8, 1778 he became an aide-de-camp with the rank of major to General Charles Lee. He resigned from the army when Lee did in October 1779, but recruited a cavalry company for the Virginia militia as the British navy discharged Tarleton's Raiders and others to raid plantations in Chesapeake Bay. Thus he held the rank of lieutenant colonel and served briefly under Lafayette as he led troops at the Battle of Guildford, Battle of Green Spring, siege of Yorktown and other locations. After General Cornwallis' surrender in 1781, Stafford County voters elected Mercer as one of their two representatives in the Virginia House of Delegates in 1782, where he served alongside Charles Carter. Fellow legislators selected Mercer as one of Virginia's delegates to the Continental Congress in both 1783 and 1784. When Richard Brent died, a special election to fill his place as Stafford County's delegate to the Virginia House of Delegates was held, and John Francis Mercer took his place for the rest of the session. In 1785 Mercer married his wife, and soon moved to Anne Arundel County, Maryland, where he operated her estates using enslaved labor. He owned slaves in 1810 and 1820. Mercer owned 72 slaves by the time he died in 1821. Meanwhile, Mercer became one of Maryland's delegates to the Philadelphia Convention in 1787, but because he was opposed to centralization, withdrew before signing the Constitution. [He also represented fellow anti-ratification delegate George Mason as a private lawyer collecting debts owed to Mason by Maryland residents.] Mercer was also a delegate to the Maryland State Convention of 1788, to vote whether Maryland should ratify the proposed Constitution of the United States. He served terms in the Maryland State Assembly in 1788-89 and 1791-92 before being elected to represent Maryland in the United States House of Representatives from the second and third districts from 1792 to 1794, resigning on April 13, 1794. He again served in the Maryland House of Delegates (1800-1801) before winning election as the tenth Governor of Maryland (for two one-year terms) from 1801 to 1803. Although he again served in the Maryland House of Delegates in 1803-1806 (and joined with the Federalists during Thomas Jefferson's Presidency), illness plagued Mercer in his later years Death and legacy Mercer traveled to Philadelphia, Pennsylvania to seek medical attention, and died on August 30, 1821. Although a funeral was held at St. Peter's Church in