John Francis Mercer (May 17, 1759 – August 30, 1821) was an American lawyer, planter, and politician from Virginia and Maryland, who served as Maryland's governor, as well as terms in the Continental Congress (representing Virginia), U.S. House of Representatives (representing Maryland districts), Virginia House of Delegates, and Maryland State Assembly A Founding Father of the United States, he was a delegate to the Philadelphia Convention which wrote the U.S. Constitution. Early and family life Mercer was born in 1759 at Marlborough plantation in Stafford County in the Colony of Virginia, to prominent lawyer, planter and investor in western lands John Mercer and his second wife, the former Ann Roy. His father John Mercer fathered 19 children by two wives, although many died before reaching adulthood. His namesake half-brother, Captain John Fenton Mercer (1735-1756)) was killed and scalped in western Virginia during the French and Indian War. His elder half brothers George Mercer and James Mercer served in the Virginia House of Burgesses, and James also became a prominent lawyer and served in Virginia revolutionary conventions, the Virginia House of Delegates and the Continental Congress (1779-1780) before becoming a judge, ultimately of what later became the Virginia Supreme Court. Mercer also had several sisters and half-sisters who survived to adulthood, including Sarah Mercer who married Col. Samuel Selden of Stafford County, Mary Mercer who married Daniel McCarty Jr. of Westmoreland County, Grace Mercer who married Muscoe Garnett of Essex County, and Maria Mercer who married Richard Brooke of King and Queen County. His younger brother Robert Mercer (1764-1800) would marry Mildred Carter, daughter of prominent planter Landon Carter, and become a lawyer and editor of the "Genius of Liberty". Like all his brothers who lived to adulthood, Mercer attended the College of William and Mary, and graduated in 1775. On February 3, 1785, he married heiress Sophia Sprigg, daughter of Richard Sprigg and Margaret Caile of Anne Arundel County, Maryland. 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. His nephew, congressman Charles Fenton Mercer, also opposed slavery and was president of the American Colonization Society. Career 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, and received a promotion to captain in 1777. On June