Leo IX
Pope in whose name the legates of 1054 went to Constantinople. A letter of 1053 under his name set out the claims of the Roman see against the patriarch. He died at Rome three months before the excommunication.
The letter sent in Leo’s name to Michael Cerularius insists that the Roman church is the head of all the churches and is judged by none, and cites the Donation of Constantine as proof of its privileges (Leo IX, Letter to Michael Cerularius (In terra pax) 10–14; 20 (pp. 70–74, 76)). Hermann of Reichenau, a contemporary, records that the pope was detained for some time at Benevento, came back to Rome sick as Easter approached and died there in April 1054 (Hermann of Reichenau, Chronicle, years 1053–1054).
The legates nevertheless acted in July on the authority of the Roman see, citing the letters Pope Leo had sent to Michael (Bull of excommunication (1054)), and the patriarch of Antioch, writing to Constantinople afterwards, advised waiting until a new pope was chosen (Peter of Antioch, Letter to Michael Cerularius 19). See the Schism of 1054.
In the timeline
- 16 July 1054, firm dateThe Schism of 1054
Legates of the Roman see excommunicate the patriarch of Constantinople in Hagia Sophia, and his synod anathematizes them in return. The sentences name persons, not churches, but later ages take the day as the breach between East and West.