Byzantine Empire

The Byzantine Empire, also referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinople (modern Istanbul, formerly Byzantium). It survived the fragmentation and fall of the Western Roman Empire in the 5th century AD and continued to exist for an additional thousand years until it fell to the Ottoman Turks in 1453. During most of its existence, the empire was the most powerful economic, cultural and military force in Europe. "Byzantine Empire" is a term created after the end of the realm; its citizens continued to refer to their empire simply as the Roman Empire (Greek: Βασιλεία Ῥωμαίων, tr. Basileia Rhōmaiōn; Latin: Imperium Romanum), or Romania (Ῥωμανία), and to themselves as "Romans". Several signal events from the 4th to 6th centuries mark the period of transition during which the Roman Empire's Greek East and Latin West diverged. Constantine I ( r . 324–337) reorganised the empire, made Constantinople the new capital and legalised Christianity. Under Theodosius I ( r . 379–395), Christianity became the state religion and other religious practices were proscribed. In the reign of Heraclius ( r . 610–641), the Empire's military and administration were restructured and adopted Greek for official use in place of Latin.Although the Roman state continued and its traditions were maintained, modern historians distinguish Byzantium from ancient Rome insofar as it was centred on Constantinople, orientated towards Greek rather than Latin culture and characterised by Eastern Orthodox Christianity. The borders of the empire varied through 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, which it held for two more centuries. The Byzantine–Sasanian War of 602–628 exhausted the empire's resources and during the Early Muslim conquests of the 7th century, lost its richest provinces, Egypt and Syria, to the Arab caliphate. During the Macedonian dynasty (10th–11th centuries), the empire expanded again and experienced the two-century long Macedonian 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.The empire recovered during the Komnenian restoration and by the 12th century Constantinople was the largest and wealthiest European city .The Byzantine Empire was delivered a mortal blow during the Fourth Crusade, when Constantinople was sacked in 1204 and the territories that the empire formerly governed were divided into competing Byzantine Greek and Latin realms. Despite the eventual recovery of Constantinople in 1261, the Byzantine Empire 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 in the Byzantine–Ottoman wars over the 14th and 15th centuries. The Fall of Constantinople to the Ottoman Empire in 1453 ended the Byzantine Empire .The last of the imperial Byzantine successor states, the Empire of Trebizond, would be conquered by the Ottomans eight years later in the 1461 Siege of Trebizond.

Early History
The Roman army succeeded in conquering many territories covering the Mediterranean region and coastal regions in southwestern Europe and north Africa. These territories were home to many different cultural groups, both urban populations and rural populations. Generally speaking, the eastern Mediterranean provinces were more urbanised than the western, having previously been united under the Macedonian Empire and Hellenised by the influence of Greek culture .The West also suffered more heavily from the instability of the 3rd century AD. This distinction between the established Hellenised East and the younger Latinised West persisted and became increasingly important in later centuries, leading to a gradual estrangement of the two worlds .An early instance of the partition of the Empire into East and West occurred in 293, when Emperor Diocletian created a new administrative system (the tetrarchy), to guarantee security in all endangered regions of his Empire. He associated himself with a co-emperor (Augustus), and each co-emperor then adopted a young colleague given the title of Caesar, to share in their rule and eventually to succeed the senior partner. Each tetrarch was in charge of a part of the Empire. The tetrarchy collapsed, however, in 313 and a few years later Constantine I reunited the two administrative divisions of the Empire as sole Augustus.

Christianization and partition of the Empire
In 330, Constantine moved the seat of the Empire to Constantinople, which he founded as a second Rome on the site of Byzantium, a city strategically located on the trade routes between Europe and Asia and between the Mediterranean and the Black Sea. Constantine introduced important changes to the Empire's military, monetary, civil and religious institutions. In regards to his economic policies he has been accused by certain scholars of "reckless fiscality", but the gold solidus he introduced became a stable currency that transformed the economy and promoted development .Under Constantine, Christianity did not become the exclusive religion of the state, but enjoyed imperial preference since he supported it with generous privileges. Constantine established the principle that emperors could not settle questions of doctrine on their own, but should summon instead general ecclesiastical councils for that purpose. His convening of both the Synod of Arles and the First Council of Nicaea indicated his interest in the unity of the Church, and showcased his claim to be its head .The rise of Christianity was briefly interrupted on the accession of the emperor Julian in 361, who made a determined effort to restore polytheism throughout the empire and was thus dubbed "Julian the Apostate" by the Church.However, this was reversed when Julian was killed in battle in 363.Theodosius I (379–395) was the last Emperor to rule both the Eastern and Western halves of the Empire. In 391 and 392 he issued a series of edicts essentially banning pagan religion. Pagan festivals and sacrifices were banned, as was access to all pagan temples and places of worship .The last Olympic Games are believed to have been held in 393.In 395, Theodosius I bequeathed the imperial office jointly to his sons: Arcadius in the East and Honorius in the West, once again dividing Imperial administration. In the 5th century the Eastern part of the empire was largely spared the difficulties faced by the West – due in part to a more established urban culture and greater financial resources, which allowed it to placate invaders with tribute and pay foreign mercenaries. This success allowed Theodosius II to focus on the codification of Roman law and further fortification of the walls of Constantinople, which left the city impervious to most attacks until 1204 .Large portions of the Theodosian Walls are preserved to the present day.To fend off the Huns, Theodosius had to pay an enormous annual tribute to Attila. His successor, Marcian, refused to continue to pay the tribute, but Attila had already diverted his attention to the Western Roman Empire. After Attila's death in 453, the Hun Empire collapsed, and many of the remaining Huns were often hired as mercenaries by Constantinople.

