Jacques Charles de Fitz-James, 5th Duke of Fitz-James was a French-born nobleman who was a grandson of James FitzJames, 1st Duke of Berwick, himself an illegitimate son of King James II and VII by Arabella Churchill, herself a sister of the 1st Duke of Marlborough while his mother was a daughter of Charles Auguste de Goÿon, Count of Gacé, Marshal of France During the French Revolution, Fitz-James was also part of the Armée des Émigrés. Wikipedia