Anne-Louis de Tousard was born in Paris, France, on March 12, 1749, the second son of French general Charles Germain de Tousard and his wife, Antoinette de Poitevin de la Croix. A 1765 graduate of the artillery school in Strasbourg, he was commissioned a second lieutenant in the French Royal Artillery Corps. He resigned his commission in 1776 in order to enter into the American Revolution, and with the assistance of Caron de Beaumarchais, traveled to America where he received a position on Washington's staff in June 1777. He served with distinction during the War, first with Philippe Tronson De Coudray and later as an aide-de-camp to Lafayette. He lost his right arm in an attempt to seize cannon during the Battle of Rhode Island on August 29, 1778, and for his war time service, was granted a lieutenant colonelcy and a life pension by Congress.
In 1784, Tousard was commissioned lieutenant colonel in the Regiment du Cap, an elite French unit stationed in Saint Domingue (present-day Haiti). He soon purchased land for coffee cultivation in the districts of Vallière and Jérémie. On February 19, 1788, he married Marie-Reine St. Martin, née Joubert, (ca. 1765-1794), the widow of a Saint-Domingue planter. She had a young daughter, Martine (b. 1785). Together, Louis and Marie had two children: Caroline (b. 1788) and Laurette (b. 1791). Louis frequently traveled around the island with the regiment, leaving Marie to manage the plantations and slaves on her own. During the early stages of the Haitian Revolution, he led soldiers in the suppression of the slave rebellion in engagements at Port-Margot (September 1791) and Fort-Dauphin (November 1791). In 1792, Tousard protested the imprisonment of his commanding officer and was himself arrested and imprisoned in France in December 1792.
Tousard remained there until February 1793, when American diplomats negotiated for his release; he aided his case through the publication of a defense of his actions in Haiti, entitled Justification of Lewis Tousard. In April of that year, he settled with his wife and children in Wilmington, Delaware, where Marie died in July 1794. The next year, he married Anna Maria Geddes (b. 1775). Tousard soon secured a commission as Major of the 2nd Artillery, and helped plan and supervise the construction of fortifications at Fort Mifflin, Pennsylvania, and at West Point, New York. After the 2nd Artillery was disbanded in 1802, Tousard returned to civilian life and in 1805, was appointed French vice-consul in Philadelphia, later serving as consul at New Orleans (1811-1815). He returned to Paris a year before his death on March 4, 1817.