Among the circumstances that produced the failure of this crusade, history must not forget the protracted vacancy of the papal throne, during which no voice was raised to animate the Crusaders, in which there was no authority powerful enough, particularly after the death of St. Louis, to direct their enterprise. After a lapse of two years, however, the conclave chose a successor of St. Peter; and, fortunately for the eastern Christians, the suffrages fell upon Thibault, archdeacon of Liege, who had followed the Frisons into Asia, and whom the intelligence of his elevation found still in Palestine. The Christians of Syria had reason to hope that the new pontiff, for so long a time a witness of their perils and their miseries, would not fail to employ all his power to succour them. Thibault gave them an assurance of it before he quitted Ptolemaïs, and in a discourse which he addressed to the assembled people, he took for his text this verse of the hundred and thirty-seventh Psalm: “If I forget thee, O Jerusalem, may I myself be forgotten among men!” The patriarch of Jerusalem, and the grand masters of the Temple and the Hospital accompanied Gregory X. into the West. On his return, the pontiff applied himself at once to the re-establishment of peace in Italy and Germany. He engaged the princes, particularly the king of France, to unite their efforts in assisting the Holy Land. Philip contented himself with sending a few troops into the East, and with advancing thirty-six thousand silver marks to the Pope, for which sum he held as security all the possessions of the Templars in his kingdom. Pisa, Genoa, and Marseilles furnished several galleys, and five hundred warriors were embarked for Ptolemaïs, at the expense of the sovereign pontiff. This assistance was far from answering the hopes or the wants of the Christian colonies. Gregory resolved to interest all Christendom in his project, and for that purpose convoked a council at Lyons, in 1274. This council was much more numerous and more solemn than that which Innocent IV. had assembled thirty years before in the same city. At this were present the patriarchs of Jerusalem and Constantinople, more than a thousand bishops and archbishops, the envoys of the emperors of the East and of the West, those of the kings of France and Cyprus, and of all the princes of Europe and beyond the seas. In this numerous assembly, no persons attracted so much attention as the Tartar princes and ambassadors, sent by the powerful head of the Moguls, to form an alliance with the Christians against the Mussulmans; several of these Tartar princes received baptism from the hands of the Pope, and Christians who were witnesses of this ceremony saw in it an assured pledge of the Divine promises.