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History of the Byzantine Empire (Byzantium)

Hagia Sophia
The Hagia Sophia is a domed monument built as a cathedral and is now a museum in Istanbul, Turkey. (Image credit: <a href="">Tatiana Popova</a> | <a href="">Shutterstock</a>)

The Byzantine Empire, also called Byzantium, was the eastern half of the Roman Empire, based at Constantinople (modern-day Istanbul) that continued on after the western half of the empire collapsed.

Byzantium continued on for nearly a millennium until Constantinople itself fell in a siege carried out by the Ottoman Empire in 1453. The golden age of the empire came during the reign of Justinian (A.D. 527-565) during which the empire’s territories extended as far as Western Europe, and the emperor’s builders constructed the Hagia Sophia, a great cathedral that still stands today.

Throughout their history, the people of Byzantium continued to refer to themselves as “Romans” writes Timothy Gregory, a professor at Ohio State University, in his book “A History of Byzantium” (Wiley-Blackwell, 2010).

They referred to themselves as Romans even though the Byzantines rarely controlled Rome, spoke mainly Greek, and in A.D. 1204 were betrayed when crusaders from the west sacked Constantinople in an attempt to gain money.


Constantine I took control of the Roman Empire after winning the Battle of the Milvian Bridge in October of A.D. 312. The events before the battle are steeped in legend, but Constantine is said to have had some sort of religious experience that resulted in his warming to Christianity. Gregory notes that he was baptized shortly before his death in A.D. 337.

Gregory notes that Constantine brought in a number of important changes that laid the foundations for the Byzantine Empire.

“The most significant of these changes were the emergence of Christianity as the favored (and then the official) religion of the state and the creation of Constantinople as the new urban center of the empire on the shores of the Bosphorus, midway between all the empire’s frontiers,” he writes.

Constantinople was built on the site of Byzantium, an urban center that had a long history of prior occupation. The writer Sozomen, who lived in the fifth century A.D., claimed that Constantine’s choice of location for his new city was inspired by God.

Constantine's death led to a series of short-lived successors. Theodosius I, who died in A.D. 395, was the last sole Roman emperor. After his death, the empire was split in two, the western half collapsing within a century but the eastern half living on and thriving, becoming what we call Byzantium.

Justinian I

Justinian I became emperor in 527. While it is said that the golden age of Byzantium occurred during his reign Justinian's rule certainly did not start off as golden. He came to power because he was the nephew, and adopted son, of his uncle, Justin I, a palace soldier who had usurped the throne.

In 532, just five years into his rule, Constantinople was hit by the Nika riots (Nika means “victory” or “conquer”). The ancient wrier Procopius (who lived in the sixth century A.D.) wrote that Constantinople, along with other imperial cities, was split into two factions called the “blue” and the “green,” which tended to take out their rivalry at the racetrack.

Byzantine authorities arrested members of the factions and sentenced them to be executed. That’s when the riot broke out; the rioters were angry with Justinian for the arrests, as well as the high taxes he imposed, and tried to overthrow him. 

The “members of the two factions conspiring together and declaring a truce with each other, seized the prisoners and then straightway entered the prison and released all those who were in confinement there … Fire was applied to the city as if it had fallen under the hand of an enemy …” wrote Procopius.

(From History of the Wars, I, xxiv, translated by H.B. Dewing, Macmillan, 1914 through Fordham University Website)

Justinian had to call in troops to put down the rioters, but he took advantage of the situation to build something grand. At the site of a destroyed church called the Hagia Sophia (“Holy Wisdom”) he would have a new, far grander, cathedral built.

Hagia Sophia’s dimensions are formidable for any structure not built of steel,” writes Helen Gardner and Fred Kleiner in their book "Gardner’s Art Through the Ages: A Global History." “In plan it is about 270 feet (82 meters) long and 240 feet (73 meters) wide. The dome is 108 feet (33 meters) in diameter and its crown rises some 180 feet (55 meters) above the pavement.”

After it was built, Justinian is said to have remarked “Solomon, I have outdone thee.”

In addition to building an incredible cathedral, Justinian oversaw a major territorial expansion of the empire, winning back territory in North Africa, Italy (including Rome), and parts of Western Europe. [Related: Stunning Byzantine Mosaic Uncovered in Israel]

The intellectual achievements of Justinian’s reign were also great and carry on to present day. “Art and literature flourished under his rule, and his officials carried out a remarkably thorough synthesis of Roman law that has served as the basis of the legal systems of much of Europe up to the present day,” writes Gregory.

In AD 541/542 a plague tore into Justinian’s empire, inflicting the emperor himself, although he survived. However, “many of his compatriots did not, and some scholars have argued that as much as one-third the population of Constantinople perished,” writes Gregory, noting that the disease would re-occur roughly every 15 years into the seventh century.

The spread and impact of the plague may have been aided by a food shortage brought about by cooler weather conditions. Recent research suggests that the passing of Halley’s comet in A.D. 536 blanketed the Earth, resulting in lower temperatures. It has also been suggested that a volcanic eruption in El Salvador contributed to the cooler weather.

By 1025, the Byzantine Empire stretched across modern-day Turkey, Greece and the Balkans. (Image credit: Cplakidas / Creative Commons.)

The Byzantine Dark Age

The centuries after Justinian’s death are sometimes referred to as the Byzantine “Dark Age” and for good reason, as a series of misfortunes befell the empire.

