On the death of Robert, his son William was about eight years old; moreover, of illegitimate birth, his mother being the daughter of a tanner at Falaise. But Robert, before his departure, had caused his nobles to swear allegiance to William, and the law of hereditary descent was far more strictly regarded in France than in England. These facts, joined to the consideration that possible successors of the line of Rollo were not easily to be found, caused William's accession to be undisputed. Nevertheless, the period of his minority was one of much confusion, during which the boy-duke's life was in perpetual danger, and his position was the more precarious because the King of the French began to show signs of animosity towards the great semi-independent state to the north of his dominions. In 1047 William began to act for himself, and when an attempt was made by the nobles to wrest the western part of his dominions from him, he overthrew the rebels, with the grudgingly offered aid of Henry of France, at Val-ès-Dunes. After this crushing triumph, his power was secure. He surrounded himself with a splendid nobility, of whom William Fitz-Osbern and Odo, Bishop of Bayeux, his two half-brothers by his mother's marriage with Baldwin of Conteville, and Robert of Mortain, were to make themselves feared on the other side of the channel. The Church was munificently rewarded for its support, and among his most magnificent buildings was the Abbé aux Hommes at Caen. Not only did he recover all the dominions that the Norman dukes had ever held, but he twice defeated the French king, Henry, when he invaded his dominions, and in 1063 made his great Continental acquisition in the conquest of Maine. Despite the Papal inhibition, he took to wife Matilda, the daughter of Count Baldwin of Flanders, in 1052, and endured the ban without much inconvenience until 1060. His visit to England, and the claim, worthless though it was, that he built upon it, have already been mentioned (_see p._ 70). In the last years of the reign of the Confessor (the exact date is unknown) the hazard of fortune placed his rival, Harold, in his power for the time being, and he made excellent use of the opportunity. [Illustration: PEVENSEY CASTLE.] One day Harold, while sailing in the channel, was driven by tempest on the territory of Guy, Count of Ponthieu, who, being informed of his quality, immediately detained him prisoner, and demanded an exorbitant sum for his ransom. Harold found means to convey intelligence of his situation to the Duke of Normandy; and represented that he had met with extremely harsh treatment from the mercenary disposition of the Count of Ponthieu, who was William's vassal.