A year later the other branch of Stephen's family came into a new relationship to the politics of France and England. At the beginning of October, 1160, Louis's second wife died, leaving him still without a male heir. Without waiting till the end of any period of mourning, within a fortnight, he married the daughter of Stephen's brother, Theobald of Blois, sister of the counts Henry of Champagne and Theobald of Blois, who were already betrothed to the two daughters of his marriage with Eleanor. This opened for the house of Blois a new prospect of influence and gain, and for the king of England of trouble which was in part fulfilled. Henry saw the probable results, and at once responded with an effort to improve his frontier defences. The marriage of the young Henry and Margaret of France was immediately celebrated, though the elder of the two was still a mere infant. This marriage gave Henry the right to take possession of the Norman Vexin and its strong castles, and this he did. The war which threatened for a moment did not break out, but there was much fortifying of castles on both sides of the frontier. It is said that the suggestion of this defensive move came from Thomas Becket. However this may be, Thomas was now near the end of his career of service to the state as chancellor, and was about to enter a field which promised even greater usefulness and wider possibilities of service. Archbishop Theobald of Canterbury died on April 18, 1161. For some months the king gave no sign of his intentions as to his successor. Then he declared his purpose. Thomas, the chancellor, was about to cross to England to carry out another plan of Henry's. The barons were to be asked to swear fealty to the young Henry as the direct heir to the crown. Born in February, 1155, Henry was in his eighth year when this ceremony was performed. Some little time before he had been committed by his father to the chancellor to be trained in his courtly and brilliant household, and there he became deeply attached to his father's future enemy. The swearing of fealty to the heir, to which the barons were now accustomed, was performed without objection, Thomas himself setting the example by first taking the oath.