Grayson was ordained an Anglican priest in England in 1771, he served as rector of Cameron and Dettingen parishes in Prince William County, so both brothers socialized with Rev. Scott of Pohick Church both vestries. American revolutionary Grayson became involved in the political prelude to the Revolution in Virginia. He was on various Committees of Correspondence and military preparedness, as did nearby planters, including Richard Henry Lee with whom he would serve as the inaugural U.S. Senators from Virginia. In June 1776 he became an assistant secretary to George Washington, and was promoted as an aide-de-camp to Washington in August, which came with the rank of lieutenant colonel. In January 1777, William Grayson recruited a regiment for the Continental Army known as Grayson's Additional Continental Regiment, and served as its colonel (and Spence as its fighting chaplain). The Regiment was attached to General Charles Scott's Brigade and saw frequent action in late 1777 in the Philadelphia Campaign, notably in the delaying skirmishes in Northern New Jersey, the Battle of Brandywine and the Defense of Philadelphia. In the winter of 1777-78, he led his troops to Valley Forge, where they suffered privations, and emerged in the spring with considerably fewer men fit for service. On June 28, 1778, Grayson was central to the Battle of Monmouth. In Scott's absence, Colonel Grayson took temporary command of the brigade, which was in the vanguard of an assault as part of Charles Lee's Advance Guard. Grayson and the brigade were in the center of the battle in 100 degree heat, and held a far superior force to a stalemate, when Lee took personal command of all of his forces, while Grayson himself returned to Washington's field command. General Lee badly misunderstood intelligence he was receiving, and the line broke into a disorganized retreat. Subsequently, Lee was court-marshalled by Washington, and Grayson, as one of the key officers at Monmouth, had to testify at the proceedings. In 1778, William Grayson served on a commission dealing with war prisoners. In 1779, he resigned his military commission to serve on the Congressional Board of War. Post-War career In 1781 Grayson returned to Dumfries and his legal practice. Like many Continental Army officers, he was an original member of the Society of the Cincinnati. He was also elected as a member to the American Philosophical Society in 1780. Like his brothers, Grayson owned slaves. In the 1787 Virginia