He was ordered by Gen. Guy Carleton to delay the American advance on Montreal, and Quebec. He was in command of 662 men of the 26th Regiment, engineers, Canadians, and Indians. They held Fort St. Jean, at Saint-Jean-sur-Richelieu, Quebec, in 1775 when it came under siege by American General Richard Montgomery, and resisted multiple attacks by troops under command of Montgomery and Philip Schuyler. His troops held the fort in hopes of being rescued by reinforcements for two months before surrendering on the third of November 1775.