The son of
John Stewart of Darnley and Elizabeth, daughter of
Donnchadh, Earl of Lennox, Darnley accompanied his father and brothers to fight in
France. Following his father's death at the
Battle of the Herrings in 1429 during the
Siege of Orléans, Darnley inherited his father's title of the Lordship of
Concressault, but not the
County of Évreux, nor the Lordship of Aubigny. He also inherited the title of Constable of the Scottish Army in France, and the chieftaincy of the
Stewarts of Darnley. By 1437, he had resigned his French territories to his younger brother,
Sir John Stewart and returned to Scotland. He became involved in a
blood feud with the
Boyd family of
Dean Castle. Darnley was killed in 1439 by Sir Thomas Boyd of
Kilmarnock, his death was avenged later that summer by his youngest brother Alexander Stewart at the
Battle of Craignaught Hill. ==Marriage and issue==