St.Photios was the Patriarch of Constantinople when a temporary schism erupted between Rome and the Ecumenical Patriarchate, in part due to ecclessiastical politics in Constantinople which Rome decided to involve itself in, in part because it came to the attention of St.Photios that the use of an altered version of the Creed was quite common in the west.
The issue was resolved in a highly interesting manner. Up until the early part of the 20th century, it was quite common for Roman Catholics to lay a great deal of blame on this temporary schism upon St.Photios. However, this is curious since this schism was resolved with St.Photios being vindicated both as an individual and his doctrinal stand (against the filioque interpolation into the Nicene-Constantinoplean Creed).
In 879/880 A.D. a Council was convened in Constantinople, which in all of it’s trappings was no different than the previous Ecumenical Councils. In fact, while you’ll hear Orthodox speak of the big “Seven Councils”, in reality the entirity of this council is accepted with the same authority, and has even been explicitly spoken of now and in the past as the “eighth council” – in the epistle of the Eastern Patriarchs of 1848 to the Pope of Rome, they make mention of this.
What is most significant though, at least for western Christians, is that Pope John VIII [b:11l3b6u8]signed the acts of this council[/b:11l3b6u8]. Of course, this council was soon “dropped from the ‘list'” by the Popes after 1054 A.D., and instead replaced with the pseudo-synod (that condemned St.Photios unjustly) which the actual “eighth council” had sought to undo!