East-West Schism
However instances of open division on doctrinal questions as well as daily matters had occurred long before the Great Schism of 1054. Leading up to the schism, Pope Leo IX (1002-1054) sent forth a party led by Cardinal Humbert of Silva Candida to talk through the obvious problems between the papacy and Constantinople. Michael Cerularius, the Patriarch of Constantinople, rejected the claims put forward by the papal committee. Those from the western side of the church accused Constantinople of having altered the Nicene Creed, and those from the eastern side accused the western church of altering the creed. This in turn led to Cardinal Humbert putting forward a Bull of Excommunication against Michael Cerularius on the altar of the Hagia Sophia, and the Great Schism became official.