Why Did Byzantine Empire Survive For So Long

Why Did Byzantine Empire Survive For So Long


Byzantines saw their conflict with Islam as a “conflict of civilizations” between traditional Roman world and a desert menace. But at first, this was not actually the case. Whereas Muslims had, from the start, separated the world into dar al-Islam (“Land of Islamd”) and dar al-harb (“House of War”), from Roman point of view, the conflict was a confrontation between a civilized society and uncivilized barbarians, the “godless Saracens”. Only from late eighth and early ninth century does a nuanced understanding of Islam develop in the Roman world, and only in the ninth century is Islam understood as an existential threat to the Roman Empire. Roman identity itself was highly religious, with expansion of Islam reducing the Empire to areas with almost exclusively Orthodox Christian population. This identity was a key for resistance to invasion, with Arab conquest having taken almost exclusively the areas where this identity was weak.

7th Century Collapse

In the year 565., the Roman (“Byzantine”) Empire stretched from Spain to Persia. By year 650., it was confined to Anatolia, Aegean Islands and a few enclaves in the Balkans. Having lost Egypt, Syria, Balkans and Africa, its revenues had fallen to only 1 million solidi – Ummayad Caliphate, which had conquered the richest Roman provinces, had an income of 4 million solidi. This allowed it to maintain continuous and consistent attacks on the Roman Anatolia. Consequence of constant attacks was abandonment of many urban centres and fortification of others, leading to a significant reduction in a degree of urbanization. In 655., the Caliphate attempted to conquer Constantinople, but the attack failed. As a result, Caliph Uthman was murdered in 656., leading to a civil war (fitna), which allowed the Empire some time to consolidate what remained under its control.

map of the initial Muslim invasions
Initial expansion of Islam

Constans went to secure Sicily and North Africa in 662., which Muslims exploited by mounting yearly raids into Anatolia. Constans himself was assassinated on Sicily for ignoring the threat to the capital, and when Mu’awiya marched towards the Constantinople, Armenians rebelled in 668., though the rebellion quickly ceased with death of Armenian commander Saborius. Siege of Constantinople was defeated, and in 674. the Romans had defeated Arab armies on land and on sea. By 678., Mu’awiya had to sue for peace due to problems within the Caliphate, but in Europe Romans had to accept existence of Bulgarian state around Danube after Bulgarian victory. In Africa, Muslims advanced not by military but through religious conquest – as Berber tribes gradually accepted Islam, nearby Roman fortresses fell to the conquerors. In Anatolia, Armenian princes played a ping-pong, switching between Roman and Arab rule. Bulgars invaded the Empire after murder of Emperor Justinian and his sons, while Arabs continued their advance in Anatolia. Empire meanwhile saw further two emperors (Anastasius and Theodosius III.) before Leo took the throne and organized the defences of the capital. Arab armies were harassed on their way through Anatolia, and the siege of capital failed. From then on, Arabs would abandon the attempts to take Constantinople, and instead focused on wearing out the Empire through constant raids.

Structural Reasons for Survival

Beliefs and Identity

In Byzantine Empire, emperors drew their legitimacy from the people, to an extent even greater than today’s democracies. While formally absolute, power of the Emperor was in reality constrained by various mechanics, but primarily by the Senate, the army and the people. One of primary symbols of imperial authority was acclamation by citizens of Constantinople. General Leontius in 695. and Isaac Angelos in 1185. used popular support to claim the throne. In 642., general Valentine abandoned his attempt at a coup when people rose up against him, and in a repeat attempt in 644.-645. he was killed. In 944., popular support allowed Constantine VII to retain the throne in face of an attempted coup by Lakapenes. In 963., Joseph Bringas was overthrown when people of the capital engaged his troops and opened the city doors to Nicephoros II. Phocas. Michael VI abdicated due to a lack of popular support, and Michael VII lost his throne after citizens had decided in favor of Bryennos.

Nikephoros II Phokas
Nikephoros II Phokas

In general, citizens of the Empire, and Constantinople in particular, were well-informed, cynical of their own rulers, and quick to act. As a result, Imperial legitimacy was dependant on popular support, which could be withdrawn at any time. Popularity could determine the ruler: Andronikos Komnenos became an emperor due to will of the people. Earlier, the ascension of Basil I had been post-facto justified by will of the people. In Byzantine Empire, remaining on the throne was akin to holding a wolf by the ears.

