His next task was to attach the other princes of Wales to him, now that the Lord Rees and Owen Cyveiliog were dead. To begin with, he had to deal with the astute Gwenwynwyn, the son of Owen Cyveiliog; and he had to be forced to submit. He then turned to the many sons and grandsons of the Lord Rees—Maelgwn and Rees the Hoarse especially. They called John, King of England, into Wales; but they soon found that Llywelyn was a better master than John and his barons. Gradually Llywelyn established a council of chiefs—partly a board of conciliation, and partly an executive body. It was nothing new; but it was a striking picture of the way in which Llywelyn meant to join the princes into one organised political body. His third task was to begin to unite Norman barons and Welsh chiefs under his own rule. He had to begin in the old way, by using force; and Ranulph of Chester and the Clares trembled for the safety of their castles. He then offered political alliance; and some of the Norman families of the greatest importance in the reign of John—the Earl of Chester, the family of Braose, and the Marshalls of Pembroke—became his allies. His other step was to unite Welsh and Norman families by marriage. He himself married a daughter of King John, and he gave his own daughters in marriage to a Braose and a Mortimer. It is through the dark-haired Gladys, who married Ralph Mortimer, that the kings of England can trace their descent from the House of Cunedda. Llywelyn’s last great task was to make relations between England and Wales relations of peace and amity. During his long reign, he saw three kings on the throne of England—the crusader Richard, the able John, and the worthless and mean Henry III. It was with John that he had most to do, the king whose originality and vices have puzzled and shocked so many historians. John helped him to crush Gwenwynwyn, then helped the jealous Welsh princes to check the growth of his power. Llywelyn saw that it was his policy, as long as John was alive, to join the English barons. They were then trying to force Magna Carta upon the King, that great document which prevented John from interfering with the privileges of his barons. In that document John promises, in three clauses, that he will observe the rights of Welshmen and the law of Wales.