Loss of the Western Roman Empire
After the fall of Attila, the Eastern Empire enjoyed a period of peace, while the Western Empire continued to deteriorate due to the expanding migration and invasions of the "barbarians", most prominently the Germanic nations. The West's end is usually dated 476 when the East Germanic Roman foederati general Odoacer deposed the Western Emperor Romulus Augustulus, a year after the latter usurped the position from Julius Nepos.In 480 with the death of the Julius Nepos, Eastern Emperor Zeno became sole claimant to Emperor of the empire. Odoacer, now ruler of Italy, was nominally Zeno's subordinate but acted with complete autonomy, eventually providing support to a rebellion against the Emperor .Zeno negotiated with the invading Ostrogoths, who had settled in Moesia, convincing the Gothic king Theodoric to depart for Italy as magister militum per Italiam ("commander in chief for Italy") with the aim of deposing Odoacer. By urging Theodoric to conquer Italy, Zeno rid the Eastern Empire of an unruly subordinate (Odoacer) and moved another (Theodoric) further from the heart of the Empire. After Odoacer's defeat in 493, Theodoric ruled Italy de facto, although he was never recognised by the eastern emperors as "king" (rex). In 491, Anastasius I, an aged civil officer of Roman origin, became Emperor, but it was not until 497 that the forces of the new emperor effectively took the measure of Isaurian resistance. Anastasius revealed himself as an energetic reformer and an able administrator. He introduced a new coinage system of the copper follis, the coin used in most everyday transactions .He also reformed the tax system and permanently abolished the chrysargyron tax. The State Treasury contained the enormous sum of 320,000 lb (150,000 kg) of gold when Anastasius died in 518.

Justinian dynasty
The Justinian dynasty was founded by Justin I, who though illiterate, rose through the ranks of the military to become Emperor in 518 .He was succeeded by his nephew Justinian I in 527, who may already have exerted effective control during Justin's reign. One of the most important figures of late antiquity and possibly the last Roman emperor to speak Latin as a first language, Justinian's rule constitutes a distinct epoch, marked by the ambitious but only partly realised renovatio imperii, or "restoration of the Empire". His wife Theodora was particularly influential.The Corpus forms the basis of civil law of many modern states.In 532, attempting to secure his eastern frontier, Justinian signed a peace treaty with Khosrau I of Persia, agreeing to pay a large annual tribute to the Sassanids. In the same year, he survived a revolt in Constantinople (the Nika riots), which solidified his power but ended with the deaths of a reported 30,000 to 35,000 rioters on his orders.The western conquests began in 533, as Justinian sent his general Belisarius to reclaim the former province of Africa from the Vandals, who had been in control since 429 with their capital at Carthage.Their success came with surprising ease, but it was not until 548 that the major local tribes were subdued.In 535, a small Byzantine expedition to Sicily met with easy success, but the Goths soon stiffened their resistance, and victory did not come until 540, when Belisarius captured Ravenna, after successful sieges of Naples and Rome.In 535–536, Theodahad sent Pope Agapetus I to Constantinople to request the removal of Byzantine forces from Sicily, Dalmatia, and Italy. Although Agapetus failed in his mission to sign a peace with Justinian, he succeeded in having the Monophysite Patriarch Anthimus I of Constantinople denounced, despite empress Theodora's support and protection.The Ostrogoths captured Rome in 546. Belisarius, who had been sent back to Italy in 544, was eventually recalled to Constantinople in 549 .The arrival of the Armenian eunuch Narses in Italy (late 551) with an army of 35,000 men marked another shift in Gothic fortunes. Totila was defeated at the Battle of Taginae and his successor, Teia, was defeated at the Battle of Mons Lactarius (October 552). Despite continuing resistance from a few Gothic garrisons and two subsequent invasions by the Franks and Alemanni, the war for the Italian peninsula was at an end .In 551, Athanagild, a noble from Visigothic Hispania, sought Justinian's help in a rebellion against the king, and the emperor dispatched a force under Liberius, a successful military commander. The empire held on to a small slice of the Iberian Peninsula coast until the reign of Heraclius. In the east, the Roman–Persian Wars continued until 561 when the envoys of Justinian and Khosrau agreed on a 50-year peace. By the mid-550s, Justinian had won victories in most theatres of operation, with the notable exception of the Balkans, which were subjected to repeated incursions from the Slavs and the Gepids. Tribes of Serbs and Croats were later resettled in the northwestern Balkans, during the reign of Heraclius .Justinian called Belisarius out of retirement and defeated the new Hunnish threat. The strengthening of the Danube fleet caused the Kutrigur Huns to withdraw and they agreed to a treaty that allowed safe passage back across the Danube. Although polytheism had been suppressed by the state since at least the time of Constantine in the 4th century, traditional Greco-Roman culture was still influential in the Eastern empire in the 6th century .Hellenistic philosophy began to be gradually amalgamated into newer Christian philosophy. Philosophers such as John Philoponus drew on neoplatonic ideas in addition to Christian thought and empiricism. Because of active paganism of its professors Justinian closed down the Neoplatonic Academy in 529. Other schools continued in Constantinople, Antioch and Alexandria which were the centers of Justinian's empire .Hymns written by Romanos the Melodist marked the development of the Divine Liturgy, while the architects Isidore of Miletus and Anthemius of Tralles worked to complete the new Church of the Holy Wisdom, Hagia Sophia, which was designed to replace an older church destroyed during the Nika Revolt. Completed in 537, the Hagia Sophia stands today as one of the major monuments of Byzantine architectural history .Maurice, who meanwhile succeeded Tiberius, intervened in a Persian civil war, placed the legitimate Khosrau II back on the throne, and married his daughter to him. Maurice's treaty with his new brother-in-law enlarged the territories of the Empire to the East and allowed the energetic Emperor to focus on the Balkans. By 602, a series of successful Byzantine campaigns had pushed the Avars and Slavs back across the Danube.However, Maurice's refusal to ransom several thousand captives taken by the Avars, and his order to the troops to winter in the Danube, caused his popularity to plummet. A revolt broke out under an officer named Phocas, who marched the troops back to Constantinople; Maurice and his family were murdered while trying to escape.

