Survival, 565–717

In the early 7th century the Avars and later the Bulgars overwhelmed much of the Balkans, threatening Constantinople from the west. Simultaneously the Persian Sassanids overwhelmed the Prefecture of the East and penetrated deep into Anatolia. Heraclius, son to the exarch of Africa, set sail for the city and assumed the purple. He found the military situation so dire that he is said at first to have contemplated withdrawing the imperial capital to Carthage, but relented after the people of Constantinople begged him to stay. While the Great City withstood a siege by 80,000 Avars and the Persian fleet, Heraclius launched a spectacular campaign into the heart of the Persian empire. The Persians were defeated outside Nineveh, and their capital at Ctesiphon was surrounded by the Byzantines. Persian resistance collapsed, and all the lost territories were recovered in 627. Heraclius replaced Latin with Greek as the language of government, law and military command.

However, the unexpected appearance of the newly-converted and united Muslim Arabs took the Empire by surprise, and the southern provinces were overrun. Constantinople was besieged twice by the Arabs, once in a long blockade between 674 and 678, and once again in 717. The second Arab siege was laid by both land and sea. The Arab ground forces, led by Maslama, were met with the city's impregnable walls, the stout resistance of the defenders, freezing winter temperatures, chronic outbreaks of disease, starvation, and ferocious Bulgar attacks on their camp. Meanwhile, their naval fleet was decimated by the newly-devised Greek Fire of the Byzantine navy, and its remnants were subsequently utterly destroyed in a storm on the return home. The crushing victory of the Byzantines was a severe blow to Caliph Umar II, and the expansion of the Umayyad Caliphate was severely stunted during his reign.

Recovery, 717–1025
Emperor Leo IV (886–912) adoring Jesus Christ. Mosaic in the Hagia Sophia.
Emperor Leo IV (886–912) adoring Jesus Christ. Mosaic in the Hagia Sophia.

For the Byzantines, the victory at Constantinople was an epic triumph. A long period of Byzantine retreat and stagnation came to an end, and the imperial frontier in the east became fixed on the Taurus and Anti-Taurus mountain ranges in eastern Asia Minor, where it would remain unchanged for the next two hundred years.

Asia Minor became the heartland of the empire, and from this time onwards the Byzantines began a recovery that resulted in the recovery of parts of Greece, Macedonia and Thrace by the year 814. By the early years of the eleventh century, the Bulgarians had been utterly destroyed and annexed to the empire, the Slavs and the Rus' had converted to Orthodoxy. In Italy, the emperor Basil I (867-886) reconquered the whole of the south, restoring Byzantine power to a position stronger than at any time since the seventh century.

In the east, the imperial armies began a major advance during the tenth and eleventh centuries, resulting in the recovery of Crete, Cyprus, Cilicia, Armenia, eastern Anatolia and northern Syria, and the reconquest of the holy city of Antioch.
The Iconoclast controversy, 730–787, 814–842

In the eighth and ninth centuries the iconoclast movement caused serious political unrest throughout the Empire. The emperor Leo III issued a decree in 726 against images, and ordered the destruction of a statue of Christ over one of the doors of the Chalke, an act which was fiercely resisted by the citizens. Constantine V convoked a church council in 754 which condemned the worship of images, after which many treasures were broken, burned, or painted over. Following the death of his son Leo IV in 780, the empress Irene restored the veneration of images through the agency of the Second Council of Nicaea in 787.

The iconoclast controversy returned in the early 9th century, only to be resolved once more in 843 during the regency of Empress Theodora (9th century), who restored the icons. These controversies contributed to the deterioration of relations with the Roman Catholic Church and the Eastern Orthodox Church.

The Vikings, from 860

The Vikings (who knew the city as Miklagarð - the great city) couldn't resist the city's riches. In 860 they plundered Constantinople for the first time, setting fire to churches and houses, plundering and looting. The emperor was forced to offer gold for peace and later had to pay the Vikings annual tribute to avoid further plundering. There was little trust of the Vikings, if they wanted to trade in the city they had to go through a certain gate followed by the emperor's men, and they had to leave their weapons outside the city walls and couldn't enter with more than 50 at a time.[citation needed]

In 980 emperor Basil II received an unusual gift from Prince Vladimir I(Valdemar) of Kiev. He received an army of 6,000 Scandinavian-Russian Vikings which Basil incorporated into his own army as a single unit, which became known as the "The Axe-Wielding Guard"—after the huge axes they used in battle. Posterity knows this unit as the Varangians—the sworn. They were the best paid troops in the empire, they were allowed to keep any booty they managed to obtain from the battlefield and towns they conquered. They also had a right to "polutasvarv" (palace plundering) whenever the emperor died, in which they went through the palaces in the capital and grabbed all the treasures and valuables they could carry. [citation needed]The Varangians served the emperor for over 300 years.

Prelude to the Komnenian period 1025–1081

In the late eleventh century, catastrophe struck the Byzantine empire. With the imperial armies weakened by years of insufficient funding and civil warfare, Emperor Romanos IV Diogenes suffered a surprise defeat at the hands of Alp Arslan (sultan of the Seljuk Turks) at the Battle of Manzikert in 1071. Romanus was captured, and although the Sultan's peace terms were not excessive, the battle was catastrophic for the Byzantine Empire.

