History of the Byzantine Empire

The Byzantine Empire was one of the longest-lasting civilizations in human history, surviving for over a thousand years in a region that today forms the heart of modern Turkey, Greece, and the Balkans. At its peak, it was the most powerful economic, cultural, and military force in Europe, preserving the legal, intellectual, and artistic heritage of the Roman world while developing its own distinct identity rooted in Orthodox Christianity, Greek language, and Roman political tradition.

This overview traces the full arc of Byzantine history, from the moment Emperor Constantine the Great refounded Byzantium as Constantinople in 330 AD, through the great dynasty of Justinian, the trauma of Iconoclasm, the brilliant revival of the Macedonian Dynasty, the catastrophic Fourth Crusade, and the slow decline that ended when Ottoman cannons breached the walls of Constantinople on 29 May 1453.

The Origins: From Rome to the New Rome

Constantine and the Foundation of Constantinople (306–337 AD)

The story of Byzantium begins with a Roman emperor. Constantine I, known as Constantine the Great, ruled the Roman Empire at a moment of profound crisis. After years of civil war and persecution of Christians, he sought a new capital that would anchor the eastern half of the empire. In 330 AD, he dedicated the city of Constantinople on the site of the ancient Greek colony of Byzantion.

The choice was strategic. Constantinople sat at the crossroads of Europe and Asia, controlling the Bosphorus straits that link the Black Sea to the Mediterranean. It could be supplied by sea and protected by formidable land walls. Constantine populated his new capital with citizens drawn from across the empire, endowed it with the great church of Hagia Eirene, and granted it the title “New Rome.” Within decades, the city would also become the seat of Christian imperial authority, especially after the dedication of the original Hagia Sophia by his son Constantius II.

Constantine’s conversion to Christianity, proclaimed by the later tradition in his vision at the Milvian Bridge in 312, transformed not only the empire but the course of Western civilization. From this point forward, church and state would be intertwined in Byzantine political thought in a way that had no parallel in the Latin West.

The scale of what Constantine set in motion is hard to overstate. Writing a generation later, Eusebius of Caesarea described the emperor as God’s earthly vice-regent, “a copy of the heavenly kingdom” on earth — a formulation that would shape Byzantine political theology for the next millennium.

The Late Roman Empire (337–518 AD)

For nearly two centuries after Constantine, the Roman Empire continued to function as a single, if increasingly divided, state. Emperors like Theodosius I, who in 380 AD made Nicene Christianity the official religion of the empire, ruled from Constantinople or Milan. The administrative division between Eastern and Western halves became formal in 395 AD, when Theodosius bequeathed the empire to his two sons.

The fifth century was catastrophic for the Western Roman Empire. Germanic tribes, the Huns, and internal decay brought the western line of emperors to an end in 476 AD. The Eastern Empire, meanwhile, survived. Defended by the formidable walls of Constantinople, by Greek fire, and by a sophisticated diplomacy that played rivals against each other, the eastern state endured. Justinian would later boast that the empire knew no boundaries, but in practice, the Eastern Empire was becoming a Greek-speaking, Orthodox Christian civilization increasingly distinct from the Latin West.

The Age of Justinian (518–602 AD)

Justinian I and the Restoration of Roman Power

The single most important reign in Byzantine history began in 527 AD, when Justinian I ascended the throne. Justinian was a Latin-speaking peasant from Illyricum who had been adopted by his uncle, the emperor Justin I. He was also one of the most ambitious rulers in world history. His goal was nothing less than the restoration of the entire Roman Empire, and he came closer to achieving it than any ruler after Theodosius.

Justinian’s military generals, including the brilliant Belisarius and the eunuch Narses, reconquered North Africa from the Vandals, Italy from the Ostrogoths, and parts of southern Spain from the Visigoths. The Vandalic War (533–534) and the Gothic War (535–554) doubled the size of the empire and restored Mediterranean unity. These campaigns also produced the legend of Empress Theodora, Justinian’s wife, who reportedly saved his throne during the Nika Riots of 532 by refusing to flee and exhorting him to act with resolve.

