Decline and Revival

Soon after Justinian's death in 565, the Persian war was resumed. The southward migration of the Slavs, accompanied by the Avars, continued. A German tribe, the Lombards, occupied most of Italy; Byzantium retained control only of Ravenna and parts of the south.

In 610 Heraclius, son of a military governor, won the throne by force. During the early part of his reign the Persians advanced westward to the Mediterranean and invaded Asia Minor. While Heraclius was engaged in driving them back, the Avars and Slavs besieged Constantinople, but they were soundly defeated in 626. The next year Heraclius defeated the Persians.

Within a decade the Muslim Arabs had begun their conquests. Syria, Palestine, and Egypt were taken from the empire by 642, the rest of North Africa by the end of the century. Coming by sea, the Arabs besieged Constantinople-from 674 to 678, but the city's defenses held. Then the Bulgars invaded the empire in force, and in 680 part of what is now Bulgaria was ceded to them.

In 717 Arab land forces, already in possession of much of Asia Minor, were approaching the Byzantine capital. To meet the emergency, an energetic provincial governor, Leo (III), was elevated to the throne. Well prepared by Leo, Constantinople withstood a long siege by both land and sea forces. In 741 Leo finally expelled the Arabs from western Asia Minor. Within the empire Leo started a long religious conflict by his policy of iconoclasm—banning the use of icons (sacred images)—in the Eastern Church. The policy antagonized the Roman Church, widening the religious division between the East and the West.

East Asia Minor was recovered from the Arabs, but Ravenna fell to the Lombards in 751. In 780 the widowed Empress Irene became regent for her young son, Constantine VI. In 787 Irene called the seventh ecumenical council of the Christian Church, at Nicaea, and had image-worship restored. Ten years later she deposed her son, had him blinded, and took the throne herself.

Pope Leo III crowned Charlemagne, king of the Franks, as Roman emperor in 800. The Byzantines ignored the implication that Charlemagne had authority in the East, but in 812 they recognized him as Western emperor, thereby acknowledging that the pope was no longer a subject of the Eastern emperor.

Leo V ascended the Byzantine throne in 813 and reinstated the policy of iconoclasm. It was not until 843, during the regency of the Empress Theodora, that image-worship was permanently restored. In the 860's a bitter disagreement over the appointment of Photius as patriarch arose between the Roman and Eastern churches, and Emperor Michael III repudiated the pope's claims of religious supremacy in the East.

Conflict with the Arabs and the Bulgarians was almost continuous and was interspersed with Slavic uprisings. Beginning in 827 the Arabs occupied Sicily and then southern Italy. In spite of the constant warfare, the empire regained its prosperity, learning revived, and a new era of magnificence developed. Under Basil I, 867-86, gains were made against the Arabs. New enemies, the Russians and Magyars, appeared to the north, but were successfully dealt with.

Nicephorus Phocas, a Byzantine general who became emperor by marrying the widowed empress, regained much imperial territory. Conquests continued under his successors. Basil II subdued the Bulgarians, 1004-18, and annexed their kingdom. Friendly relations were established with the Arabs in the Holy Land.