Gregory X. had decreed the convocation of a Council at Lyons in 1274 in order to promote a crusade against the infidels; and reaching Florence on June 18, 1273, suspended his journey for awhile for the purpose, as he said, of re-establishing the general peace. He arrived with his whole train of cardinals and prelates, accompanied by the Emperor of Byzantium, Baldwin II., who came to ask Christian aid against the Infidel, and escorted by Charles of Anjou, whose sense of the honour due to the pontiff, so he said, forbade leaving him alone in Florence. And as the Pope found the city to his liking, he decided to spend the whole summer there. The 2nd of July was the day fixed for the solemn reconciliation of the Guelphs and Ghibellines, and the syndics, or leaders, of either party were gathered in the town. On the waste of dry sand in the bed of the Arno by the Ponte alle Grazie wooden platforms had been erected, and here the Pope, the Emperor Baldwin, and Charles of Anjou were seated in state. The oath of peace was sworn in the presence of a great throng of spectators; the syndics exchanged kisses, and the Pope gave his benediction, threatening excommunication on all who should dare to break the peace. Both sides gave hostages and yielded castles as pledges of faith, and everything seemed to be arranged in accordance with the benevolent intentions of the Pope. The Holy Father was lodged in the palace of his bankers, the Mozzi, Baldwin in that of the bishop, while Charles occupied several houses in the Frescobaldi gardens. There was now time to enjoy life in Florence before the return of the banished Ghibellines and the festivals to be given in their honour. But suddenly it was learnt that the Ghibelline syndics, instead of carrying out the concluding terms of the peace, had hastily fled from Florence. And the reason alleged for this was, that the king's vicar had sent them an intimation that unless they left the city without delay, he would have them all cut to pieces at the request of the Guelph nobles. Thereupon the Pope instantly set out for the Mugello, much enraged not only with the king, but even more with the Florentines for their indifference to the whole farce, and he punished their violation of the oath by pronouncing an interdict on the city.