Much more of the last ten years of William's life was spent in Normandy than in England. Revolts of unruly barons, attacks on border towns or castles, disputes with the king of France, were constantly occupying him with vexatious details, though with nothing of serious import. Most vexatious of all was the conduct of his son Robert. With the eldest son of William opens in English history a long line of the sons and brothers of kings, in a few cases of kings themselves, who are gifted with popular qualities, who make friends easily, but who are weak in character, who cannot control men or refuse favours, passionate and selfish, hardly strong enough to be violently wicked as others of the line are, but causes of constant evil to themselves and their friends, and sometimes to the state. And with him opens also the long series of quarrels in the royal family, of which the French kings were quick to take advantage, and from which they were in the end to gain so much. The ground of Robert's rebellion was the common one of dissatisfaction with his position and his father's refusal to part with any of his power in his favour. Robert was not able to excite any real insurrection in Normandy, but with the aid of his friends and of the French king he maintained a border war for some time, and defended castles with success against the king. He is said even, in one encounter, to have wounded and been on the point of slaying his father. For some time he wandered in exile in the Rhine valley, supported by gifts sent him by his mother, in spite of the prohibition of her husband. Once he was reconciled with his father, only to begin his rebellion again. When the end came, William left him Normandy, but people thought at least that he did it unwillingly, foreseeing the evil which his character was likely to bring on any land over which he ruled.