As a soldier in the French troupes de la marine, Belestre fought against British and American colonial troops for 30 years, from Nova Scotia to the Mississippi River valley. Belestre became famous during the wars between France and Great Britain, serving in the North American theater of the Seven Years' War, also known as the French and Indian War (1754–63). He was one of the last officers of New France to surrender to British troops. In 1758, Belestre became the thirteenth and last official French Commandant of Fort Ponchartrain (Fort Detroit). His term ended in 1760 with the end of French rule in Detroit, after which he was sent to England. He returned to Quebec under British rule, and joined the British troops which defended Fort Saint Jean from American colonial forces in 1775. He became a colonel in the British Army before his death.