Disturbed not only by the extension of the German influence in the Balkans and by the use of the Filioque, in 867 Photius took action. He wrote an Encyclical Letter to the other Patriarchs of the east, denouncing the Filioque at length and charging those who used it with heresy. Photius has often been blamed for writing this letter. The great Catholic historian Francis Dvornik who is in general highly sympathetic to Photius, calls his action on this occasion a futile attack, and says the lapse was inconsiderate, hasty, and big with fatal consequences’. But if Photius really considered the Filioque heretical, what else could he do except speak his mind? It must also be remembered that it was not Photius who first made the Filioque a matter of controversy, but Charlemagne and his scholars 70 years before.

Photius followed up his letter by summoning a council to Constantinople, which excommunicated Pope Nicolas, terming him a heretic who ravages the vineyard of the Lord.

At this critical point in the dispute, the whole situation suddenly changed. In this same year (867) Photius was deposed by the Emperor. Ignatius became Patriarch once more and communion with Rome was restored. In 869-70 another council was held at Constantinople, known as the Anti-Photian Council, which condemned and anathematized Photius, reversing the decisions of 867. This council, later reckoned in the west as the eighth Ecumenical Council, opened with the unimpressive total of 12 bishops, although numbers at subsequent sessions rose to 103.

Further changes, however, were to come. The 869-70 council requested the Emperor to resolve the status of the Bulgarian Church and not surprisingly he decided that it should be assigned to the Patriarchate of Constantinople. Realizing that Rome would allow him less independence than Byzantium, Boris accepted this decision. From 870, then, the German missionaries were expelled and the Filioque was heard no more in the confines of Bulgaria. Nor was this all. At Constantinople, Ignatius and Photius were reconciled to one another and, when Ignatius died in 877, Photius once more succeeded him as Patriarch. In 879 yet another council was held attended by 383 bishops – a notable contrast with the   meager total at the anti-Photian council. The council of 869 was anathematized and all condemnations of Photius were withdrawn and these decisions were  accepted without protest at Rome.