Early Heraclian dynasty
After Maurice's murder by Phocas, Khosrau used the pretext to reconquer the Roman province of Mesopotamia .Phocas, an unpopular ruler invariably described in Byzantine sources as a "tyrant", was the target of a number of Senate-led plots. He was eventually deposed in 610 by Heraclius, who sailed to Constantinople from Carthage with an icon affixed to the prow of his ship .Following the accession of Heraclius, the Sassanid advance pushed deep into the Levant, occupying Damascus and Jerusalem and removing the True Cross to Ctesiphon .The counter-attack launched by Heraclius took on the character of a holy war, and an acheiropoietos image of Christ was carried as a military standard (similarly, when Constantinople was saved from a combined Avar–Sassanid–Slavic siege in 626, the victory was attributed to the icons of the Virgin that were led in procession by Patriarch Sergius about the walls of the city).In this very siege of Constantinople of the year 626, amidst the climactic Byzantine–Sasanian War of 602–628, the combined Avar, Sassanid, and Slavic forces unsuccessfully besieged the Byzantine capital between June and July. After this, the Sassanid army was forced to withdraw to Anatolia. The loss came just after news had reached them of yet another Byzantine victory, where Heraclius's brother Theodore scored well against the Persian general Shahin. Following this, Heraclius led an invasion into Sassanid Mesopotamia once again.The main Sassanid force was destroyed at Nineveh in 627, and in 629 Heraclius restored the True Cross to Jerusalem in a majestic ceremony, as he marched into the Sassanid capital of Ctesiphon, where anarchy and civil war reigned as a result of the enduring war. Eventually, the Persians were obliged to withdraw all armed forces and return Sassanid-ruled Egypt, the Levant and whatever imperial territories of Mesopotamia and Armenia were in Roman hands at the time of an earlier peace treaty in c. 595. The war had exhausted both the Byzantines and Sassanids, however, and left them extremely vulnerable to the Muslim forces that emerged in the following years .The Byzantines suffered a crushing defeat by the Arabs at the Battle of Yarmouk in 636, while Ctesiphon fell in 637.

First Arab Siege of Constantinople (674–678) and the theme system
The Arabs, now firmly in control of Syria and the Levant, sent frequent raiding parties deep into Asia Minor, and in 674–678 laid siege to Constantinople itself. The Arab fleet was finally repulsed through the use of Greek fire, and a thirty-years' truce was signed between the Empire and the Umayyad Caliphate.However, the Anatolian raids continued unabated, and accelerated the demise of classical urban culture, with the inhabitants of many cities either refortifying much smaller areas within the old city walls, or relocating entirely to nearby fortresses.Constantinople itself dropped substantially in size, from 500,000 inhabitants to just 40,000–70,000, and, like other urban centres, it was partly ruralised. The city also lost the free grain shipments in 618, after Egypt fell first to the Persians and then to the Arabs, and public wheat distribution ceased.The void left by the disappearance of the old semi-autonomous civic institutions was filled by the system called theme, which entailed dividing Asia Minor into "provinces" occupied by distinct armies that assumed civil authority and answered directly to the imperial administration. This system may have had its roots in certain ad hoc measures taken by Heraclius, but over the course of the 7th century it developed into an entirely new system of imperial governance.The massive cultural and institutional restructuring of the Empire consequent on the loss of territory in the 7th century has been said to have caused a decisive break in east Mediterranean Romanness and that the Byzantine state is subsequently best understood as another successor state rather than a real continuation of the Roman Empire.

Twenty Years Anarchy
Justinian II (685–711) set in motion a chain of events by embarking on a despotic and increasingly violent course. His policies met with considerable opposition, eventually provoking a rebellion led by Leontios (695–698) in 695, which deposed and exiled him, precipitating a prolonged period of instability and anarchy, with seven emperors in twenty-two years.Leontios proved equally unpopular and was in turn overthrown by Tiberios III (698–705). Tiberios managed to bolster the eastern frontier and reinforced the defenses of Constantinople, but meanwhile Justinian was conspiring to make a comeback and after forming an alliance with the Bulgars succeeded in taking Constantinople and executing Tiberios. Justinian then continued to reign for a further six years (705–711). His treatment of Tiberios and his supporters had been brutal and he continued to rule in a manner that was despotic and cruel. He lost the ground regained by Tiberios in the east, and imposed his views on the Pope. However, before long he faced a rebellion led by Philippikos Bardanes (711–713). Justinian was captured and executed as was his son and co-emperor, Tiberius (706–711), thus extinguishing the Heraclian line. Justinian had taken the Byzantine empire yet further from its origins. He effectively abolished the historical role of Consul, merging it with Emperor, thus strengthening the Emperors' constitutional position as absolute monarch.Philippikos' rebellion extended beyond politics to religion, deposing the Patriarch Cyrus, reestablishing Monothelitism and overturning the Sixth Ecumenical Council, which in turn alienated the empire from Rome. Militarily the Bulgars reached the walls of Constantinople, and moving troops to defend the capital allowed the Arabs to make incursions in the east. His reign ended abruptly when an army rebellion deposed him and replaced him with Anastasius II (713–715).Anastasius reversed his predecessor's religious policies and responded to Arab attacks by sea and land, this time reaching as far as Galatia in 714, with some success. However the very army that had placed him on the throne (the Opsikion army) rose against him, proclaimed a new emperor and besieged Constantinople for six months, eventually forcing Anastasius to flee.The troops had proclaimed Theodosius III (715–717) as the new emperor, and once he had overcome Anastasius was almost immediately faced with the Arab preparations for the Second Arab siege of Constantinople (717–718), forcing him to seek assistance from the Bulgars. He in turn faced rebellion from two other themata, Anatolikon and Armeniakon in 717, and chose to resign, being succeeded by Leo III (717–741) bringing an end to the cycle of violence and instability. It is surprising that the Byzantine Empire was able to survive, given its internal problems, the speed with which the Sassanid Empire collapsed under the Arab threat, and the fact that it was being threatened simultaneously on two fronts. However the strength of the military organization within the empire, and factional struggles within the Arab world enabled it to do so.