In the west, much of the territory that Justinian had captured was lost. By the beginning of the seventh century, “much of Italy was under Lombard rule, Gaul was in Frankish hands and the coastal regions of Spain, the final acquisition of Justinian’s re-conquest, were soon to fall to the Visigoths,” writes Andrew Louth, a professor at Durham University, in a chapter of the book “The Cambridge History of the Byzantine Empire” (Cambridge University Press, 2008).

He also notes that between 630 and 660 much of the empire’s eastern territory (including Egypt) would be lost to the Arabs. This put the empire in a bad spot.

“This radical upheaval, together with the persistent aggression of the Arabs against the remaining Byzantine lands and the incursions of Slavs and peoples hailing from the central European steppe into the Balkans, accelerated the transition of the cities of the eastern Mediterranean world that was already well underway,” writes Louth.

“By the end of the (seventh) century the cities had lost much of their social and cultural significance and survived as fortified enclaves,” used also for markets he writes. “Even Constantinople barely survived, and did so in much reduced circumstances.”

These difficult times perhaps contributed to iconoclasms that occurred in the eighth and ninth centuries A.D. During these periods, much Byzantine religious artwork was destroyed in fear that they were heretical. 

Byzantine comeback?

Byzantium never returned to the “golden age” it had reached during Justinian’s rule. Nevertheless, the military situation stabilized in the ninth century and by the 11th century, Byzantium had gained back a considerable amount of territory that it had lost.

By the time of the death of Emperor Basil II in December 1025, after a reign of almost 50 years, Byzantium was “the dominant power of the Balkans and Middle East, with apparently secure frontiers along the Danube, in the Armenian highlands and beyond the Euphrates,” writes Michael Angold, a professor at the University of Edinburgh, in a separate chapter of “The Cambridge History of the Byzantine Empire.” Additionally, they had succeeded in spreading Christianity to the north.

Angold notes that this comeback, of sorts, was tenuous to say the least. “Fifty years later, Byzantium was struggling for its existence. All its frontiers were breached,” he writes. By this time, nomads were entering Turkey and the Danube provinces, while the Normans had seized its Italian territories.

Nevertheless, the empire would regain some semblance of stability and continue on until it was hit with another blow in 1204.

Here, a huge mosaic with geometric patterns that dates back to the Byzantine Period and would have been used as the floor of a public building in what is today Kibbutz Bet Qama, in the B'nei Shimon region council in Israel. (Image credit: Yael Yolovitch, Israel Antiquities Authority)

The Fourth Crusade

A pivotal moment in the history of the Byzantine Empire occurred in 1204, when an army of crusaders from the west sacked Constantinople and installed a short-lived line of rulers to rule it. The idea of Christians crusading against other Christians was strange even by the standards of the Middle Ages.

There are a number of reasons why it came to this. An important reason is that in the decades preceding the sacking, the Byzantines had become estranged from their former allies in the west. The Orthodox Church broke away from the church in Rome in 1054 and, perhaps most importantly, people from the west were massacred in Constantinople in 1182, partly in response to the growing influence of western merchants and kingdoms.

This meant that in 1203, when a group of cash strapped crusaders were looking for money to finance an expedition to Egypt, they were willing to hear out Prince Alexius Angelos, a claimant to the Byzantine throne, who encouraged them to journey to Constantinople before going to Egypt.

If “they helped to reinstate him in Constantinople he would pay them 200,000 marks, give them all the supplies they needed and provide an army of 10,000 men. He would also place the Greek Orthodox Church under the authority of the papacy,” writes Jonathan Phillips, a professor at the University of London, in an article in History Today.

Phillips notes that by this time, the Byzantine military was in bad shape. “The death of Emperor Manuel Comnenus (1143-80) presaged a series of regencies, usurpations and coups. Between 1180 and 1204 no fewer than fifty-eight rebellions or uprisings took place across the empire.”

When the crusaders succeeded in taking the city in 1204, they sacked it and put a new line of “Latin” kings from the west on its throne. These rulers would remain in place until a Greek general named Michael Palaeologus re-took Constantinople and crowned himself Michael VIII (reign 1259-1282).

The end of the Byzantine Empire

While Constantinople was once again under control of a Greek ruler, its end was drawing near. The empire struggled on into the 15th century, the emperors gradually losing their importance in favor of religious officials. 

In 1395, Patriarch Anthony actually had to give a speech explaining why the Byzantine emperor was still important.

“The holy emperor has a great place in the church, for he is not like other rulers or governors of other regions. This is so because from the beginning the emperors established and confirmed the [true] faith in all the inhabited world…” it read in part.

(From the book Byzantium: Church Society, and Civilization Seen through Contemporary Eyes, University of Chicago Press, 1984, through Fordham University website)

In 1453, after a siege, the growing Ottoman Empire took Constantinople, putting an end to the empire. When the Ottomans examined the Hagia Sophia, which had been built nearly 1,000 years earlier, they were amazed.

“What a dome, that vies in rank with the nine spheres of heaven! In this work a perfect master has displayed the whole of the architectural science,” wrote Ottoman historian Tursun Beg (from a 2005 British Archaeological Reports series book by Elisabeth Piltz). They turned the Hagia Sophia into a mosque, adding four minarets that rise more than 200 feet (60 meters) off the ground.

Today, although the Byzantine Empire is long gone, the city of Constantinople (now called Istanbul) flourishes and is still regarded as a crossroads, both literally and metaphorically, between Europe and Asia.  

Owen Jarus

Owen Jarus
Owen Jarus writes about archaeology and all things about humans' past for Live Science. Owen has a bachelor of arts degree from the University of Toronto and a journalism degree from Ryerson University. He enjoys reading about new research and is always looking for a new historical tale.