As the follow-up article (for the next week) is concerned primarily with the thematic era of Byzantine army – 7th to 11th centuries – the impact of provincial armies must be taken into account. Any rebels or pretenders to the throne had to secure support in the provinces, which were the only source of military power not directly under control of the Emperor, and early in existence of the system, were the only source of military power, period. But thematic armies were deeply rooted into the local society, and fortified cities could (and occasionally did) reject imperial authority by virtue of having city walls. As a result, individual cities and individual themes made their own choices as to whether to rebel against the central authority or not; as important as common Roman identity was, it was still often outweighted by the local identity.

Byzantine Empire’s themata in 750 AD

Local elites thus had a significant role in maintaining loyalty of local populations. While populations may have accepted Muslim rule, this lasted only for so long as the invading army was present. And because the Caliphate had identified itself around Islam, the Orthodox Christian identity of population was key in resisting the invasions.

Orthodoxy is closely linked to fate of the Empire, and thus the emperors usually try to be good Orthodox Christians. The main exceptions to this rule happened during the 7th century, when major military defeats were taken as a sign of God’s displeasure, thus opening doors for several heretical emperors. But by 7th century, the Church had closely interweaved itself with the Empire, providing both the state and the society at large moral strength required for survival. Worship of saints and martyrs provided common point which connected different areas and groups within the Empire, with the Virgin Mary being especially important. This also meant that heresy was treated as treason, and persecuted by the state apparatus.

The early success of Muslim invasion was also in large part caused by issues of identity. Quick loss of Syria was a consequence of long Persian occupation, which meant that the already very heterogenous (and largely heretic) population no longer identified with the Empire. Abandoned by the Empire and ignored by the Persia, they got used to self-rule, making them resent intrusive Roman administration when it returned.

In the areas of the Empire that did not fall to invaders, Roman community and identity were based on Roman and canon law. Laws were based on tradition, and thus created a framework which reinforced Christian Roman identity and introduced widely accepted norms. Common law was heavily influenced by the Church, which increased reach of the state while at the same time increasing role of the Church.

Romans saw the Arabs as godless barbarians, hostile to Christianity and any sort of civilization. Muslims reinforced this, as they saw Orthodox Christians with suspicion and engaged in regular pogroms as well as occasional slaughters. All of this helped define the Empire as highly Christian, as well as motivate the active resistance. Religious and national consciousness, proximity of Constantinople and presence of the army all combined to make population of Anatolia highly prone to either resisting or avoiding Arab invasions.


Social elites of the Empire had experienced a deep change in character with Arab invasions. The old “international” elite had disappeared alongside the associated world, to be replaced by the pseudo-merocratic elite of diverse social background. This new elite was roughly divided into court bureocrats with major landholdings in multiple provinces, and landed military aristocracy whose holdings were usually concentrated in a single province. There was however some overlap between the two, and with the state having a monopoly on armed force, new militarized provincial elite also often had interests in the capital. All of this meant that military service, especially in the guards, was a good way of improving one’s social position.

Importance of military was seen in the process of acclamation

Society had also decentralized and localized under pressure, and inhabitants usually looked to safeguard their own settlement first and foremost. At the same time, provincial armies of the themata had deep connections to local society, with many rebellions being expressions of local interests (soldiers of the themes had even entered and plundered Constantinople itself in 698. and 715.). Roman identity overpowered regional identities only when army, Church and/or provincial elites were present and active; otherwise, regional identities overshadowed Roman one. Resistance was also highly dependent on ethnic consciousness. Largely Greek Anatolia had resisted invasion, while in conquered Syria the Greeks had escaped to Anatolia while indigenous population had calmly accepted Arab rule.

Government required cooperation of local elites to maintain its authority, but this was not certain. Therefore, Constantinople’s authority was safe only in areas where its ability to intervene militarily was unquestioned – primarily in Anatolia. But threat alone was not enough, which is why religious dogma was also a highly political question: challenges to religious dogma were challenges to the government as such. North Africa and Italy were always independent of the government in Constantinople, and as the central government was forced to focus onto Anatolia, their practical independence grew. Still, elites in Italy and Sicily remained loyal to government in Constantinople, and so Sicily remained part of the Empire until the 9th century.