Second Arab Siege of Constantinople (717–718) and the Isaurian dynasty
In 717 the Umayyad Caliphate launched the Siege of Constantinople (717–718) which lasted for one year. However, the combination of Leo III the Isaurian's military genius, the Byzantines' use of Greek Fire, a cold winter in 717–718, and Byzantine diplomacy with the Khan Tervel of Bulgaria resulted in a Byzantine victory. After Leo III turned back the Muslim assault in 718, he addressed himself to the task of reorganising and consolidating the themes in Asia Minor. In 740 a major Byzantine victory took place at the Battle of Akroinon where the Byzantines destroyed the Umayyad army once again.Leo III the Isaurian's son and successor, Constantine V, won noteworthy victories in northern Syria and also thoroughly undermined Bulgarian strength .In 746, profiting by the unstable conditions in the Umayyad Caliphate, which was falling apart under Marwan II, Constantine V invaded Syria and captured Germanikeia and the Battle of Keramaia resulted in a major Byzantine naval victory over the Umayyad fleet. Coupled with military defeats on other fronts of the Caliphate and internal instability, Umayyad expansion came to an end.

Religious dispute over iconoclasm
The 8th and early 9th centuries were also dominated by controversy and religious division over Iconoclasm, which was the main political issue in the Empire for over a century. Icons (here meaning all forms of religious imagery) were banned by Leo and Constantine from around 730, leading to revolts by iconodules (supporters of icons) throughout the empire. After the efforts of empress Irene, the Second Council of Nicaea met in 787 and affirmed that icons could be venerated but not worshiped. Irene is said to have endeavoured to negotiate a marriage between herself and Charlemagne, but, according to Theophanes the Confessor, the scheme was frustrated by Aetios, one of her favourites .In the early 9th century, Leo V reintroduced the policy of iconoclasm, but in 843 empress Theodora restored the veneration of icons with the help of Patriarch Methodios .Iconoclasm played a part in the further alienation of East from West, which worsened during the so-called Photian schism, when Pope Nicholas I challenged the elevation of Photios to the patriarchate.

Macedonian dynasty and resurgence (867–1025)
The accession of Basil I to the throne in 867 marks the beginning of the Macedonian dynasty, which would rule for the next two and a half centuries. This dynasty included some of the most able emperors in Byzantium's history, and the period is one of revival and resurgence. The Empire moved from defending against external enemies to reconquest of territories formerly lost .In addition to a reassertion of Byzantine military power and political authority, the period under the Macedonian dynasty is characterised by a cultural revival in spheres such as philosophy and the arts. There was a conscious effort to restore the brilliance of the period before the Slavic and subsequent Arab invasions, and the Macedonian era has been dubbed the "Golden Age" of Byzantium .Although the Empire was significantly smaller than during the reign of Justinian, it had regained significant strength, as the remaining territories were less geographically dispersed and more politically, economically, and culturally integrated.

Wars against the Abbasids
Taking advantage of the Empire's weakness after the Revolt of Thomas the Slav in the early 820s, the Arabs re-emerged and captured Crete. They also successfully attacked Sicily, but in 863 general Petronas gained a decisive victory against Umar al-Aqta, the emir of Melitene (Malatya). Under the leadership of emperor Krum, the Bulgarian threat also re-emerged, but in 815–816 Krum's son, Omurtag, signed a peace treaty with Leo V .In the 830s Abbasid Caliphate started military excursions culminating with a victory in the Sack of Amorium. The Byzantines then attacked back and sacked Damietta in Egypt. Later the Abbasid Caliphate responded by sending their troops into Anatolia again, sacking and marauding until they were eventually annihilated by the Byzantines in 863.In the early years of Basil I's reign, Arab raids on the coasts of Dalmatia were successfully repelled, and the region once again came under secure Byzantine control. This enabled Byzantine missionaries to penetrate to the interior and convert the Serbs and the principalities of modern-day Herzegovina and Montenegro to Orthodox Christianity. By contrast, the Byzantine position in Southern Italy was gradually consolidated so that by 873 Bari was once again under Byzantine rule, and most of Southern Italy would remain in the Empire for the next 200 years.On the more important eastern front, the Empire rebuilt its defences and went on the offensive. The Paulicians were defeated and their capital of Tephrike (Divrigi) taken, while the offensive against the Abbasid Caliphate began with the recapture of Samosata.Under Basil's son and successor, Leo VI the Wise, the gains in the east against the now-weak Abbasid Caliphate continued. However, Sicily was lost to the Arabs in 902, and in 904 Thessaloniki, the Empire's second city, was sacked by an Arab fleet. The naval weakness of the Empire was rectified. Despite this revenge the Byzantines were still unable to strike a decisive blow against the Muslims, who inflicted a crushing defeat on the imperial forces when they attempted to regain Crete in 911 .Melitene was permanently recaptured in 934, and in 943 the famous general John Kourkouas continued the offensive in Mesopotamia with some noteworthy victories, culminating in the reconquest of Edessa. Kourkouas was especially celebrated for returning to Constantinople the venerated Mandylion, a relic purportedly imprinted with a portrait of Christ.The soldier-emperors Nikephoros II Phokas ( r . 963–969) and John I Tzimiskes (969–976) expanded the empire well into Syria, defeating the emirs of north-west Iraq. The great city of Aleppo was taken by Nikephoros in 962 and the Arabs were decisively expelled from Crete in 963. The recapture of Crete put an end to Arab raids in the Aegean allowing mainland Greece to flourish once again. Cyprus was permanently retaken in 965 and the successes of Nikephoros culminated in 969 with the recapture of Antioch, which he incorporated as a province of the Empire.His successor John Tzimiskes recaptured Damascus, Beirut, Acre, Sidon, Caesarea, and Tiberias, putting Byzantine armies within striking distance of Jerusalem, although the Muslim power centres in Iraq and Egypt were left untouched.After much campaigning in the north, the last Arab threat to Byzantium, the rich province of Sicily, was targeted in 1025 by Basil II, who died before the expedition could be completed. Nevertheless, by that time the Empire stretched from the straits of Messina to the Euphrates and from the Danube to Syria.

