In 1775 he became involved in the American invasion of Quebec early in the American Revolutionary War, and served with the Continental Army, in the 1775 Battle of Quebec. He went on to lead his own regiment, (the 2nd Canadian, also known as "Congress' Own") throughout the war, seeing action in the 1777 Philadelphia campaign and at Yorktown in 1781. He was frequently involved in litigation, both military and civil, and constantly petitioned Congress for compensation of losses and expenses incurred due to the war. He supported similar efforts by men from his regiment who were unable to return to Quebec because of their support for the American war effort.