Elites however could also be dangerous for the Empire. There was no one homogenous mass, but interests of the bureocratic urban nobility from the capital diverged significantly from those of provincial military aristocracy. Both groups remained loyal to Constantinople, which was a source of status, privileges and riches, but they were also in direct competition for the same. Moreover, both groups wanted to intrude onto other group’s terrain. This led to Constantinople’s urban elites acquiring – often forcibly – the nominally protected military lands, directly weakening the Empire’s military strength. Attempts of various emperors to protect the Empire’s system of military lands achieved only limited success, and ceased entirely after Basil II’s death in 1025. As a result, only a fraction of the Empire’s nominally available soldiers were actually capable of serving in combat. This along with changing strategic picture since 10th century led the Empire to rely more and more on mercenaries – but these were expensive, and added expenses arrived precisely at the time when elites were busy evading taxes while also ruining the imperial tax base of small landowners.

Even worse was direct political infighting. Provincial aristocracy had achieved its status based on wealth acquired in warfare; and while they did attempt to feudalize the Empire and turn imperial troops into their personal retinues, landed magnates were also invested into maintaining the army that was the basis of their power. This however made the army a threat to the court faction, which led to catastrophic consequences. In 1053., Constantine IX, with support of the court faction, disbanded the 50 000 strong “Iberian Army”. This left the Anatolia vulnerable to invasions from the East as there were no other combat-effective provincial forces left. By 1073., the Empire was a paper tiger. Finally, strenghtening of the elites had shown itself in increased separatism, with Cyprus gaining independence in 1185. and Trebizond in 1203.

Iberian Themes


Geography had played a key role in the Empire’s survival. Mountains of Taurus and Anti-Taurus were a major obstacles, allowing Roman forces in northern Syria and Cylicia avenue of retreat when necessary. Mountains themselves had few passes that were easily defended, and the land beyond had a climate that Arabs were not used to. As a result, Romans had managed to hold onto the northern Syria and Cylicia up until the early eighth century, and Arabs never made any permanent conquests in Anatolia – that would only happen when Turks arrived. While the Caliphate had tried to conquer Anatolia from 660s onwards, by that time the Roman Empire had restructured the army, as well as adapted the defense strategy, focusing on harrassment and defense of fortified positions while abandoning set-piece battles. This led to attempts at conquest of Constantinople, but from 680s onwards Arabs abandon deep incursions and instead focus on destroying border defences and maintaining status quo.

Constantinople itself was also a major factor. Its location allowed it to block any transit from Europe to Asia Minor, as well as transit from Mediterranean to the Black Sea. More importantly, it also allowed Constantinople to act as the Empire’s primary logistical basis.

Climate and Demographics

Climate also plays a crucial role in development of societies, especially premodern societies. Period of global warming had dominated Roman era up until 2nd century AD, which allowed development of agriculture and animal husbandry. After 2nd century, climatic instability replaced until-then favorable climate, which may be connected to weakening of the Roman Empire. And in 530s, Little Ice Age entered, also potentially bringing with it the Justinianic Plague.

During the sixth and seventh centuries, Anatolia had wetter climate, which changed into drier and colder climate beginning with mid-seventh century. Wars also likely had a major impact, as many cities and towns were destroyed by Arabs during the seventh century. Many of surviving settlements were simply abandoned, while those that remained were much reduced in size and provided with fortifications. Economy changed in focus to grains and livestock, which was helped by the now wetter climate during 6th to 8th centuries in northern and central Anatolia.

Climate played a massive role in fortunes of the Empire. Volcanic eruption of 536 AD had caused the “Little Ice Age”, which weakened the Empire and left it open to conquest. Recovery of the Empire and its expansion phase lasted from 9th to 11th centuries, which is a period of wet climate in Anatolia. In 12th century, drying of climate pushed Seljuks to migrate into Anatolia, and also caused internal political instability within the Empire. Fall of Constantinople in 1204. also happened after a long period of dry and cold climate in 12th century, while western Anatolia was lost 50 years later – concurrently with global cooling following the 1257. volcanic eruption of Samalas. Such events also caused disastrous events that may not have been immediately obvious: massive hunger which affected the Empire in years 920 – 930 AD had caused the small landowners to sell their land to magnates, which in a single stroke destroyed both the tax base of the Empire and the recruitment base of its army.


