Byzantine Iconoclasm

For much of the eighth and ninth centuries, emperors and church councils in the Byzantine Empire opposed the veneration of religious images, or icons, of Christ, the Virgin and the saints. The controversy came in two waves, roughly 726 to 787 and 814 to 843, and ended with the restoration of icons. It shaped Orthodox worship for good and widened the rift between Constantinople and the papacy.

By the sixth century Christians commonly asked saints to intercede for them, and they valued relics and holy images as points of contact with the divine. Icons multiplied after the reign of Justinian I, and some were credited with miraculous powers, including images said to have been made "not by human hands". This growing devotion also drew critics, who pointed to the biblical ban on graven images. Older explanations linked the movement to the influence of Islam's rejection of images or to divisions between eastern and western provinces, but both ideas are now disputed.

A great volcanic eruption between Thera and Therasia in 726 was read by many, probably including Emperor Leo III, as a sign of divine anger. Later accounts say Leo had an image of Christ over the Chalke Gate of the imperial palace replaced with a cross, and that he banned the veneration of images in 730. Patriarch Germanos either resigned or was removed. Modern historians are cautious, however: the main sources were written long afterwards by fierce opponents of iconoclasm, and Germanos's own letters suggest the dispute first arose among provincial bishops. In Rome, Pope Gregory III condemned Leo's measures, and Leo responded by transferring papal estates in Calabria and Sicily, together with church authority over Illyricum, to the patriarch of Constantinople.

Leo's son Constantine V, who reigned from 741 to 775, was a committed opponent of images. In 754 he convened the Council of Hieria, where 338 bishops condemned religious painting and claimed the status of an ecumenical council, though no patriarchs or papal envoys attended. Hostile sources accuse Constantine of attacking monasteries and monks, and the monk Stephen the Younger, killed in 765, was later honoured as a martyr. Outside the empire, the Syrian monk John of Damascus wrote influential defences of icons.

After the brief reign of Leo IV, his widow Irene ruled for their young son Constantine VI and called a new council. Disrupted by iconoclast soldiers in Constantinople in 786, it reassembled at Nicaea in 787. On 13 October that year the Second Council of Nicaea decreed that images should be honoured, while making clear that true worship belonged to God alone. Unlike Hieria, it included papal legates, and the Orthodox Church counts it as the seventh and last genuine ecumenical council.

Heavy defeats by the Bulgarian ruler Krum, in which Emperor Nikephoros I was killed, revived the old idea that icons had angered God. Leo V reinstated iconoclasm in 815 through a synod held in Hagia Sophia, and his successors Michael II and Theophilos maintained it. When Theophilos died, his widow Theodora, regent for the child Michael III, restored the icons at a council in Constantinople in 843, on condition that her late husband was not condemned. The Orthodox Church still marks the first Sunday of Lent as the Triumph of Orthodoxy.

The papacy backed images throughout, and the quarrel deepened the divergence between the Byzantine and Carolingian worlds within a still-united church, a drift that eventually ended in the East–West Schism. It also helped loosen Byzantine control over parts of Italy. Some historians see the controversy as an influence on the Protestant Reformation.

Our 700 map shows the empire shortly before the controversy began, and our 800 map shows it in the iconoclast era, alongside the rising Carolingian Empire in the west.