William Smallwood was an American planter, soldier and politician from Charles County, Maryland. He served in the American Revolutionary War, rising to the rank of major general. He was serving as the fourth Governor of Maryland when the state adopted the United States Constitution. When the American Revolutionary War began, Smallwood was appointed a colonel of the 1st Maryland Regiment in 1776. He led the regiment in the New York and New Jersey campaign. For their role in the Battle of Brooklyn on August 27, 1776, when the Maryland Regiment heroically covered the hasty retreat of the routed Continental Army, General George Washington promoted Smallwood to brigadier general. On December 21, 1777, Smallwood commanded 1,500 Delaware and Maryland troops at the Continental Army Encampment Site on the east side of Brandywine Creek, to prevent occupation of Wilmington by the British and to protect the flour mills on the Brandywine. Smallwood briefly commanded the militia forces of North Carolina in late 1780 and early 1781 before returning to Maryland, staying there for the remainder of the war.

He resigned from the Continental Army in 1783 and later that year was elected to serve as the first president of the newly established Society of the Cincinnati of Maryland. Smallwood was elected to Congress in 1784, but before he could take his seat, the Legislature chose him to succeed William Paca as Governor of Maryland. Smallwood had the misfortune of serving as governor during one of the most difficult periods in the history of the nation. Not only were the Articles of Confederation proving inoperable, but the country also found itself in the midst of an economic depression. Smallwood never married. The 1790 United States census reveals that he held 56 slaves and a yearly tobacco crop of 3000 pounds. When he died in 1792, his estate, known as Mattawoman, including his home the Retreat, passed to his sister Eleanor who married Colonel William Grayson of Virginia.