Thomas-Antoine de Mauduit du Plessis or Thomas Duplessis or Thomas-Antoine du Plessis-Mauduit (12 September 1753 – March 1791) was a French officer who fought with the Continental Army during the American Revolutionary War. Born in Brittany, he ran away to sea at age 12 and voyaged in the eastern Mediterranean Sea for a time. Later, he attended a famous French artillery school. He was among a number of volunteers to join the fledgling American army in 1777, especially distinguishing himself for bravery at Germantown and skill at Red Bank. At Valley Forge he helped train American officers in the finer points of tactics and artillery handling.