History of the Byzantine Empire
This history of the Byzantine Empire covers the history of the eastern Mediterranean empire from late antiquity until the Fall of Constantinople in 1453 AD. Several events from the 4th to 6th centuries mark the transitional period during which the Roman Empire's east and west divided. In 285, the emperor Diocletian (r. 284–305) partitioned the Roman Empire's administration into eastern and western halves. Between 324 and 330, Constantine I (r. 306–337) transferred the main capital from Rome to Byzantium, later known as Constantinople (""City of Constantine"") and Nova Roma (""New Rome""). Under Theodosius I (r. 379–395), Christianity became the Empire's official state religion and others such as Roman polytheism were proscribed. And finally, under the reign of Heraclius (r. 610–641), the Empire's military and administration were restructured and adopted Greek for official use instead of Latin. Thus, although it continued the Roman state and maintained Roman state traditions, modern historians distinguish Byzantium from ancient Rome insofar as it was oriented towards Greek rather than Latin culture, and characterised by Orthodox Christianity rather than Roman polytheism.The borders of the Empire evolved significantly over its existence, as it went through several cycles of decline and recovery. During the reign of Justinian I (r. 527–565), the Empire reached its greatest extent after reconquering much of the historically Roman western Mediterranean coast, including north Africa, Italy, and Rome itself, which it held for two more centuries. During the reign of Maurice (r. 582–602), the Empire's eastern frontier was expanded and the north stabilised. However, his assassination caused a two-decade-long war with Sassanid Persia which exhausted the Empire's resources and contributed to major territorial losses during the Muslim conquests of the 7th century. In a matter of years the Empire lost its richest provinces, Egypt and Syria, to the Arabs.During the Macedonian dynasty (10th–11th centuries), the Empire again expanded and experienced a two-century long renaissance, which came to an end with the loss of much of Asia Minor to the Seljuk Turks after the Battle of Manzikert in 1071. This battle opened the way for the Turks to settle in Anatolia as a homeland.The final centuries of the Empire exhibited a general trend of decline. It struggled to recover during the 12th century, but was delivered a mortal blow during the Fourth Crusade, when Constantinople was sacked and the Empire dissolved and divided into competing Byzantine Greek and Latin realms. Despite the eventual recovery of Constantinople and re-establishment of the Empire in 1261, Byzantium remained only one of several small rival states in the area for the final two centuries of its existence. Its remaining territories were progressively annexed by the Ottomans over the 15th century. The Fall of Constantinople to the Ottoman Empire in 1453 finally ended the Empire.During the 3rd century, three crises threatened the Roman Empire: external invasions, internal civil wars and an economy riddled with weaknesses and problems. The city of Rome gradually became less important as an administrative centre. The crisis of the 3rd century displayed the defects of the heterogeneous system of government that Augustus had established to administer his immense dominion. His successors had introduced some modifications, but events made it clearer that a new, more centralized and more uniform system was required.Diocletian was responsible for creating a new administrative system (the tetrarchy). He associated himself with a co-emperor, or Augustus. Each Augustus was then to adopt a young colleague, or Caesar, to share in the rule and eventually to succeed the senior partner. After the abdication of Diocletian and Maximian, however, the tetrachy collapsed, and Constantine I replaced it with the dynastic principle of hereditary succession.Constantine moved the seat of the Empire, and introduced important changes into its civil and religious constitution. In 330, he founded Constantinople as a second Rome on the site of Byzantium, which was well-positioned astride the trade routes between East and West; it was a superb base from which to guard the Danube river, and was reasonably close to the Eastern frontiers. Constantine also began the building of the great fortified walls, which were expanded and rebuilt in subsequent ages. J. B. Bury asserts that ""the foundation of Constantinople [...] inaugurated a permanent division between the Eastern and Western, the Greek and the Latin, halves of the Empire—a division to which events had already pointed—and affected decisively the whole subsequent history of Europe.""Constantine built upon the administrative reforms introduced by Diocletian. He stabilized the coinage (the gold solidus that he introduced became a highly prized and stable currency), and made changes to the structure of the army. Under Constantine, the Empire had recovered much of its military strength and enjoyed a period of stability and prosperity. He also reconquered southern parts of Dacia, after defeating the Visigoths in 332, and he was planning a campaign against Sassanid Persia as well. To divide administrative responsibilities, Constantine replaced the single praetorian prefect, who had traditionally exercised both military and civil functions, with regional prefects enjoying civil authority alone. In the course of the 4th century, four great sections emerged from these Constantinian beginnings, and the practice of separating civil from military authority persisted until the 7th century.Under Constantine, Christianity did not become the exclusive religion of the state, but enjoyed imperial preference, since the Emperor supported it with generous privileges: clerics were exempted from personal services and taxation, Christians were preferred for administrative posts, and bishops were entrusted with judicial responsibilities. Constantine established the principle that emperors should not settle questions of doctrine, but should summon general ecclesiastical councils for that purpose. The Synod of Arles was convened by Constantine, and the First Council of Nicaea showcased his claim to be head of the Church.The state of the Empire in 395 may be described in terms of the outcome of Constantine's work. The dynastic principle was established so firmly that the emperor who died in that year, Theodosius I, could bequeath the imperial office jointly to his sons: Arcadius in the East and Honorius in the West. Theodosius was the last emperor to rule over the full extent of the empire in both its halves.The Eastern Empire was largely spared the difficulties faced by the West in the third and fourth centuries, due in part to a more firmly established urban culture and greater financial resources, which allowed it to placate invaders with tribute and pay foreign mercenaries. Throughout the fifth century, various invading armies overran the Western Empire but spared the east. Theodosius II further fortified the walls of Constantinople, leaving the city impervious to most attacks; the walls were not breached until 1204. To fend off the Huns of Attila, Theodosius gave them subsidies (purportedly 300 kg (700 lb) of gold). Moreover, he favored merchants living in Constantinople who traded with the Huns and other foreign groups.His successor, Marcian, refused to continue to pay this exorbitant sum. However, Attila had already diverted his attention to the Western Roman Empire. After he died in 453, his empire collapsed and Constantinople initiated a profitable relationship with the remaining Huns, who would eventually fight as mercenaries in Byzantine armies.