In modern historical writing the schism of 1054 dominates the end of Monomachos’ reign. It had little impact at the time, but it was important for the future, because it underlined the unbridgeable gulf that was developing between Byzantium and the west. The background to the schism was paradoxically an alliance between the Byzantine emperor and Pope Leo IX (1049–54). It was directed against the Normans and had been engineered by Argyros. There was an assumption on the part of the papacy that this alliance would promote its claims to jurisdiction over the church in Byzantine Italy. In 1053 the papal forces made contact with the Normans near Civitate. They were expecting to link up with a Byzantine army under Argyros, but it failed to appear. TheNormans trounced the papal army and captured Leo IX. This did not prevent him from despatching a delegation to Constantinople in the autumn of 1053 to renew the Byzantine alliance. It was headed by Humbert, cardinal priest of Silva Candida, chief ideologue of the papal reform movement and Leo IX’s trusted adviser. By the time the papal legation reached Constantinople the pope was dead, but its members carried on regardless, acting as though their commissions were still valid. Constantine IX Monomachos gave them much encouragement; the alliance with the papacy remained vital for his Italian policy. CardinalHumbert followed the instructions he had received fromLeo IX. The alliance was to be cemented by a regularisation of relations between the two churches, which had not been in communion for nearly half a century. The discussion revolved around the Latin use of unleavened bread – azymes – in the communion service. The patriarch of the day,Michael I Keroularios (1043–58), had earlier condemned it as a Jewish practice and argued that the Byzantine use of leavened bread had the support of the gospels. Leo IX had taken exception to this and wanted the question resolved. Cardinal Humbert tried to carry out his wishes, but it was difficult because Keroularios refused to acknowledge his presence. Humbert treated this as contumacy. On 16 July 1054 he entered St Sophia with the other papal legates and put on the altar a bull of excommunication directed at Michael Keroularios. The patriarch in his turn placed Humbert and the rest of the papal delegation under anathema. It confirmed an already existing state of schism between the two churches. What stance did Constantine IX Monomachos adopt? From the outset he worked for an accord between the two churches. The papal legates came under his protection. He organised two debates between Humbert and a representative of the orthodox church, designed to clarify all the issues separating the two churches. They were conducted in an irenic fashion. Monomachos was as frustrated as the papal legates by Keroularios’ lack of cooperation. This does not mean that he would have encouraged Humbert to excommunicate the patriarch. The legates’ hasty departure from the City suggests that Monomachos had not approved their action. Michael Keroularios insisted that the papal legates should be brought back to Constantinople. The emperor demurred, but the patriarch used popular indignation to get his way. The legates were reprimanded, but punishment was reserved for the interpreters and members of Argyros’ immediate family, who happened to be resident in the capital. Michael Keroularios blamed the incident on Argyros, who was a personal enemy. He accused him of deliberately misinforming the papacy. By singling out Argyros as the main culprit, Keroularios played down the religious issues. There were still hopes that the differences between the two churches might be resolved, or so it seemed to one of the legates, Frederick of Lorraine, who in 1057 became Pope Stephen IX. He almost immediately despatched a delegation to Constantinople to repair the damage, but it never reached its destination because he died soon after it set out. Other counsels prevailed at Rome. In 1059 the new pope Nicholas II (1058–61) turned to the Normans for support. By this time the events of 1054 had forced a reassessment of papal interests. These were now seen to be better served by an alliance with the Normans rather than with the Byzantines. It was a momentous change which profoundly affected western relations with Byzantium.