Thomas Glascock, Jr. was born in Augusta, Georgia on October 21, 1790, seven years after the end of the American War of Independence. He studied law, gained admission to the state bar, and began practicing law in a career path that would underpin his later political service. Both his father and grandfather had distinguished themselves in military and political service to the new United States. Brigadier General Thomas Glascock Sr. rescued Count Casimir Pulaski from the Siege of Savannah, while serving in Georgia in the Virginia Dragoons during the American Revolution. General Glascock's subsequent appointment as "Marshal of Georgia" was conferred upon him by President George Washington on May 31, 1794. Thomas Jr's grandfather was Colonel William Glascock, who was acting governor of Georgia for a period during the American Revolution at Augusta. President George Washington stayed with William at the Glascock family plantation in Augusta during his presidency.