CHALCE'DON, a city of ancient Bithynia, at the entrance of the Euxine, opposite to Byzantium. It was founded 684 n.c. by a colony from Megara, and soon became a place of considerable trade and importance. It contained several temples, one-of which, ded icated to Apollo, had an oracle. C. was taken Persians, suffered the vicissitudes of war during the strife for Grecian supremacy between the Athenians and Lacedemo nians, and finally merged into the Roman empire. During the Mithridatic war, it was the scene of a bold exploit of the Pontic sovereign. Having invaded Bithynia, all the wealthy Romans in the district fled for refuge to whereupon he broke the chains that protected the port, burned four ships, and towed away the remaining sixty. Under the empire it was made a free city, and was the scene of a general council, held 451 A.D. Chosroes the Persian captured it 616 A.D., after which it declined, until it was finally demolished by the Turks, who used its ruins to build mosques and other edifices at Con stantinople. C. was the birthplace of the philosopher Xenocrates.
The council of C., to which allusion has been made, was the fourth universal council, and was assembled by the emperor Marcian for the purpose of up a form of doctrine in regard to the nature of Christ, which should equally avoid the errors of the Nestorians (q.v.) and Monophysites (q.v.). Six hundred bishops, almost all of the east ern or Greek church, were present. The doctrine declared to be orthodox was, that in Christ• there were two natures, which could not be intermixed (this clause was directed against the Monophysites), and which also were not in entire separation (this was directed against the Nestorians), but which were so conjoined, that their union destroyed neither the peculiarity of each nature, nor the oneness of Christ's person.