In 1754, he accompanied his father to America, and served as an ensign in the 48th Regiment of Foot on the expedition to Fort Duquesne, also performing as a supernumerary engineer. In the defeat that followed he was wounded, but survived to learn of his promotion to lieutenant days before the battle. He remained in America, serving along the Mohawk River and at Fort Edward, then accompanying British forces to Halifax. In 1758, he was commissioned a practicing engineer in the Corps of Engineers, and as such was present at the siege of Louisbourg, and later, at that of Quebec, there drawing one of the last known portraits of General Wolfe, who died in the deciding battle.