1054: limited excommunications and East–West estrangement
About this date: A limited exchange of excommunications amid a longer estrangement; not a single-day origin story for the schism.
Papal legates excommunicated Patriarch Michael Keroularios and his supporters; the Constantinopolitan synod condemned the legates. The event became an emblem of the East–West schism, but did not amount to reciprocal excommunication of the entire Eastern and Western Churches or create their division in one day.
People
- Michael Keroularios
- Cardinal Humbert