Law, Architecture, and Faith

Beyond the battlefield, Justinian’s legacy is most clearly visible in three areas. First, the Justinian Code, compiled under the direction of the jurist Tribonian, became the foundation of civil law across Europe and remains influential today. Second, the rebuilding of the Hagia Sophia after the Nika Revolt produced what was, for a thousand years, the largest cathedral in the world. Third, the doctrinal work of the Fifth and Sixth Ecumenical Councils, held in Constantinople, defined orthodox Christianity against Monophysite and Monothelite heresies.

Yet the cost of this greatness was severe. The wars of reconquest exhausted the treasury, the population, and the army. By the time of Justinian’s death in 565, the empire was overextended, and within a generation much of Italy had been lost to the Lombards.

Crisis and Transformation (602–717 AD)

The Sassanid Threat and the Loss of the East

The seventh century was, in many ways, the nadir of Byzantine history. The Sassanid Persians under Khosrow II invaded the empire, capturing Jerusalem in 614 and sacking it, and even briefly threatening Constantinople itself. The emperor Heraclius, who came to power in 610, mounted one of the most remarkable military campaigns in history, marching his army deep into Persian territory and ultimately forcing a peace that returned the True Cross to Jerusalem in 628.

Heraclius had little time to celebrate. Within just a few years, a new and even more dangerous enemy appeared on the southern frontier: the armies of Islam. At the Battle of Yarmouk in 636, the Byzantines suffered a catastrophic defeat that lost them Syria, Palestine, and Egypt, the empire’s richest grain-producing provinces. Within a century, the Byzantines would also lose North Africa to the Arabs.

The Defensive Triumph of the Isaurian Dynasty

The Isaurian dynasty, founded by Leo III in 717, transformed the empire from a Mediterranean power into a defensive Greek-speaking state. The new strategic innovation was the theme system, a militarized administrative structure that bound soldier-farmers to specific provinces in exchange for land grants. This system produced a formidable defensive army and helped Byzantium survive the second great Arab siege of Constantinople in 717–718, which proved to be the high-water mark of the Umayyad Caliphate.

The Isaurians also initiated the great religious controversy of Byzantine Iconoclasm, a debate over the veneration of religious images that divided the empire for more than a century. Beginning in 726 and lasting in two phases until 843, Iconoclasm was at once a theological dispute, a political assertion of imperial authority over the church, and, some historians argue, an attempt to align Byzantine practice with the iconoclastic sensibilities of Islam and Judaism.

The Macedonian Renaissance (867–1056)

The Rise of the Macedonian Dynasty

The accession of Basil I, a peasant from Macedonia who murdered his way to the throne, inaugurated the most brilliant and stable period in Byzantine history. The Macedonian Dynasty, which ruled from 867 to 1056, presided over a true renaissance in art, literature, law, and military power.

Under rulers like Leo VI the Wise, Constantine VII Porphyrogennetos, and Basil II the Bulgar-Slayer, the empire reached a level of cultural achievement comparable to the Italian Renaissance seven centuries later. Constantine VII’s works on imperial ceremony, military tactics, and diplomacy were read and copied for centuries. The Macedonian era also saw the conversion of the Slavs, the Bulgarians, and the Serbs to Orthodox Christianity, extending Byzantine cultural influence deep into Eastern Europe.

Basil II, who reigned from 976 to 1025, was the greatest military emperor since Justinian. He smashed the Bulgarian Empire at the Battle of Kleidion in 1014, allegedly blinding 15,000 prisoners and leaving one in every hundred with one eye to lead the rest home. He annexed Bulgaria, expanded into Armenia and Georgia, and at his death ruled an empire that stretched from southern Italy to the Caucasus and from the Danube to Syria.

The Crisis of the Eleventh Century (1025–1081)

The Macedonian achievement was squandered within a generation. Basil II left no capable heir, and the dynasty collapsed into a series of weak, often short-lived rulers dominated by court eunuchs and aristocratic families. The great military families of Anatolia, neglected by the central government, began to build up private power bases that would eventually evolve into Turkish beyliks.

The catastrophe came in 1071, when the Seljuk Turkish sultan Alp Arslan crushed the Byzantine army at the Battle of Manzikert in eastern Anatolia. Within a decade, most of Anatolia, the empire’s recruiting ground and economic heartland, was lost to Turkish control. Although the Byzantines would hold cities and coastal regions in Anatolia for centuries, they would never again control the interior plateau.