On his release, Romanus found that his enemies had conspired against him to place their own candidate on the throne in his absence. Romanus surrendered and suffered death by torture. The new ruler, Michael VII Ducas, refused to honour the treaty that had been signed by Romanus. In response, the Turks began to move into Anatolia in 1073, while the collapse of the old defensive system meant that they met no opposition. To make matters worse, chaos reigned as the empire's remaining resources were squandered in a series of disastrous civil wars. Thousands of Turkoman tribesmen crossed the unguarded frontier and moved into Anatolia. By 1080, an area of 30,000 square miles had been lost to the empire, and the Turks were within striking distance of Constantinople.

The Komnenoi 1081–1185
The Byzantine Empire under Manuel I, c. 1180.
The Byzantine Empire under Manuel I, c. 1180.

Under the Komnenian dynasty (1081–1185), Byzantium staged a remarkable military, financial and territorial recovery. This is sometimes called the Komnenian restoration, and is closely linked to the establishment of the new military system of this period.

In response to a call for aid from Alexios I Komnenos, the First Crusade assembled at Constantinople in 1096 and set out for Jerusalem. Much of this is documented by the writer and historian Anna Komnene in her work The Alexiad. The Crusaders agreed to return any Byzantine territory they captured during their advance. In this way Alexios gained territory in the north and west of Asia Minor. During the twelfth century Byzantine armies continued to advance, reconquering much of the lost territory in Asia Minor. The recovered provinces included the fertile coastal regions, along with many of the most important cities. By 1180, the Empire had gone a long way to reversing the damage caused by the Battle of Manzikert. Under Manuel Komnenos, the emperor had attained the right to appoint the King of Hungary, and Antioch had become a vassal of the empire.

With the restoration of firm central government, the empire became fabulously wealthy. The population was rising (estimates for Constantinople in the twelfth century vary from approximately 100,000 to 500,000), and towns and cities across the empire flourished. Meanwhile, the volume of money in circulation dramatically increased. This was reflected in Constantinople by the construction of the Blachernae palace, the creation of brilliant new works of art, and the general prosperity of the city at this time. It is possible that an increase in trade, made possible by the growth of the Italian city-states, may have helped the growth of the economy at this time. Certainly, the Venetians and others were active traders in Constantinople, making a living out of shipping goods between the Crusader Kingdoms of Outremer and the West while also trading extensively with Byzantium and Egypt. The Venetians had factories on the north side of the Golden Horn, and large numbers of westerners were present in the city throughout the twelfth century.
Twelfth century mosaic from the upper gallery of the Hagia Sophia, Constantinople. Emperor John II (1118–1143) is shown on the left, with the Virgin Mary and infant Jesus in the centre, and John's wife Piroska of Hungary on the right.
Twelfth century mosaic from the upper gallery of the Hagia Sophia, Constantinople. Emperor John II (1118–1143) is shown on the left, with the Virgin Mary and infant Jesus in the centre, and John's wife Piroska of Hungary on the right.

In artistic terms, the twelfth century was a very productive period in Byzantium. There was a revival in the mosaic art, for example. Mosaics became more realistic and vivid, with an increased emphasis on depicting three-dimensional forms. There was an increased demand for art, with more people having access to the necessary wealth to commission and pay for such work. According to N.H.Baynes (Byzantium, An Introduction to East Roman Civilization):

"With its love of luxury and passion for colour, the art of this age delighted in the production of masterpieces that spread the fame of Byzantium throughout the whole of the Christian world. Beautiful silks from the work-shops of Constantinople also portrayed in dazzling colour animals - lions, elephants, eagles, and griffins - confronting each other, or represented Emperors gorgeously arrayed on horseback or engaged in the chase."

"From the tenth to the twelfth century Byzantium was the main source of inspiration for the West. By their style, arrangement, and iconography the mosaics of St. Mark's at Venice and of the cathedral at Torcello clearly reveal their Byzantine origin. Similarly those of the Palatine Chapel, the [[Martorana at Palermo, and the cathedral of Cefalù, together with the vast decoration of the cathedral at Monreale, demonstrate the influence of Byzantium on the Norman Court of Sicily in the twelfth century. Hispano-Moorish art was unquestionably derived from the Byzantine. Romanesque art owes much to the East, from which it borrowed not only its decorative forms but the plan of some of its buildings, as is proved, for instance, by the domed churches of south-western France. Princes of Kiev, Venetian doges, abbots of Monte Cassino, merchants of Amalfi, and the Norman kings of Sicily all looked to Byzantium for artists or works of art. Such was the influence of Byzantine art in the twelfth century, that Russia, Venice, southern Italy and Sicily all virtually became provincial centres dedicated to its production."

The Palaeologi, 1204–1453
The Entry of the Crusaders into Constantinople, by Eugène Delacroix, 1840.
The Entry of the Crusaders into Constantinople, by Eugène Delacroix, 1840.

