On this day October 5, 869
The Fourth Council of Constantinople, the eighth Catholic Ecumenical Council, was convened to discuss the patriarchate of Photios I of Constantinople.
The Council met in 10 sessions from October 869 to February 870 and issued 27 canons. The council was called by Emperor Basil I the Macedonian and Pope Adrian II.
It deposed Photios, a layman who had been appointed as Patriarch of Constantinople, and reinstated his predecessor Ignatius.
A later council, the Greek Fourth Council of Constantinople, was held after Photios had been reinstated on order of the Emperor, and it annulled the earlier one.
Today, the Roman Catholic Church recognizes the council in 869-870 as “Constantinople IV”, while the Eastern Orthodox Churches recognize the councils in 879-880 as “Constantinople IV” and revere Photios as a saint. At the time that these councils were being held, this division was not yet clear.
These two councils represent a break between East and West. The previous seven ecumenical councils are recognized as ecumenical and authoritative by both Greek-literate Eastern Christians and Latin-literate Western Christians. This division led eventually to the East-West Schism of 1054.
Photios I Φώτιος and known by the Eastern Orthodox churches as St. Photios the Great, was Patriarch of Constantinople from 858 to 867 and from 877 to 886. Photios is widely regarded as the most powerful and influential Patriarch of Constantinople since John Chrysostom, and as the most important intellectual of his time, “the leading light of the ninth-century renaissance”.
He was a central figure in both the conversion of the Slavs to Christianity and the estrangement of the Eastern Orthodox churches from the Catholic Church. Photios is recognized as a saint by the Eastern Orthodox churches.