It was by diplomacy that John hoped to parry the attack which he knew he could not repel by force. Early in the year he had complained to the Pope of the long course of insult and aggression pursued towards him by Philip, and begged Innocent to interfere in his behalf.[412] Thereupon Philip, in his turn, sent messengers and letters to the Pope, giving his own version of his relations with John, and endeavouring to justify his own conduct.[413] On May 26 Innocent announced to both kings that he was about to despatch the abbots of Casamario, Trois-Fontaines and Dun as commissioners to arbitrate upon the matters in dispute between them.[414] These envoys seem to have been delayed on their journey; and when they reached France they, for some time, found it impossible to ascertain whether Philip would or would not accept their arbitration. When at last he met them in council at Mantes on August 26, he told them bluntly that he “was not bound to take his orders from the Apostolic See as to his rights over a fief and a vassal of his own, and that the matter in dispute between the two kings was no business of the Pope’s.”[415] John meanwhile had, on August 11, suddenly quitted his passive attitude and laid siege to Alençon; but he retired on Philip’s approach four days later. An attempt which he made to regain Brezolles was equally ineffectual.[416] Philip, on the other hand, was now resolved to bring the war to a crisis. It was probably straight from the council at Mantes that he marched to the siege of Château-Gaillard.[417]