Byzantine Empire

In 330, the Roman emperor Constantine I moved his seat east to Byzantium, renaming it Kōnstantinoupolis, "Constantine's city". In 395, Theodosius I officially divided the empire into two between his sons: the Western Roman Empire based in Rome and the Eastern Roman Empire with its seat in Constantinople.

At its time, the Byzantine Empire was known as the East Roman Empire or Romania, a name surviving in today's Romania, and the inhabitants never saw themselves anything other than Romans proper — the term "Byzantine" (derived from Byzantium, the oldest name of Constantinople/Istanbul) was coined after the fall of the empire, in 1557, by German scholar Hieronymus Wolf to distinguish the mainly urban, Greek-speaking, and Eastern Orthodox empire from its less urban, Latin-speaking, and Roman Catholic counterpart in the west.

The Byzantine Empire is one of few political entities in Europe to have survived for more than a thousand years, throughout the period known as the European Middle Ages, and its legacy is still visible in today's Balkans, Greece and Turkey. Prejudices about the Byzantine Empire (cf. the adjective "byzantine" negatively describing a bureaucracy, or the "Byzantine generals problems" in information science, alluding to the frequent treason in the armed forces) would have one believe that it was a hopelessly corrupt, terminally declining polity, but the fact that it held on to as much territory as it did for a millennium, adeptly navigating a world of numerous would-be destroyers of the empire, without the possibility of relying on overwhelmingly crushing military supremacy as the old Western Roman Empire could, shows a fascinatingly advanced and complex society.

Being the foremost Christian empire of its day, religion played a large part in Byzantine history; often domestic conflicts were clad in different interpretations of Christianity, and to this day some schisms dating to Byzantine era conflicts remain. Later on, the Byzantine Empire would see itself as the "last bastion" of Christendom against the Islamic expansion in the east, but adept Byzantine diplomacy made alliances with Christian, Muslim and even pagan rulers, for example Vladimir, ruler of Kievan Rus — the earliest iteration of the Russian Empire — who converted to Christianity, married Anna Porphyrogenita, sister of emperor Basil II Bulgaroktonos (the Bulgar-Slayer), came back to his capital and officially baptized his subjects in the Orthodox Christian faith by the Dnieper River in 988. After the end of the empire, prince Ivan III "the Great" of the Rurikid dynasty and princess Sophia Palaiologina of the last Byzantine dynasty were married on 12 November 1472. Their grandson Ivan IV "the Terrible" was the first prince of Muscovy to style himself "Tsar", aka "Caesar", and would lay Moscow's claim of "the third Rome that shall not fall".

The Eastern Empire conquered large parts of the former West - most prominently the Exarchates of Ravenna and Africa - under Emperor Justinian with his able general Belisarius. However, his dynasty was the last whose primary language was Latin; Maurice, Phocas, the Heracliads and all subsequent dynasties were Greek speakers, calling themselves not "Augustus" but Βασιλεύς "Basileus" — following the establishment of the rival Holy Roman Empire in Western Europe in 800, the use of the title Αὐτοκράτωρ "Autokrator" became prevalent. The Pope justified his crowning of Charlemagne as "emperor" (of which there was supposed to be only one) by the fact that at the time the Eastern Roman Empire was governed by a woman and according to the sexist mores of the time, a woman could not possibly be emperor (the official biography of Charlemagne, written by his courtier Einhard claims that the crowning came as a surprise to Charlemagne and he did not want it, but had to accept it). At this time, the empire was already engaged in a long struggle against the expansion of Islam and sometimes even against other Europeans, particularly the Roman Catholics, as the Byzantine Empire became Eastern Orthodox following the schism between the East and West in 1054.

From the conclusion of the reign of Justinian in the 6th century until the beginning of the 13th century, the empire went through alternating periods of military or economic success and decline, varying from dynasty to dynasty. Following the August 636 Battle of Yarmouk, a decisive Muslim victory that ended Byzantine rule in the Levant, it spent the next few hundred years holding onto its possessions in present-day Greece and Asia Minor until the 1071 Battle of Manzikert, which opened Asia Minor to Turkish invasion and a new Crusader influence from the West, and furthered the decline in the empire's sphere of influence.

The biggest calamity to befall the empire before its ultimate fall was not at the hand of any "heathen", but the Christian crusaders of the 1204 Fourth Crusade, led by the greedy Venetian merchants who owned the boats. As a result, the Byzantine Empire temporarily lost control of Constantinople to the Latin Empire, a puppet of Venice (Doge Enrico Dandolo was buried inside Hagia Sophia; his tombstone can still be seen), which would've spelled the end of any lesser polity. However, the empire recovered and reconquered its capital in 1261. It soldiered on and called itself "Roman" until 29 May 1453, when Constantinople fell to the Ottoman Turks after a 53-day siege and the last emperor was killed in action, last seen fighting the attackers after he had removed all rank insignia to die as a Roman.

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