The disaster of Manzikert coincided with, and in part caused, the religious schism with the Latin West known as the Great Schism of 1054, which divided Christianity into its Orthodox and Catholic branches. The two events were not unrelated: the emperor’s request for military aid from the Pope in exchange for reuniting the churches set the stage for the Crusades.

The Comnenian Restoration and the Crusades (1081–1204)

The Comnenian dynasty, beginning with Alexios I in 1081, partially restored Byzantine fortunes. Alexios was a brilliant diplomat and general who used Western Crusader armies, originally summoned to help against the Seljuks, as mercenaries in his campaigns against the Seljuk and Pecheneg enemies in Asia Minor and the Balkans. The relationship with the Crusaders was, however, always tense. Western and Greek Christians had grown apart in language, ritual, and political culture, and the Comneni struggled to control the unruly Crusader armies passing through their territory.

The Comnenian court produced the most famous woman historian of the medieval world, Anna Komnene, who set out in the Alexiad to defend her father’s reputation against the accusations of the Western chroniclers. Of the Crusaders’ passage through Byzantine territory, she writes with biting irony: “Whenever they passed a city or a fortified place, the inhabitants fled in all directions, just as sheep scatter when the wolf appears. The barbarians would have done nothing dreadful if they had only been content to seize the property of the inhabitants; but, as it was, they would not spare even the holy and venerable monasteries.”

The Crusades, intended to help Byzantium, ultimately destroyed it. The Fourth Crusade, diverted from its original objective of attacking Egypt, was instead directed at Constantinople itself by the scheming prince Alexios IV Angelos and the doge of Venice, Enrico Dandolo. In 1204, the Crusaders sacked Constantinople, an event of such trauma that modern Greeks still refer to it simply as “the Catastrophe.” The city was subjected to three days of pillage, its libraries burned, its churches desecrated, and its population reduced from perhaps half a million to fifty thousand.

The Empire in Exile and the Palaiologan Twilight (1204–1453)

The States of the Dispersion

After 1204, Byzantine power survived in three successor states: the Empire of Nicaea in western Asia Minor, the Despotate of Epirus in northwestern Greece, and a small Latin Empire in Constantinople itself. The ruler most responsible for the restoration was Michael VIII Palaiologos, who in 1261 recaptured Constantinople in a daring nighttime assault.

The restored Palaiologan empire was, however, a shadow of its former self. It controlled little more than Constantinople, parts of Thrace and Macedonia, and a few Aegean islands. Surrounded by the restored Bulgarian Empire, the Serbian Empire of Stefan Dušan, and the rising Ottoman Turkish state in Anatolia, the Byzantines played a desperate game of diplomatic and military survival.

The Final Century

The last Byzantine emperor, Constantine XI Palaiologos Dragases, came to the throne in 1449, ruling a state that consisted essentially of the city of Constantinople and a thin strip of land around it. On 6 April 1453, the Ottoman sultan Mehmed II laid siege to the city with an army estimated at 80,000 men and a fleet of over 100 ships. The siege lasted 53 days. On 29 May 1453, after the famous giant cannon built by the engineer Orban had finally breached the Theodosian walls, Ottoman troops poured into the city. Constantine XI, according to tradition, charged into the breach and died fighting. The last Roman emperor fell, and with him, the empire he represented.

The eyewitness account of the soldier-scholar Doukas, who survived the final assault, captures the moment: “The desecrated churches, the devastated houses, the palaces overturned from their foundations, the sacred vessels of the Holy Church lying in the mire of the streets, the holy icons stripped of their ornamentation… the city, the common nurse of all the Christians, emptied of all her adornments, and given over to the barbarians, became a habitation of wild beasts.” His Decline and Fall of Byzantium — written in the rough, angry Greek of a survivor rather than the literary Attic of the elite — is the single most moving of the contemporary sources.

The fall of Constantinople sent shockwaves across the Christian world. In Rome, bells tolled. In Russia, the Grand Duke of Moscow began to claim the mantle of the third Rome, the inheritor of Byzantine imperial and religious tradition. Greek scholars fleeing west would help spark the Italian Renaissance. The Ottoman Empire, now anchored in Europe, would dominate the eastern Mediterranean for the next four centuries.