Wars against the Bulgarian Empire
The traditional struggle with the See of Rome continued through the Macedonian period, spurred by the question of religious supremacy over the newly Christianised state of Bulgaria .Ending eighty years of peace between the two states, the powerful Bulgarian tsar Simeon I invaded in 894 but was pushed back by the Byzantines, who used their fleet to sail up the Black Sea to attack the Bulgarian rear, enlisting the support of the Hungarians .The Byzantines were defeated at the Battle of Boulgarophygon in 896, however, and agreed to pay annual subsidies to the Bulgarians .The Byzantines were defeated at the Battle of Boulgarophygon in 896, however, and agreed to pay annual subsidies to the Bulgarians .Leo the Wise died in 912, and hostilities soon resumed as Simeon marched to Constantinople at the head of a large army. Although the walls of the city were impregnable, the Byzantine administration was in disarray and Simeon was invited into the city, where he was granted the crown of basileus (emperor) of Bulgaria and had the young emperor Constantine VII marry one of his daughters. When a revolt in Constantinople halted his dynastic project, he again invaded Thrace and conquered Adrianople as well as having to fight on two fronts. A great imperial expedition under Leo Phocas and Romanos I Lekapenos ended with another crushing Byzantine defeat at the Battle of Achelous in 917, and the following year the Bulgarians were free to ravage northern Greece. Adrianople was plundered again in 923, and a Bulgarian army laid siege to Constantinople in 924. Simeon died suddenly in 927, however, and Bulgarian power collapsed with him. Bulgaria and Byzantium entered a long period of peaceful relations, and the Empire was now free to concentrate on the eastern front against the Muslims .In 968, Bulgaria was overrun by the Rus' under Sviatoslav I of Kiev, but three years later, John I Tzimiskes defeated the Rus' and re-incorporated Eastern Bulgaria into the Byzantine Empire.Bulgarian resistance revived under the rule of the Cometopuli dynasty, but the new Emperor Basil II ( r . 976–1025) made the submission of the Bulgarians his primary goal.Basil's first expedition against Bulgaria, however, resulted in a defeat at the Gates of Trajan. For the next few years, the emperor would be preoccupied with internal revolts in Anatolia, while the Bulgarians expanded their realm in the Balkans. The war dragged on for nearly twenty years. The Byzantine victories of Spercheios and Skopje decisively weakened the Bulgarian army, and in annual campaigns, Basil methodically reduced the Bulgarian strongholds.At the Battle of Kleidion in 1014 the Bulgarians were annihilated: their army was captured, and it is said that 99 out of every 100 men were blinded, with the hundredth man left with one eye so he could lead his compatriots home. When Tsar Samuil saw the broken remains of his once formidable army, he died of shock. By 1018, the last Bulgarian strongholds had surrendered, and the country became part of the Empire.This victory restored the Danube frontier, which had not been held since the days of the Emperor Heraclius.

Relations with the Kievan Rus'
Between 850 and 1100, the Empire developed a mixed relationship with the new state of the Kievan Rus', which had emerged to the north across the Black Sea.This relationship would have long-lasting repercussions in the history of the East Slavs, and the Empire quickly became the main trading and cultural partner for Kiev. The Rus' launched their first attack against Constantinople in 860, pillaging the suburbs of the city. In 941, they appeared on the Asian shore of the Bosphorus, but this time they were crushed, an indication of the improvements in the Byzantine military position after 907, when only diplomacy had been able to push back the invaders. Basil II could not ignore the emerging power of the Rus', and, following the example of his predecessors, he used religion as a means for the achievement of political purposes .Rus'–Byzantine relations became closer following the marriage of Anna Porphyrogeneta to Vladimir the Great in 988, and the subsequent Christianisation of the Rus'. Byzantine priests, architects, and artists were invited to work on numerous cathedrals and churches around Rus', expanding Byzantine cultural influence even further, while numerous Rus' served in the Byzantine army as mercenaries, most notably as the famous Varangian Guard .Even after the Christianisation of the Rus', however, relations were not always friendly. The most serious conflict between the two powers was the war of 968–971 in Bulgaria, but several Rus' raiding expeditions against the Byzantine cities of the Black Sea coast and Constantinople itself are also recorded. Although most were repulsed, they were often followed by treaties that were generally favourable to the Rus', such as the one concluded at the end of the war of 1043, during which the Rus' gave an indication of their ambitions to compete with the Byzantines as an independent power.

Campaigns in the Caucasus
Between 1021 and 1022, following years of tensions, Basil II led a series of victorious campaigns against the Kingdom of Georgia, resulting in the annexation of several Georgian provinces to the Empire. Basil's successors also annexed Bagratid Armenia in 1045. Importantly, both Georgia and Armenia were significantly weakened by the Byzantine administration's policy of heavy taxation and abolishing of the levy. The weakening of Georgia and Armenia would play a significant role in the Byzantine defeat at Manzikert in 1071.

