch, Jr. and second to Archibald "Arch" Caraway; John Thomas, b. 1784; Sarah Thomas, b. 1785, m. Josiah David; Tristram Hollingsworth Thomas, b. 1789 m. Martha Davis; and James Clothier Thomas (1792-1867) m. Mary L. Davis. 
Tristram Thomas was a name respected and honored and respected by all classes on the Pedee. General Thomas was modest and retiring in disposition, but firm and decided whenever principle was involved in the conduct of life. Sturdy by habit, and resolute in character as circumstances might demand, he was happily fitted by nature for the perils and labors of the Revolution. The discouragements to which the actors of that stormy period were often subjected, never unnerved or intimidated his soul. Possessed of a solid understanding, a practical turn of mind, and virtuous principles, he faithfully discharged the duties incumbent upon him in every station to which he was called in the administration of the affairs of his own district and the councils of the State. He was the first Brigadier-General on the Pedee after the war. He lived to a good old age, universally esteemed and died at his residence in Marlborough District in 1817. 
(SOURCES: Biographical Directory of the South Carolina Senate and Gregg's History of the Old Cheraws.)
From:  https://www.findagrave.com/memorial/32037726