We need not enter into the details of the long struggle between Canterbury and York. The archbishopric of Canterbury was vacant for five years after the death of Anselm; its revenues went to support the various undertakings of the king. In April, 1114, Ralph of Escures, Bishop of Rochester, was chosen Anselm's successor. The archbishopric of York had been vacant only a few months, when it was filled, later in the summer, by the appointment of Thurstan, one of the king's chaplains. The question of the obligation of the recently elected Archbishop of York to bind himself to obedience to the primate of Britain, whether settled as a principle or as a special case, by an English council or by the king or under papal authority, arose anew with every new appointment. In the period which follows the appointment of Thurstan, a new element of interest was added to the dispute by the more deliberate policy of the pope to make use of it to gain a footing for his authority in England, and to weaken the unity and independence of the English Church. This attempt led to a natural alliance of parties, in which, while the issue was at bottom really the same, the lines of the earlier investiture conflict were somewhat rearranged. The pope supported the claim of York, while the king defended the right of Canterbury as bound up with his own. At an important meeting of the great council at Salisbury, in March, 1116, the king forced upon Thurstan the alternative of submission to Canterbury or resignation. The barons and prelates of the realm had been brought together to make formal recognition of the right to the succession of Henry's son William, now fourteen years of age. Already in the previous summer this had been done in Normandy, the barons doing homage and swearing fealty to the prince. Now the English barons followed the example, and, by the same ceremony, the strongest tie known to the feudal world, bound themselves to accept the son as their lord on the death of his father. The prelates, for their part, took oath that if they should survive Henry, they would recognize William as king, and then do homage to him in good faith. The incident is interesting less as an example of this characteristic feudal method of securing the succession, for this had been employed since the Conquest both in Normandy and in England, than because we are told that on this occasion the oath was demanded, not merely of all tenants in chief, but of all inferior vassals. If this statement may be accepted, and there is no reason to doubt it, we may conclude that the practice established by the Conqueror at an earlier Salisbury assembly had been continued by his sons. This was a moment when Henry was justified in expressing his will, even on a matter of Church government, in peremptory command, and when no one was likely to offer resistance. Thurstan chose to surrender the archbishopric, and promised to make no attempt to recover it; but