Chalcedon
The site of Chalcedon is located on a small peninsula on the north coast of the Sea of Marmara, near the mouth of the Bosphorus. A stream, called the Chalcis or Chalcedon in antiquity and now known as the Kurbağalıdere (Turkish: "stream with frogs"), flows into Fenerbahçe bay. There Greek colonists from Megara in Attica founded the settlement of Chalcedon in 685 BC, some seventeen years before Byzantium.
Acacius of Constantinople
Acacius advised the Byzantine emperor Zeno to issue the Henotikon edict in 482, in which Nestorius and Eutyches were condemned, the twelve chapters of Cyril of Alexandria accepted, and the Chalcedon Definition ignored. This effort to shelve the dispute over the Orthodoxy of the Council of Chalcedon was quite in vain. Pope Felix III saw the prestige of his see involved in this slighting of Chalcedon and his predecessor Leo's epistle. He condemned and deposed Acacius, a proceeding which the latter regarded with contempt, but which involved a schism between the two sees that lasted after Acacius's death. The Acacian schism lasted through the long and troubled reign of the Byzantine emperor Anastasius I, and was only healed by Justin I under Pope Hormisdas in 519.