Megara also colonizes northward and eastward on the Bosporus River and Sea of Marmara at Chalcedon (676) on a site so obviously inferior to that of Byzantium (on the opposite shore) that it is soon accorded the name of the “city of the blind.”

…Chalcedon on the Bosporus.

Probably no other event in late Achaemenid history reveals more clearly to the Greeks the essential internal weakness of the Achaemenid Empire than the escape of so large a body of men from the very heart of the Great King's domain.

Mithridates, launching an attack at the same time as the revolt by Sertorius is sweeping through the Spanish provinces, is initially virtually unopposed.

The Senate responds by sending the consul Lucius Licinius Lucullus to Cilicia to deal with the Pontic threat.

The only other possible general for such an important command, Pompey, is in Gaul, marching to Hispania to help crush the revolt led by Sertorius.

Marcus Aurelius Cotta, having received Bithynia and Pontus as his proconsular command, had taken charge of a fleet to protect his province, having been dispatched to the east towards the end of his period as consul.

Lucullus, upon arrival in Cilicia and immediately sets forth to confront the Pontic army in Bithynia.

The original plan was that Cotta should tie down Mithridates' fleet, while Lucullus attacked by land.

Cotta had therefore been ordered to station his fleet at Chalcedon, while Lucullus marches through Phrygia with the intention of invading Pontus.

Lucullus has not advanced far when news comes through that Mithridates has made a rapid march westward, attacked Cotta, and forced him to flee behind the walls of Chalcedon.

Sixty-four Roman ships have been captured or burnt, and Cotta has lost three thousand men.

Here Cotta is forced to remain until Lucullus can to come to his rescue.

...Chalcedon.

The invasion results in success, marking the greatest extent of Palmyrene dominance over the east once they reach Ancyra.

The invasion paves the road for Zenobia's imperial claims and her subsequent breakaway and the independence of the short-lived Palmyrene Empire.

Julian holds a tribunal at the city of Chalcedon, which is at this time a suburb of Constantinople, shortly after the death of Constantius.

Saturninius Secundus Salutius, who is raised to the rank of Praetorian Prefect, is given the chief oversight and with him are associated Claudius Mamertinus (another civilian), and four military commanders, Arbitio, Agilo, Nevitta and Jovinus.

The first two are ex-officers of Constantius, while the other two had served with Julian.

At this tribunal a large part of Constantius's ministers are brought to trial.

In charge of the daily inquisitions is Arbitio, "while the others were present merely for show" according to historian Ammianus Marcellinus.

Palladius, Taurus, Euagrius, Saturninus and Cyrinus are known to have been exiled.

Florentius, Ursulus and Eusebius are condemned to death.

Apodemius and Paulus Catena are even burned alive.

Another Florentius is imprisoned on a Dalmatian island.

As Constantius II died on October 5, 361, all this must have happened in late 361 and early 362.

Valens, left with the task of dealing with Procopius, considers abdication and perhaps even suicide, but soon steadies his resolve to fight.

His efforts to forestall the usurper are hampered by the fact that most of his troops had already crossed the Cilician gates into Syria when he learned of the revolt.

Even so, Valens sends two legions to march on Procopius, who easily persuades them to desert to him.

Valens himself is nearly captured in a scramble near Chalcedon.

Troubles are exacerbated by the refusal of Valentinian to do any more than protect his own territory from encroachment.

The failure of imperial resistance in 365 allows Procopius to gain control of the dioceses of Thrace and Asiana by year's end.

Eunomius of Cyzicus, deposed from his bishopric by Constantius for his extreme Arianist views, had resided in Constantinople during the reigns of Julian and Jovian, in close intercourse with his mentor Aëtius, consolidating an heretical party and consecrating schismatical bishops.

He had then gone to live at Chalcedon, whence in 367 he is banished to Mauretania for harboring the rebel Procopius.

He is recalled, however, before he reaches his destination.

Marcian, at the urging of Pope Leo, convokes the Christian church’s fourth ecumenical council, the Council of Chalcedon, in 451, primarily to resolve theological disputes about the person of Jesus Christ.

The council formally condemns the so-called Robber Synod and, once again, reaffirms the Nicene Creed.

Repudiating the Monophysite emphasis on the divinity of Christ over his humanity, the council promulgates a dogmatic statement called the "Faith of Chalcedon," which describes Christ as possessing two natures, divine and human, "without confusion, without change, without division," perfectly united in a single person.

The council, like its predecessor at Ephesus, upholds the title “theotokos” as descriptive of Mary.

The council also condemns the practice known as simony (after Simon Magus, who, according to “Acts of the Apostles,” attempted to buy the gifts of the Holy Spirit for Peter), in its most common form of buying church offices.

Leo steadfastly rejects the council’s bid to raise the status of the patriarch of Constantinople and make his see second only to Rome.

Theodoret, although identified with the Nestorian opposition, is persuaded to renounce Nestorius and is recognized as orthodox.

Eutyches is condemned, deposed, and exiled.

The council’s condemnation of Eutyches’ doctrine of Monophysitism alienates the churches of Egypt, Ethiopia, Syria, Mesopotamia, and Armenia, creating dissension in the Eastern Roman Empire.

Ecclesiastical conflict meanwhile continues.

The Council of Chalcedon, convened in 451 by Pope Leo and the Eastern emperor, is the most notable event of Marcian's reign.

This fourth ecumenical council issues twenty-seven canons governing the Church; it upholds the orthodox Christian doctrine that Christ had two natures, divine and human, and rejects Monophysitism, which maintains that Christ had one divine nature.

As a result of this council, the Oriental Orthodox churches eventually become a separate communion.

More immediately, Jerusalem becomes a Patriarchate and Dioscorus of Alexandria is deposed as patriarch of Antioch.

The Persians reach the Bosporus by 608, laying siege to Chalcedon.