The first phase of the Iconoclasm started between 726 and 730, when Leo III the Isaurian prohibited prostration before icons by means of decrees. As a result, the majority
of the Byzantine clergy and people reacted against this, while declaring its opposition to the Church of Rome. The Pope tried to take advantage of the occasion in order to be released from tax obligations liable to the eastern state. Leo punished him depriving from his jurisdiction the Church of Illyrian (Southern Italy - Sicily and Greece) and subsuming it under the jurisdiction of the Patriarchate of Constantinople.
Fanaticism and animosities were dominant in this phase of Iconoclasm. Leo´s successor, Constantine V launched persecutions against the monks. Furthermore, by means of a council that took place in the palace of Hiereia in 754, he condemned icons as well as their worship. In his days
the discussions regarding icons assumed christological content, since the depiction of Christ was related to the dogma of the Holy Incarnation. In these theological discussions the emperor himself frequently intervened. His iconoclast beliefs were shared also by his son and successor, Leo IV. His early death, however, did not allow him to express his iconoclast inclinations. His wife Irene assumed power in 780 as guardian of her son Constantine VI tuned in favour towards the iconolaters and with the Seventh Ecumenical Council she convened in Nicaea, in 787, she restored icons putting an end to the first phase of the Iconoclasm.