Col. William Grayson(1740–1790) was a soldier, lawyer, and statesman. Col. Grayson practiced law in Prince William County and is frequently mentioned as a guest at Mount Vernon, and as a hunting companion of George Washington. At the outbreak of the American Revolution, he served as a captain of the local militia but left the Virginia forces to become an aide-de-camp to General Washington. He later took command of one of the sixteen regiments of the Continental Army. After a bloody battle at Monmouth, New Jersey that virtually destroyed his entire regiment, Col. Grayson went on to serve on the Board of War. After the war, he served as a member of the Continental Congress and was later one ofVirginia’s first two Senators.

Col. Grayson died in Dumfries on 12 March 1790, the first member of the United States Congress to die in office. He was interred in the Grayson family vault in Woodbridge on a hill overlooking Marumsco Creek. The family burial vault, originally located on a one thousand acre plantation; now, less than five acres remain undeveloped. The vault now sits amid a Woodbridge residential neighborhood. It was encased in concrete in the early 1900s by the Daughters of the American Revolution, and has been recently repaired and made accessible to the public. The Reverend Spence Grayson, a “fighting parson” of the Revolution and lifelong friend of George Washington, is also buried in the vault.