Pope Leo IX.
Backs the Normans against the Byzantines in Southern Italy, contributing to the east-west Church schism. 1054
A Supernova that now forms the Crab Nebula is observed in the East. July 4, 1054
It is visible for 22 months.
Legates sent by Pope Leo IX appear at the Church of Hagia Sophia, at the beginning of services, and declare that all of their endeavors to re-establish union have been rejected by Michael Cerularius, Patriarch of Constantinople.
The legates lay the papal bull of excommunication on the high altar and leave the church. July 16, 1054
Michael Cerularius rejects the “filioque” clause.
Final and complete separation of the Christian Church into two distinct parts: the Western Roman Catholic Church at Rome and the Eastern or Greek Church at Constantinople.
Reciprocal excommunication of Roman and Greek churches is announced.
Leo IX is Pope, Michael Cerularius is the Patriarch of Constantinople.
Henry I of France, Geoffrey of Anjou, and Theobald of Blois invade Normandy. 1054
William I, the Conqueror (b.1027-d.1087) successfully repels the combined invasion of their armies at Mortemer.
Council at Sens. 1054
Condemns Berengarius of Tours in the controversy over the Real
Presence or the transubstantiation of the Eucharist.
Robert Guiscard (Norman) takes Benevento. 1054
Death of Pope Leo IX. 1054