Shortly after the outbreak of the
American Revolution, Sargent was commissioned in
Gridley's Regiment of Massachusetts Artillery on July 7, 1775, as a
lieutenant, and later that year was promoted to
captain lieutenant of Knox's Regiment, Continental Artillery, on December 10. He was with his guns at the
siege of Boston, and later served in the battles of
Long Island,
White Plains,
Trenton,
Brandywine,
Germantown, and
Monmouth. He was promoted to
captain in the 3rd Continental Artillery on January 1, 1777, and
brevetted
major on August 25, 1783, and was discharged from the Continental Army later that year. Sargent was appointed by the
Congress of the Confederation as the first Secretary of the Northwest Territory, a post second in importance only to the governor,
Arthur St. Clair. He took up his post in 1788. Like St. Clair, Sargent would function in both civil and military capacities; he served as acting Adjutant General of U.S. Army from September 1791 until he was wounded twice at the
Battle of the Wabash, on November 4, 1791. His last entry as Northwest Territory's secretary was on May 31, 1798; he arrived at
Natchez on August 6, but due to illness was unable to assume his post until August 16. The subject was a cotton planter, marketing his crop in New York by Gilbert and John Aspinwall, merchants.
Later life In 1788, Sargent was elected a Fellow of the
American Academy of Arts and Sciences. He was also a member of the
American Philosophical Society elected in 1789 and an original member of the
Society of the Cincinnati as a delegate from
Massachusetts, and published, with Benjamin B. Smith,
Papers Relative to Certain American Antiquities (Philadelphia, 1796), and "Boston," a poem (Boston, 1803). Being a Federalist, Sargent was dismissed from his position as territorial governor of Mississippi in 1801 by incoming president
Thomas Jefferson. Sargent took up life in the private sector, developing his plantation
Gloucester, the earliest such establishment in
Natchez. Sargent was elected a member of the
American Antiquarian Society in 1813. During the last decades of Winthrop's life he became major plantation owner in [Natchez, Mississippi]. He acquired extensive plantations due to his marriage to wealthy widow Mary (McIntosh) Williams. In Natchez alone Winthrop owned over 300 slaves and 11,000 acres. ==Personal life==