Council of Constantinople (879–880)

With about 383 bishops and papal legates, it recognized Photius (restored after Ignatius' death in 877) as legitimate patriarch and annulled the council of 869–870. It reaffirmed the Niceno-Constantinopolitan Creed and forbade adding to or subtracting from it, which Orthodox tradition reads as an implicit rejection of the Filioque.

Convoked by

Emperor Basil I, with legates of Pope John VIII

Some Orthodox theologians and documents regard it as the eighth ecumenical council; the Orthodox Church has not formally defined it as such. The Catholic Church does not count it as ecumenical.