The Great Schism Splits Rome and Constantinople
A furious papal legate lays a bull of excommunication on the altar of Hagia Sophia
Quick facts
- Date
- July 16, 1054 CE
- Papal legate
- Cardinal Humbert of Silva Candida
- Patriarch
- Michael Cerularius
- Anathemas lifted
- 1965, by Pope Paul VI and Patriarch Athenagoras I
What happened
Centuries of theological and political friction between the Latin West and Greek East, over questions including the filioque addition to the Nicene Creed and the use of unleavened bread in the Eucharist, came to a head after Norman conquerors in southern Italy suppressed Greek church practices there. Patriarch Michael Cerularius of Constantinople retaliated by pressuring Latin churches in his own city to adopt Greek customs, prompting Pope Leo IX to send a delegation led by Cardinal Humbert of Silva Candida. After a cold reception, Humbert strode into Hagia Sophia during a service on July 16, 1054 CE and placed a bull of excommunication against Cerularius on the altar; the patriarch responded within days by excommunicating Humbert and the other legates in turn.
Why it matters
Modern historians agree no single event caused a clean, immediate break, and relations between individual eastern and western churches remained workable in places for some time afterward, but this mutual excommunication became the symbolic starting point historians call the Great Schism, a division between the Catholic and Orthodox churches that the two sides did not formally lift until 1965.
How we know
The events of July 1054 CE are recorded in the Orthodox Church in America's own institutional history of the schism and corroborated by independent Western and Byzantine accounts of Humbert's mission and Cerularius's response.
Sources
- Christian History Institute. 1054 The East-West Schism · Reputable sourcechristianhistoryinstitute.org · The domain "christianhistoryinstitute.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- Orthodox Church in America. The Great Schism · Primary source (author-declared)oca.org · Cited as a "primary" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
See something wrong? . Corrections with a source get fixed fastest.
Related timelines
- The Byzantine Empire → · The Byzantine Empire timeline covers the Great Schism from Constantinople's side, including the political tensions with the Normans that set it off.