However, after the demise of the Comnenian dynasty at the close of the twelfth century, the Byzantine Empire declined steeply. Dynastic strife under the Angelid dynasty (1185–1204) culminated in the disastrous capture and sack of Constantinople by soldiers of the Fourth Crusade on 13 April 1204. At the end of the Comnenian dynasty, Constantinople had a population of 400,000 people, but by the time the Fourth Crusade arrived at Constantinople, the population had dropped to perhaps 150,000. For the next half-century, Constantinople was occupied by the forces of the so-called Latin Empire. During this time, the Byzantine emperors made their capital at nearby Nicaea, which became a resort for refugees from occupied Constantinople. From this base, Constantinople was liberated from its final Latin ruler, Baldwin II, by Byzantine forces under Michael VIII Palaeologus in 1261. By 1261 the population of the city may have fallen as low as 35,000. Besides the Empire of Nicaea, two other small states formed as a result of the Latin occupation in 1204: the Empire of Trebizond and Despotate of Epirus. After the liberation of Constantinople by the Palaeologi, the imperial palace of Blachernae in the north-west of the city became the main imperial residence, with the old Great Palace on the shores of the Bosporus going into decline. When the Ottoman Turks captured the city in 1453, the population was at 50,000 people.
Importance
Eagle and Snake, 6th century mosaic flooring ­Costantinople, Grand Imperial Palace
Eagle and Snake, 6th century mosaic flooring ­Costantinople, Grand Imperial Palace
Culture

Constantinople was the largest and richest urban centre in the Eastern Mediterranean during the late Roman Empire, mostly due to its strategic position commanding the trade routes between the Aegean and the Black Sea. After the fourth century, when Emperor Constantine I relocated his eastern capital to Byzantium, it would remain the capital of the eastern, Greek speaking empire for over a thousand years. As the capital of the Eastern Roman Empire (now commonly known as the Byzantine Empire), the Greeks called Constantinople simply "the City", while throughout Europe it was known as the "Queen of Cities." In its heyday, roughly corresponding to what are now known as the Middle Ages, it was the richest and largest European city, exerting a powerful cultural pull and dominating economic life in the Mediterranean. Visitors and merchants were especially struck by the beautiful monasteries and churches of the city, particularly Hagia Sophia, or the Church of Holy Wisdom. A Russian 14th-century traveller, Stephen of Novgorod, wrote, "As for St Sophia, the human mind can neither tell it nor make description of it". The cumulative influence of the city on the west, over the many centuries of its existence, is incalculable. In terms of technology, art and culture, as well as sheer size, Constantinople was without parallel anywhere in Europe for a thousand years.

Politics
Photo of a 15th Century map showing Constantinople in the upper left corner.
Photo of a 15th Century map showing Constantinople in the upper left corner.

The city provided a defence for the eastern provinces of the old Roman Empire against the barbarian invasions of the 5th century. The 18 metre (60 feet) tall walls built by Theodosius II (413-414) were essentially invincible to the barbarians who, coming from the Lower Danube, found easier targets to the west than the richer provinces to the east in Asia. From the 5th century the city was also protected by the Long Walls, a 60 kilometre chain of walls across the Thracian peninsula. Many scholars argue that these sophisticated fortifications allowed the east to develop relatively unmolested, while Rome and the west collapsed. With the emergence of Christianity and the rise of Islam, Constantinople became the veritable gates to Christian Europe that stood at the fore of Islamic expansion. As the Byzantine Empire was situated in-between the Islamic world and the Christian west, so did Constantinople act as Europe’s first line-of-defense against Arab advances in the 7th and 8th centuries. The city, and the empire, would ultimately fall to the Ottomans by 1453, but its enduring legacy had provided Europe centuries of resurgence following the collapse of Rome.

Architecture
Constantinople's monumental center.
Constantinople's monumental center.

The influence of Byzantine architecture and art can be seen in the copies taken from it throughout Europe. Particular examples include St. Mark's in Venice, the basilicas of Ravenna, and many churches throughout the Slavic East. Also, alone in Europe until the 13th century Italian florin, the Empire continued to produce sound gold coinage, the solidus of Diocletian becoming the bezant prized throughout the Middle Ages. Its city walls (the Theodosian Walls) were much imitated (for example, see Caernarfon Castle) and its urban infrastructure was moreover a marvel throughout the Middle Ages, keeping alive the art, skill and technical expertise of the Roman Empire.
Religious

Constantine's foundation gave prestige to the Bishop of Constantinople, who eventually came to be known as the Ecumenical Patriarch, vying for honour with the Pope.[7] They were often regarded as "first among equals", a situation which contributed to the Great Schism that divided Christianity into Western Catholicism and Eastern Orthodoxy from 1054 onwards (although the anathemas that each religious leader pronounced against the other have been withdrawn in recent times). The Patriarch of Constantinople is still today considered outstanding in the Orthodox Church, along with the Patriarchs of Alexandria, Antioch, Jerusalem, Moscow and the later Slavic Patriarchs. This position is largely ceremonial but still today carries great weight, particularly since by tradition Constantinople carries the administrative burden of the orthodox churches in 'barbarian lands'.