Early in the Middle Ages, Byzantine Empire didn’t have much trade, being preoccupied with survival against the Arab invasions. However, with time trade developed, as well as trade relations with other states. But relations with Venice in particular helped to weaken the Empire, with the Empire first admitting Venetian independence in 875., and establishing marriage ties in 1005., which allowed the Empire to maintain influence in the Adriatic.

By 11th century, need to ensure cooperation of Venice at all costs meant that the Empire had to give Venice a Golden Bull, as well as other trade concessions. The result of this was complete economic dominance of Venice in the eastern Mediterranean. By the time John II had tried to reestablish Empire’s economic sovereignty, Byzantium had weakened so much that Venice was able to enforce a favorable treaty. By 12th century, Venice had taken over many of the Empire’s trade activities.

Empire’s economy was also structurally weak, as all economic activity outside the agriculture was concentrated in Constantinople, which allowed the government a high degree of control. Traders were dependant on the state, preventing natural development of Byzantine trade. By contrast, foreign (such as Venetian) traders faced none of the restrictions and obstacles that Byzantine traders did. The end result was that the Empire had, essentially, committed an economic suicide.


After losing Syria and Egypt during first wave of Muslim conquests, the Empire had lost majority of its resources and economy – yet the army could not be reduced in proportion to the losses in resources. Surviving field armies were pulled back and quartered in Anatolia, with soldiers receiving military lands to supplement the much-reduced wages. With this, the army transformed into a kind of Home Guard, with soldiers having “day jobs” – specifically, being landlords – with which they financed their needs.

With the former recruiting grounds in Balkans having been lost during the 7th century, it was Anatolia and Armenia which were now the primary source of new recruits. While foreigners were still used as mercenaries, the core of the army were now native Greeks and Armenians, who accounted for vast majority of the troops from 7th to 11th centuries.

In order to protect himself from rebellion by territorial (thematic) forces, Constantine V introduced the tagmata – fully professional, standing units in direct service of the Emperor. During the 9th century, number of these units gradually increased, as did the number of specialist and mercenary units while the strength of thematic forces gradually depleted. Main cause of this was the shift to offensive posture as the Caliphate weakened, and during the 11th century number of foreigners in the army increased massively. The trend only reinforced itself after the loss of central Anatolia in 1070s deprived the Empire of its primary recruiting ground. But already in 1040., western Anatolia was completely denuded of any effective military capabilities, and by late 11th century army was comprised entirely of mercenaries.

The Empire attempted to counteract this by increasing recruitment from its European provinces, but the fact that these were now largely ethnically Slavic made them unsuitable for mass recruitment (with the exception of Greece proper and maybe Albania). As a result, primary source of new recruits were foreign mercenaries, and this remained true despite – in some cases almost successful – attempts by Komnenian emperors at restoring the native military. After losses of 1204., Byzantine army changed into a mixture of different structures, and by the late 13th century it had completely lost any serious offensive capability. During the rule of Paleologs, only one third of troops were ethnic Byzantines, while the remainder were foreign mercenaries. This resulted in regular disasters, such as the conquest of Athens by the Catalan company (6 000 mercenaries strong) in 1304.

Civilians also participated in defense of their cities. After 7th century, the Empire, for the first time in its history, introduced organized militia units. From 9th century onwards, defense of Constantinople consisted of a mixture of professional military and civilian militia. Other cities also had such organizations which, while not approved, were at least tolerated by the central government.


Byzantine experiences show that excessive centralization is as dangerous as excessive decentralization. Former makes the country too reliant on (in)competence of the central government, while the latter makes coordination difficult to impossible. Thematic system proved to be so successful because it represented, for Byzantine conditions, an ideal balance of centralization and decentralization. It provided the Empire with a relatively cheap but very effective army of part-time professionals, while also stiffening the Empire’s military, social and political structure against both external and internal upheavals. It is no accident that the final slide into oblivion began as the system of thematic militia fell apart and the Empire had to rely on full-time professionals and mercenaries.

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