Apex
Basil II is considered among the most capable Byzantine emperors and his reign as the apex of the empire in the Middle Ages. By 1025, the date of Basil II's death, the Byzantine Empire stretched from Armenia in the east to Calabria in Southern Italy in the west. Many successes had been achieved, ranging from the conquest of Bulgaria to the annexation of parts of Georgia and Armenia, and the reconquest of Crete, Cyprus, and the important city of Antioch. These were not temporary tactical gains but long-term reconquests .Leo VI achieved the complete codification of Byzantine law in Greek. This monumental work of 60 volumes became the foundation of all subsequent Byzantine law and is still studied today.Leo also reformed the administration of the Empire, redrawing the borders of the administrative subdivisions (the Themata, or "Themes") and tidying up the system of ranks and privileges, as well as regulating the behaviour of the various trade guilds in Constantinople. Leo's reform did much to reduce the previous fragmentation of the Empire, which henceforth had one center of power, Constantinople.However, the increasing military success of the Empire greatly enriched and empowered the provincial nobility with respect to the peasantry, who were essentially reduced to a state of serfdom.

Split between Orthodoxy and Catholicism (1054)
The Macedonian period also included events of momentous religious significance. The conversion of the Bulgarians, Serbs and Rus' to Orthodox Christianity drew the religious map of Europe which still resonates today. Cyril and Methodius, two Byzantine Greek brothers from Thessaloniki, contributed significantly to the Christianization of the Slavs and in the process devised the Glagolitic alphabet, ancestor to the Cyrillic script.In 1054, relations between the Eastern and Western traditions of the Chalcedonian Christian Church reached a terminal crisis, known as the East–West Schism. Although there was a formal declaration of institutional separation, on 16 July, when three papal legates entered the Hagia Sophia during Divine Liturgy on a Saturday afternoon and placed a bull of excommunication on the altar, the so-called Great Schism was actually the culmination of centuries of gradual separation.

Crisis and fragmentation
The Byzantine Empire soon fell into a period of difficulties, caused to a large extent by the undermining of the theme system and the neglect of the military. Nikephoros II, John Tzimiskes, and Basil II shifted the emphasis of the military divisions (τάγματα, tagmata) from a reactive, defence-oriented citizen army into an army of professional career soldiers, increasingly dependent on foreign mercenaries. Mercenaries were expensive, however, and as the threat of invasion receded in the 10th century, so did the need for maintaining large garrisons and expensive fortifications.Basil II left a burgeoning treasury upon his death, but he neglected to plan for his succession. None of his immediate successors had any particular military or political talent and the imperial administration increasingly fell into the hands of the civil service. Incompetent efforts to revive the Byzantine economy resulted in severe inflation and a debased gold currency. The army was now seen as both an unnecessary expense and a political threat. A number of standing local units were demobilised, further augmenting the army's dependence on mercenaries, who could be retained and dismissed on an as-needed basis .At the same time, Byzantium was faced with new enemies. Its provinces in southern Italy were threatened by the Normans, who arrived in Italy at the beginning of the 11th century. During a period of strife between Constantinople and Rome culminating in the East-West Schism of 1054, the Normans began to advance, slowly but steadily, into Byzantine Italy .Reggio, the capital of the tagma of Calabria, was captured in 1060 by Robert Guiscard, followed by Otranto in 1068. Bari, the main Byzantine stronghold in Apulia, was besieged in August 1068 and fell in April 1071 .In 1048-9, the Seljuk Turks under Ibrahim Yinal made their first incursion into the Byzantine frontier region of Iberia and defeated a combined Byzantine-Georgian army of 50,000 at the Battle of Kapetrou on 10 September 1048. The Arab chronicler Ibn al-Athir reports that Ibrahim brought back 100,000 captives and a vast booty loaded on the backs of ten thousand camels. About 1053 Constantine IX disbanded what the historian John Skylitzes calls the "Iberian Army", which consisted of 50,000 men and it was turned into a contemporary Drungary of the Watch. Two other knowledgeable contemporaries, the former officials Michael Attaleiates and Kekaumenos, agree with Skylitzes that by demobilising these soldiers Constantine did catastrophic harm to the Empire's eastern defences.The emergency lent weight to the military aristocracy in Anatolia, who in 1068 secured the election of one of their own, Romanos Diogenes, as emperor. In the summer of 1071, Romanos undertook a massive eastern campaign to draw the Seljuks into a general engagement with the Byzantine army. At the Battle of Manzikert, Romanos suffered a surprise defeat by Sultan Alp Arslan, and he was captured. Alp Arslan treated him with respect and imposed no harsh terms on the Byzantines .In Constantinople, however, a coup put in power Michael Doukas, who soon faced the opposition of Nikephoros Bryennios and Nikephoros Botaneiates. By 1081, the Seljuks had expanded their rule over virtually the entire Anatolian plateau from Armenia in the east to Bithynia in the west, and they had founded their capital at Nicaea, just 90 kilometres (56 miles) from Constantinople.

Komnenian dynasty and the Crusades
During the Komnenian, or Comnenian, period from about 1081 to about 1185, the five emperors of the Komnenos dynasty (Alexios I, John II, Manuel I, Alexios II, and Andronikos I) presided over a sustained, though ultimately incomplete, restoration of the military, territorial, economic, and political position of the Byzantine Empire. Although the Seljuk Turks occupied the heartland of the Empire in Anatolia, most Byzantine military efforts during this period were directed against Western powers, particularly the Normans.The Empire under the Komnenoi played a key role in the history of the Crusades in the Holy Land, which Alexios I had helped bring about, while also exerting enormous cultural and political influence in Europe, the Near East, and the lands around the Mediterranean Sea under John and Manuel. Contact between Byzantium and the "Latin" West, including the Crusader states, increased significantly during the Komnenian period. Venetian and other Italian traders became resident in large numbers in Constantinople and the empire (there were an estimated 60,000 Latins in Constantinople alone, out of a population of three to four hundred thousand), and their presence together with the numerous Latin mercenaries who were employed by Manuel helped to spread Byzantine technology, art, literature and culture throughout the Latin West, while also leading to a flow of Western ideas and customs into the Empire.In terms of prosperity and cultural life, the Komnenian period was one of the peaks in Byzantine history, and Constantinople remained the leading city of the Christian world in size, wealth, and culture. There was a renewed interest in classical Greek philosophy, as well as an increase in literary output in vernacular Greek.Byzantine art and literature held a pre-eminent place in Europe, and the cultural impact of Byzantine art on the west during this period was enormous and of long lasting significance.

