 Unlike his father, he immediately recognised the importance of working with the British and he therefore adapted himself to the circumstances in which he found himself.After the American invasion of Montreal in 1775, he was one of the first Canadian seigneurs to offer his services to the Governor Guy Carleton, 1st Baron Dorchester.He helped to defend Fort St Johns (later Saint-Jean-sur-Richelieu) against the Americans, but was captured and taken prisoner by them and removed to Albany, New York.