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.
He defended a key position at Monmouth in the summer of 1778. Receiving permission to resign from the American army at the end of 1778, he later fought with Jean-Baptiste Donatien de Vimeur, comte de Rochambeau's army. In 1787, he took command of a regiment in Haiti. He resisted the French Revolution, refusing to carry out instructions from the new government. Instead, he carried out a repressive counter-revolutionary program which provoked a revolt. When reinforcements arrived from France in March 1791, the new soldiers immediately took the side of the revolutionary faction. Stirred up, du Plessis' own regiment rioted and his men murdered him.
Early career
Du Plessis was born in Hennebont in Brittany on 12 September 1753. Sent to the famous artillery school in Grenoble at a very young age, he ran away to Marseilles when he was 12 years old. Joining a ship's crew as a seaman, he satisfied his thirst for travel by sailing to the Levant, Alexandria, and Constantinople. Eventually he returned to France and his military studies.
In December 1776, Philippe Charles Tronson de Coudray and a group of French officers left for America on the Amphitrite. The ship was soon forced to turn back to France. Anxious to get on with their journey, Lieutenant du Plessis and Philippe Hubert Preudhomme de Borre went aboard the Mercure. Du Plessis paid 400 livres for the price of his passage. Carrying a secret cargo of military supplies, the vessel left Saint-Nazaire on 5 February 1777. The Mercure reached Portsmouth, New Hampshire on 17 March and de Borre arrived at Morristown, New Jersey exactly two months later. Appointed captain of artillery in the Continental Army, du Plessis' commission dated from 15 April 1777. He fought at the Battle of Brandywine on 11 September.
Germantown and Fort Mercer
At the Battle of Germantown on 4 October 1777, the American offensive stalled when Lieutenant Colonel Thomas Musgrave and 120 British soldiers of the 40th Foot stoutly defended the Chew House. After artillery and infantry assaults failed, du Plessis and other officers attempted to set the house on fire. To fellow aide John Laurens, du Plessis suggested the idea of fetching hay from the nearby barn and using it to ignite the structure. Using the kitchen outbuilding as cover, du Plessis reached a ground-floor window to the left of the servant's entrance. He smashed it and tried to climb in. Perched on the window sill, he found himself face to face with a pistol-wielding British officer who demanded his surrender. At that moment, a British soldier burst into the room and fired at du Plessis but hit the officer by mistake. After this close call, the Frenchman decided to retreat. With numerous American soldiers looking on, he refused to run for it. He later claimed that he retired at a walk, which he managed to do without being shot, though Laurens was slightly wounded in the shoulder. Two of Major General John Sullivan's aides, Captains John White and Edward Sherburne were killed while unsuccessfully trying to carry out this dangerous mission.
Later that month, George Washington sent du Plessis to Fort Mercer to take command of the garrison's artillery and also to oversee its defenses. When he reported to Colonel Christopher Greene on 11 October, he found a sprawling fortress that was long and wide. The works were far too extensive for the 250 defenders and 14 cannons. Du Plessis immediately constructed a new wall that bisected the old works, effectively abandoning a large part of the fort in order to concentrate the defenses in a smaller area. Since fruit trees made excellent abatis, James Whitall's nearby orchard was entirely cut down for the purpose. For his part, Greene ordered every available man to help the French engineer improve the fort's defenses.