Mason also practiced medicine in Alexandria, Virginia (part of the District of Columbia until 1847) and spent the American Civil War in Richmond working for the Confederate States Army.
The marriage produced four sons and four daughters who survived to adulthood (an elder brother George William Mason was born at Hollin Hall in 1791 and would move to Kentucky where he died in 1855).
Thomson Mason would serve in both houses of the Virginia General Assembly during his boy's childhood.
George Mason also served as one of Virginia's representatives to the federal Constitutional Convention in 1783, where he became known in part for his denunciations of slavery and the slave trade, and later became one of the most noted anti-Federalists at the Virginia Ratification Convention of 1788, though he died months before this boy's birth.
[1] His maternal grandfather, Richard Chichester (1736–1796), for whom the boy was named, was also a planter and local government official.
Mason received a private education appropriate to his class, then traveled to Philadelphia to attend the University of Pennsylvania School of Medicine.
George Mason had died on October 7, 1792, after training his three eldest sons including Thomson Mason (who shared the name with his lawyer uncle, who died before his brother) to operate using enslaved labor even before they reached reaching legal age to hold property.
[8] While practicing medicine in Alexandria (before retiring at age 45),[1] Mason also served as a justice of the peace in Fairfax County.
[13] Shortly after Virginia voted to secede from the Union at the beginning of the American Civil War, Union troops occupied Alexandria and commandeered Mason's house because of its proximity to the strategically important railroad which connected the town to the state capitol at Richmond.
Mason returned home at age 72 to find the mansion at Okeley had been used during the war as a hospital (particularly for infectious smallpox patients), then burned to the ground.