Constantinople
Constantinople (; ) was the capital city of the Roman/Byzantine Empire (330–1204 and 1261–1453), and also of the brief Crusader state known as the Latin Empire (1204–1261), until finally falling to the Ottoman Empire (1453–1923). It was reinaugurated in 324 from ancient Byzantium as the new capital of the Roman Empire by Emperor Constantine the Great, after whom it was named, and dedicated on 11 May 330. The city was located in what is now the European side and the core of modern Istanbul.
History of the East–West Schism
After the sole emperor of all the Roman Empire Constantine built the new imperial capital at Byzantium, a strategically placed city on the Bosporus. He renamed his new capital "Nova Roma" ("New Rome"), but the city would become known as Constantinople. The centre of gravity in the empire was fully recognised to have completely shifted to the eastern Mediterranean. Rome lost the Senate to Constantinople and lost its status and gravitas as imperial capital, see also Fall of Rome.
Soon the local bishop was elevated to Patriarch under Constantine, as Metrophanes of Byzantium
The patriarchs of Constantinople often tried to adopt an imperious position over the other patriarchs. In the case of Nestorius, whose actual teaching is now recognised to be not overtly heretical, although it is clearly deficient, (Saint Cyril called it 'slippery'), other patriarchs were able to make the charge of heresy stick and successfully had him deposed. This was probably more because his Christology was delivered with a heavy sarcastic arrogance which matched his high-handed personality.
In the fourth century, when the Roman emperors (reigning in Constantinople) were trying to control the Church, theological questions ran rampant throughout the Roman Empire. The influence of Greek speculative thought on Christian thinking led to all sorts of divergent and conflicting opinions. Theology was also used as a weapon against opponent bishops, because being branded a heretic was the only sure way for a bishop to be removed by other bishops—incompetence was not sufficient grounds for removal.