Summary Council of Nicaea

The veneration of icons had been banned by Emperor Leo III because he suspected Christians as executing Idolatry among religious matters but he died in AD 741 but the iconoclasm hasn’t been stopped there because it was continued by his successors especially his son Constantine V, In 754 Constantine summoned the Council of Hieria in which some 330 to 340 bishops participated and which was the first church council to concern itself primarily with religious imagery. Constantine seems to have been closely involved with the council and it endorsed an iconoclast position. The council of Hieria treat itself as the 7th ecumenical council. But 33 years later the Second Council of Nicaea called by Empress Irene that is supported by Pope Adrian I overturned the council of Hieria. The Second Council of Nicaea II met in AD 787 in Nicaea to restore the veneration of religious icons.
In AD 786, the council met first time in the Church of the Holy Apostles in Constantinople. However, soldiers in collusion with the opposition entered the church, and broke up the assembly. As a result, the council stop their session.
The council was again summoned to meet, this time in Nicaea, since Constantinople was still distrusted. The council assembled on September 24, 787 at the church of Hagia Sophia. It numbered about 350 members; 308 bishops or their representatives signed. Tarasius presided and seven sessions were held in Nicaea.
Proceedings of the Council
First Session (September 24, 787) — Three bishops, Basilius of Ancyra, Theodore of Myra, and Theodosius of Amorium begged for pardon for the heresy of iconoclasm.
Second Session (September 26, 787) — Papal legates read the letters of Pope Hadrian I asking for agreement with veneration of images, to which question the bishops of the council answered: "We follow, we receive, we admit".
Third Session (September 28, 787) — Other bishops having made their abjuration, were received into the council.
Fourth Session (October 1, 787) — Proof of