Henry I (of France) (circa 1008-1060), king of France (1031-1060), son of King Robert II and grandson of Hugh Capet, founder of the Capetian dynasty. From the beginning of his reign he was occupied with putting down rebellions led by members of his family and other French nobles. Between 1035 and 1047 he assisted his nephew William, duke of Normandy, later William the Conqueror, king of England, in establishing William's authority over rebellious Norman nobles. Henry later grew jealous of William's power and waged unsuccessful war against him in 1054 and 1058. Henry was succeeded by his son Philip I.