Michel was brought up at the Jesuit College in Quebec before becoming a cadet with the colonial troupes de la marine, breaking family tradition by being the first not to preside over the Sovereign Council of New France. As second ensign he served in the Defence of the Acadians of 1746-47 gaining a reputation as "a capable and courageous officer". In 1747, Lotbinière married Louise-Madeleine Chaussegros de Léry, the daughter of Gaspard-Joseph Chaussegros de Léry (1682-1756), chief engineer of New France, and his wife Marie-Renée Legardeur de Beauvais. In 1749, his relation, the Commandant General of New France, Roland-Michel Barrin de La Galissonière, promoted him to ensign and entrusted him to lead a reconnaissance mission into the region between Montreal and Michilimackinac.