24 Sept. 1754–6 Jan. 1785
William Caswell, North Carolina adjutant general in the Revolution, Continental army captain, county official, state legislator, and planter, was the son of Governor Richard Caswell and his first wife, Mary Mackilwean. He was born at the Red House, a family plantation then in Johnston County. The home stood near the present site of the Governor Richard Caswell Memorial Park in Kinston, Lenoir County.
William received his early education from family members and from local schoolmasters. After he was ten years old, the school at the Herritage Chapel in Kinston, near the Caswell home, was taught by the Reverend William Miller, an Anglican clergyman. All Governor Caswell's sons received training by apprenticeship for careers in the law. By 1774, William was serving as register of deeds of Dobbs County (formed from Johnston in 1759) under the tutelage of his uncle, Martin Caswell, long-time clerk of the Dobbs County Court. On 3 Sept. 1774, William went to Philadelphia with his father, on horseback, to attend the First Continental Congress. He kept a daily diary of his travels and a careful account of his expenses, now preserved in the state records of North Carolina and mistakenly attributed to Governor Caswell himself.
Upon his return to Kingston (renamed Kinston in 1784), William Caswell resumed his legal training and his work as register of deeds of Dobbs County. While his father was attending a later Continental Congress in May 1775, William received his first inkling of the hardships and dangers soon to be his lot as a soldier of the Revolution. A letter from his father, written from Philadelphia on 11 May 1775, described the growing spirit of Revolution and advised him to prepare to risk his life in the service of his country. He was commissioned an ensign in the Second Regiment of the North Carolina Continental Line 1 Sept. 1775. With other Continentals from the New Bern District, he was dispatched to join General Washington's forces in the North, where important campaigns against powerful British forces were impending. He served with valor in campaigns there for more than three years and suffered wounds at the Battle of Brandywine. He was with General Washington's army during the miserable winter at Valley Forge. Afterward, he was transferred to the Fifth Regiment of the North Carolina Continental Line, in which he was captain of Caswell's Company; in 1778 he was sent home in failing health.
Under the constitution of North Carolina adopted in December 1776, only members of the state legislature were elected by the people. All other state officers were elected by the General Assembly, which held two sessions in 1779. Thomas Gray and Captain Jesse Cobb represented Dobbs County in the first session, and William Caswell was elected to the House of Commons in the second session. He was also returned by the voters of Dobbs County in the general elections of 1780, 1781, 1782, and the second session in 1784.
Soon after Caswell's return home from the army in 1778, he was commissioned colonel of a large detachment of troops sent to the aid of South Carolina and Georgia. His commanding officer on this expedition, General John Ashe, urged upon the state board of war the need to commission a state adjutant general and recommended Caswell for the post. At a meeting of the board of war held in Tarboro on 4 Jan. 1779, Caswell was commissioned adjutant general with the rank of brigadier. He was one of the colonels under command of General Ashe at the Battle of Brier Creek near the Savannah River in Georgia in 1779; and later, as brigadier general, he led a command at the Battle of Camden, S.C., under General Horatio Gates, an engagement that resulted in a disastrous defeat. Caswell's forces supported General Nathanael Greene's operations against the British forces under General Cornwallis in 1780–81 and continued to carry out supporting operations against the British until Cornwallis's army surrendered.
After the war, Caswell lived at his plantation near Kinston, meantime serving as a state legislator and a justice of the county court. On 22 Dec. 1782 he was married in Dobbs County to Gathra Mackilwean, a daughter of his mother's brother, Francis Mackilwean, and his wife, Mary. William and Gathra had one child, Richard William, born on 17 May 1784 at Kinston.
Caswell died at Kinston and, according to his father's will, was buried in the family cemetery there. His grave is unmarked. His wife, affectionately called Gatsey, died later that same year.