Soldier

During the American Revolutionary War, Mercer accepted a commission as lieutenant in the 3rd Virginia Regiment in the Continental Army. He was wounded at the Battle of Brandywine on September 11, 1777, and received a retroactive promotion to captain as of June 1777.^[5] On June 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 July 1779, but by October recruited a cavalry company for the Virginia militia as the British navy discharged the British Legion and others to raid plantations in Chesapeake Bay.^[4] Thus Mercer held the rank of lieutenant colonel and served briefly under Lafayette as he led troops at the Battle of Guilford, Battle of Green Spring, siege of Yorktown and other locations.

Virginia politician

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.^[6] 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.^[7]

Maryland planter

In 1785 Mercer married his wife, as discussed below, and soon moved to Anne Arundel County, Maryland, where he operated her estates ("West River Farm") using enslaved labor. Sophia Mercer had received land and slaves under the terms of her grandparents' wills (5 slaves from her grandfather in 1782 and 19 slaves from her grandmother in 1789), Mercer brought 24 slaves from Virginia in 1798-1799, and another 11 slaves between 1799 and 1801 (including at least 3 inherited from his mother).^[4] In 1810 Mercer sold his slaves and plantation equipment in Anne Arundel County to his namesake son John, which together with digitizing issues makes the precise number of slaves he owned in 1810 and 1820 unclear.^[8] and 1820.^[9] Mercer owned 72 slaves by the time he died in 1821, which with his other personal property was valued at $19,976.75.^[4]

Maryland politician

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.^[10] He also represented fellow anti-ratification delegate George Mason as a private lawyer collecting debts owed to Mason by Maryland residents.^[11] 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.^[12] He served terms in the lower house of 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. Despite owning slaves, Mercer was one of seven representatives to vote against the Fugitive Slave Act of 1793. ^[13]

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 Mercer 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.

Personal life

On February 3, 1785, he married heiress Sophia Sprigg (d. 1812), daughter of Richard Sprigg and Margaret Caile of Anne Arundel County, Maryland.^[14] They had at least four children, including Margaret Mercer, who became an abolitionist and freed all the slaves she inherited upon her father's death. Their son John Mercer (1788-1848), bought slaves and plantation equipment from this man (his father) in 1810 and received part of his maternal inheritance from his father in 1818 (when this man released his life interest in 606 acres of the 1478 acres his wife had re-patented in 1804) to him. That John Mercer married Mary Swann of Alexandria, Virginia and died in Virginia, and their other son Richard Mercer (by 1789-1821) did not have issue.^[15] His nephew, congressman Charles Fenton Mercer, opposed slavery and was president of the American Colonization Society.