Themes and Patterns in Byzantine History

Several patterns emerge from this thousand-year survey. First, the Byzantine state was remarkably resilient, capable of recovering from disasters that would have destroyed lesser polities. Manzikert, the loss of Anatolia, the Fourth Crusade, the Black Death, and the final Ottoman onslaught all seemed fatal, yet the empire persisted.

Second, the relationship between church and state was central. Unlike the Latin West, where popes and emperors contested power, in Byzantium the emperor claimed authority over the church, which both unified the state and created repeated conflicts with those who resisted imperial interference in doctrine, especially during Iconoclasm and the monastic hesychast controversy.

Third, Byzantine diplomacy was as important as Byzantine arms. Emperors skillfully played nomadic steppe peoples, Western powers, and Islamic caliphates against one another, preserving Byzantine independence long after the empire’s military strength had declined.

Fourth, Byzantine art, architecture, and religion preserved and transmitted classical learning, Christian theology, and Hellenistic aesthetic principles across centuries, directly shaping the Byzantine legacy in modern Greece, Russia and Eastern Europe, and the Italian Renaissance.

Notable Byzantine Emperors

A complete study of Byzantine emperors reveals a remarkable range of personalities, from the saintly and devout to the monstrous and cruel. The list includes some of the most consequential rulers in world history:

• Constantine I (306–337): Founder of Constantinople and champion of Christianity.
• Justinian I (527–565): Restorer of Roman imperial power and codifier of Roman law.
• Heraclius (610–641): Defender of the empire against the Persians and innovator of Greek as the language of state.
• Leo III (717–741): Founder of the Isaurian dynasty and originator of Iconoclasm.
• Basil II (976–1025): The Bulgar-Slayer, the last great conquering Byzantine emperor.
• Alexios I Komnenos (1081–1118): Diplomat who summoned the First Crusade.
• Michael VIII Palaiologos (1259–1282): Recaptured Constantinople in 1261.
• Constantine XI Palaiologos (1449–1453): The last Byzantine emperor, who died defending his city.

Sources & Further Reading

A single-volume overview in English is still John Julius Norwich, A Short History of Byzantium (Knopf, 1997). For something more recent, Michael Angold, Byzantine Political History (Routledge, 2019) is reliable and opinionated. The standard scholarly treatment, with full apparatus, is Cyril Mango (ed.), The Oxford History of Byzantium (Oxford UP, 2002); the chapters by Anthony Kaldellis, Mark Whittow, and John Haldon are particularly good. On the early period, Peter Heather and John Matthews offer different angles — Heather, The Fall of the Roman Empire (2005), reads the end of the West as a non-Byzantine failure, while Averil Cameron, The Byzantines (Blackwell, 2009), is the best short introduction to the eastern half.

For deeper reading, the older narrative histories remain useful: George Ostrogorsky, History of the Byzantine State (Rutgers, 1969) is the classic German-tradition survey, and Steven Runciman’s three volumes on the Crusades (A History of the Crusades, 1951–54) and his The Fall of Constantinople 1453 (1965) are still the most readable. For recent scholarship, Alexander Beecroft, An Ecology of World Literature (2015), and Anthony Kaldellis, The New Roman Empire: A History of Byzantium (Oxford UP, 2023), are good places to look.

Related Articles

• The Reign of Justinian I — the dynasty that defined Byzantine law and ambition
• Byzantine Iconoclasm — the century-long war over holy images
• The Macedonian Dynasty — the golden age of Byzantium
• The Fall of Constantinople — the end of an empire
• Byzantine Emperors: A Study of Power — the men who ruled the state
• The Nika Riots of 532 AD — the revolt that nearly toppled Justinian
• The Battle of Manzikert — the disaster that lost Anatolia
• The Battle of Yarmouk — the defeat that lost the southern provinces
• The Fourth Crusade and the Sack of Constantinople — the event that broke the empire
• Empress Theodora: Power Behind the Throne — the woman who saved an empire
• The Theme System: Byzantine Military Organization — the administrative innovation that saved Byzantium
• Byzantine Religion and the Orthodox Church — the religious dimension