Alexios I and the First Crusade
After Manzikert, a partial recovery (referred to as the Komnenian restoration) was made possible by the Komnenian dynasty. The Komnenoi attained power again under Alexios I in 1081. From the outset of his reign, Alexios faced a formidable attack by the Normans under Robert Guiscard and his son Bohemund of Taranto, who captured Dyrrhachium and Corfu, and laid siege to Larissa in Thessaly. Robert Guiscard's death in 1085 temporarily eased the Norman problem. The following year, the Seljuq sultan died, and the sultanate was split by internal rivalries. By his own efforts, Alexios defeated the Pechenegs; they were caught by surprise and annihilated at the Battle of Levounion on 28 April 1091.Having achieved stability in the West, Alexios could turn his attention to the severe economic difficulties and the disintegration of the Empire's traditional defences.However, he still did not have enough manpower to recover the lost territories in Asia Minor and to advance against the Seljuks. At the Council of Piacenza in 1095, envoys from Alexios spoke to Pope Urban II about the suffering of the Christians of the East, and underscored that without help from the West they would continue to suffer under Muslim rule.Urban saw Alexios's request as a dual opportunity to cement Western Europe and reunite the Eastern Orthodox Church with the Roman Catholic Church under his rule. On 27 November 1095, Pope Urban II called together the Council of Clermont, and urged all those present to take up arms under the sign of the Cross and launch an armed pilgrimage to recover Jerusalem and the East from the Muslims. The response in Western Europe was overwhelming. Alexios had anticipated help in the form of mercenary forces from the West, but he was totally unprepared for the immense and undisciplined force that soon arrived in Byzantine territory. It was no comfort to Alexios to learn that four of the eight leaders of the main body of the Crusade were Normans, among them Bohemund. Since the crusade had to pass through Constantinople, however, the Emperor had some control over it. He required its leaders to swear to restore to the empire any towns or territories they might reconquer from the Turks on their way to the Holy Land. In return, he gave them guides and a military escort. Alexios was able to recover a number of important cities and islands, and in fact much of western Asia Minor. The Crusaders agreed to become Alexios' vassals under the Treaty of Devol in 1108, which marked the end of the Norman threat during Alexios' reign.

John II, Manuel I and the Second Crusade
Alexios's son John II Komnenos succeeded him in 1118 and ruled until 1143. John was a pious and dedicated Emperor who was determined to undo the damage to the empire suffered at the Battle of Manzikert, half a century earlier. Famed for his piety and his remarkably mild and just reign, John was an exceptional example of a moral ruler at a time when cruelty was the norm. For this reason, he has been called the Byzantine Marcus Aurelius.During his twenty-five-year reign, John made alliances with the Holy Roman Empire in the West and decisively defeated the Pechenegs at the Battle of Beroia.He thwarted Hungarian and Serbian threats during the 1120s, and in 1130 he allied himself with the German emperor Lothair III against the Norman king Roger II of Sicily .In the later part of his reign, John focused his activities on the East, personally leading numerous campaigns against the Turks in Asia Minor. His campaigns fundamentally altered the balance of power in the East, forcing the Turks onto the defensive, while restoring many towns, fortresses, and cities across the peninsula to the Byzantines. He defeated the Danishmend Emirate of Melitene and reconquered all of Cilicia, while forcing Raymond of Poitiers, Prince of Antioch, to recognise Byzantine suzerainty. In an effort to demonstrate the Emperor's role as the leader of the Christian world, John marched into the Holy Land at the head of the combined forces of the Empire and the Crusader states; yet despite his great vigour pressing the campaign, his hopes were disappointed by the treachery of his Crusader allies.In 1142, John returned to press his claims to Antioch, but he died in the spring of 1143 following a hunting accident.John's chosen heir was his fourth son, Manuel I Komnenos, who campaigned aggressively against his neighbours both in the west and in the east. In Palestine, Manuel allied with the Crusader Kingdom of Jerusalem and sent a large fleet to participate in a combined invasion of Fatimid Egypt. Manuel reinforced his position as overlord of the Crusader states, with his hegemony over Antioch and Jerusalem secured by agreement with Raynald, Prince of Antioch, and Amalric, King of Jerusalem. In an effort to restore Byzantine control over the ports of southern Italy, he sent an expedition to Italy in 1155, but disputes within the coalition led to the eventual failure of the campaign. Despite this military setback, Manuel's armies successfully invaded the Southern parts of the Kingdom of Hungary in 1167, defeating the Hungarians at the Battle of Sirmium. By 1168, nearly the whole of the eastern Adriatic coast lay in Manuel's hands.Manuel made several alliances with the Pope and Western Christian kingdoms, and he successfully handled the passage of the Second Crusade through his empire.In the east, however, Manuel suffered a major defeat in 1176 at the Battle of Myriokephalon, against the Turks. Yet the losses were quickly recovered, and in the following year Manuel's forces inflicted a defeat upon a force of "picked Turks". The Byzantine commander John Vatatzes, who destroyed the Turkish invaders at the Battle of Hyelion and Leimocheir, not only brought troops from the capital but also was able to gather an army along the way, a sign that the Byzantine army remained strong and that the defensive program of western Asia Minor was still successful.

