Territorial evolution of France face up to the formidable challenge with which they were presented. The Duke of Normandy William the Conqueror became King of England in 1066 through his victory at Hastings over the Saxons. On the extinction of his male line of descent, his heir was the Duke of Anjou, Henry Plantagenet, grandson by his mother of Henry I of England. Two months before he ascended to the English throne, as Henry II, he married Eleanor, Duchess of Aquitaine, the richest heiress in the French kingdom and ex-wife of the King of France. The kings of France nevertheless, held some trump cards:
William of Jumièges "De moribus et actis primorum Normannorum ducum", between c. 996 and c. 1015. This work was commissioned by Duke Richard I, and "was renewed by his half-brother, Count Rodulf of Ivry, and his son Duke Richard II (996-1026)... Dudo's work was taken up by William of Jumièges in the 1050s, who revised, abbreviated and updated his "De moribus" and added an account of the reigns of Dukes Richard II, Richard III (1026-7), Robert I (1027-35), and William II [William the Conqueror]." He finished this by 1060 but added to it later when William the Conqueror had become king of England,