Most of the direct causes of the Great Schism, however, are far less grandiose than the famous ''filioque''. The relations between the papacy and the Byzantine court were good in the years leading up to [[1054]]. The emperor [[Constantine IX]] and the Pope [[Pope Leo IX]] were allied through the mediation of the [[Lombards|Lombard]] [[catepan of Italy]], [[Argyrus]], who had spent years in Constantinople, originally as a political prisoner. Leo and Argyrus led armies against the ravaging [[Normans]], but the papal forces were defeated at the [[Battle of Civitate]] in [[1053]], which resulted in the pope being imprisoned at [[Benevento]], where he took it upon himself to learn [[Greek language|Greek]]. Argyrus had not arrived at Civitate and his absence caused a rift in papal-imperial relations.

Although he was hot-headed, Michael was convinced, probably by the Emperor and the bishop of Trani, to cool the debate and prevent the impending breach. However, Humbert and the pope made no concessions and the former was sent with legatine powers to the imperial capital to solve the questions raised once and for all. Humbert, Pope [[Pope Stephen IX|Frederick of Lorraine|Stephen IX]], and Peter, [[Archbishop of Amalfi]] set out in early spring and arrived in April [[1054]]. Their welcome was not to their liking, however, and they stormed out of the palace, leaving the papal response with Michael, whose anger exceeded even theirs. The seals on the letter had been tampered with and the legates had published, in Greek, an earlier, far less civil, draft of the letter for the entire populace to read. The patriarch determined that the legates were worse than mere barbarous Westerners, they were liars and crooks. He refused to recognise their authority or, practically, their existence.<ref>[[John Julius Norwich|Norwich, John Julius]]. ''The Normans in the South 1016-1130''. ([[1967]]) pg 102.</ref>

When Pope Leo died on [[April 19]],[[1054]], the legates' authority legally ceased, but they did not seem to notice.<ref>Norwich, John Julius ''Byzantium, The Apogee''. New York: Alfred A. Knoff (1992) p.320</ref> The patriarch's refusal to address the issues at hand drove the legatine mission to extremes: on [[July 16]], the three legates entered the church of the [[Hagia Sophia (Constantinople)|Hagia Sophia]] during the divine liturgy on a Saturday afternoon and placed a [[Papal Bull]] papal bull of [[Excommunicationexcommunication]] ([[1054]]) on the altar. The legates left for Rome two days later, leaving behind a city near riots. The patriarch had the immense support of the people against the Emperor, who had supported the legates to his own detriment, and Argyrus, who was seen still as a papal ally. To assuage popular anger, Argyrus' family in Constantinople was arrested, the bull was burnt, and the legates were [[anathema]]tised&mdash;the Great Schism had begun.

''The New Catholic Encyclopedia '' says, "The consummation of the schism is generally dated from the year [[1054]], when this unfortunate sequence of events took place. This conclusion, however, is not correct, because in the bull composed by Humbert, only Patriarch Michael I was excommunicated. The validity of the bull is questioned because Pope Leo IX was already dead at that time. On the other side, the Byzantine synod excommunicated only the legates.

It should be noted that the bull of excommunication issued against Patriarch Michael stated as one of its reasons for the excommunication the Eastern Church's deletion of the word "filioque" from the original Nicene Creed. It is now common knowledge that the Eastern Church did not delete anything, it was the Western Church that added this word to the [[Nicene creed#The original Nicene Creed of 325|original Nicene -Constantinopolitan Creed]].