Robert I, byname ROBERT The MAGNIFICENT, or The DEVIL, French ROBERT le MAGNIFIQUE, or le DIABLE (d. July 1035, Nicaea), duke of Normandy (1027-35), the younger son of Richard II of Normandy and the father, by his mistress Arlette, of William the Conqueror of England. On the death of his father (1026/27), Robert contested the duchy with his elder brother Richard III, legally the heir, until the latter's opportune death a few years later. A strong ruler, Robert succeeded in exacting the obedience of his vassals. On the death of Robert II the Pious, king of France (1031), a crisis arose over the succession to the French throne. The Duke gave his support to Henry I against the party favouring his younger brother; in reward for his services he demanded and received the Vexin FranAais, a territory not far north of Paris. A patron of the monastic reform movement, he died while returning from a pilgrimage to Jerusalem. [Encyclopaedia Britannica CD '97]