Jacques Léonard Muller (11 December 1749 – 1 October 1824) commanded the Army of the Western Pyrenees and the Army of the Rhine during the French Revolutionary Wars. He was a product of the French Royal Army which he joined in 1765. He became a captain in 1791 and soon formed a unit from the disbanded Swiss regiments of the old army. He fought at Jemappes and then transferred to the War Office. Promoted to general officer in July 1793 he was appointed chief of staff to the Army of the Pyrenees. In October 1793 he assumed command of that army despite being outranked by ten other generals. He immediately set about providing a good organization for his motley host. A major Spanish attack on the Sans Culottes Camp was repulsed in February 1794.