Photian schism

The Photian Schism was a four-year (863–867) schism between the episcopal sees of Rome and Constantinople.

At issue was the papal claim to jurisdiction in the East, not accusations of heresy. The schism arose largely as a struggle for ecclesiastical control of the southern Balkans and because of a personality clash between the heads of the two sees, both of whom were elected in the year 858 and both of whose reigns ended in 867, by death in the case of the Pope, by the first of two depositions for the Patriarch. The Photian Schism thus differed from what occurred in the 11th century, when the pope's authority as a first among equals was challenged on the grounds of having lost that authority through heresy.