12th-century Renaissance
John and Manuel pursued active military policies, and both deployed considerable resources on sieges and on city defences; aggressive fortification policies were at the heart of their imperial military policies. Despite the defeat at Myriokephalon, the policies of Alexios, John and Manuel resulted in vast territorial gains, increased frontier stability in Asia Minor, and secured the stabilisation of the Empire's European frontiers. From c. 1081 to c. 1180, the Komnenian army assured the Empire's security, enabling Byzantine civilisation to flourish.

Angelid dynasty
Manuel's death on 24 September 1180 left his 11-year-old son Alexios II Komnenos on the throne. Alexios was highly incompetent in the office, and with his mother Maria of Antioch's Frankish background, made his regency unpopular Eventually, Andronikos I Komnenos, a grandson of Alexios I, launched a revolt against his younger relative and managed to overthrow him in a violent coup d'état. Utilizing his good looks and his immense popularity with the army, he marched on to Constantinople in August 1182 and incited a massacre of the Latins .After eliminating his potential rivals, he had himself crowned as co-emperor in September 1183. He eliminated Alexios II, and took his 12-year-old wife Agnes of France for himself .Andronikos began his reign well; in particular, the measures he took to reform the government of the Empire have been praised by historians. According to George Ostrogorsky, Andronikos was determined to root out corruption: Under his rule, the sale of offices ceased; selection was based on merit, rather than favouritism; officials were paid an adequate salary so as to reduce the temptation of bribery. In the provinces, Andronikos's reforms produced a speedy and marked improvement .The aristocrats were infuriated against him, and to make matters worse, Andronikos seems to have become increasingly unbalanced; executions and violence became increasingly common, and his reign turned into a reign of terror.Andronikos seemed almost to seek the extermination of the aristocracy as a whole. The struggle against the aristocracy turned into wholesale slaughter, while the Emperor resorted to ever more ruthless measures to shore up his regime.Despite his military background, Andronikos failed to deal with Isaac Komnenos, Béla III of Hungary ( r . 1172–1196) who reincorporated Croatian territories into Hungary, and Stephen Nemanja of Serbia ( r . 1166–1196) who declared his independence from the Byzantine Empire. Yet, none of these troubles would compare to William II of Sicily's ( r . 1166–1189) invasion force of 300 ships and 80,000 men, arriving in 1185.Andronikos mobilised a small fleet of 100 ships to defend the capital, but other than that he was indifferent to the populace. He was finally overthrown when Isaac Angelos, surviving an imperial assassination attempt, seized power with the aid of the people and had Andronikos killed.The reign of Isaac II, and more so that of his brother Alexios III, saw the collapse of what remained of the centralised machinery of Byzantine government and defence. Although the Normans were driven out of Greece, in 1186 the Vlachs and Bulgars began a rebellion that led to the formation of the Second Bulgarian Empire. The internal policy of the Angeloi was characterised by the squandering of the public treasure and fiscal maladministration. Imperial authority was severely weakened, and the growing power vacuum at the center of the Empire encouraged fragmentation. There is evidence that some Komnenian heirs had set up a semi-independent state in Trebizond before 1204.

Fourth Crusade
In 1198, Pope Innocent III broached the subject of a new crusade through legates and encyclical letters.[153] The stated intent of the crusade was to conquer Egypt, now the centre of Muslim power in the Levant. The crusader army that arrived at Venice in the summer of 1202 and hired the Venetian fleet to transport them to Egypt. As payment to the Venetians, they captured the (Christian) port of Zara in Dalmatia (vassal city of Venice, which had rebelled and placed itself under Hungary's protection in 1186).

Crusader sack of Constantinople (1204)
The crusaders arrived at Constantinople in the summer of 1203 and quickly attacked, starting a major fire that damaged large parts of the city, and briefly seized control. Alexios III fled from the capital and Alexios Angelos was elevated to the throne as Alexios IV along with his blind father Isaac. Alexios IV and Isaac II were unable to keep their promises and were deposed by Alexios V. The crusaders again took the city on 13 April 1204 and Constantinople was subjected to pillage and massacre by the rank and file for three days. Many priceless icons, relics and other objects later turned up in Western Europe, a large number in Venice. According to Choniates, a prostitute was even set up on the Patriarchal throne.When order had been restored, the crusaders and the Venetians proceeded to implement their agreement; Baldwin of Flanders was elected Emperor of a new Latin Empire and the Venetian Thomas Morosini was chosen as Patriarch. The lands divided up among the leaders included most of the former Byzantine possessions, though resistance would continue through the Byzantine remnants of Nicaea, Trebizond, and Epirus. Although Venice was more interested in commerce than conquering territory, it took key areas of Constantinople and the Doge took the title of "Lord of a Quarter and Half a Quarter of the Roman Empire".

Empire in exile
After the sack of Constantinople in 1204 by Latin crusaders, two Byzantine successor states were established: the Empire of Nicaea, and the Despotate of Epirus. A third, the Empire of Trebizond, was created after Alexios Komnenos, commanding the Georgian expedition in Chaldia a few weeks before the sack of Constantinople, found himself de facto emperor, and established himself in Trebizond. Of the three successor states, Epirus and Nicaea stood the best chance of reclaiming Constantinople. The Nicaean Empire struggled to survive the next few decades, however, and by the mid-13th century it had lost much of southern Anatolia.[160] The weakening of the Sultanate of Rûm following the Mongol invasion in 1242–43 allowed many beyliks and ghazis to set up their own principalities in Anatolia, weakening the Byzantine hold on Asia Minor. In time, one of the Beys, Osman I, created an empire that would eventually conquer Constantinople. However, the Mongol invasion also gave Nicaea a temporary respite from Seljuk attacks, allowing it to concentrate on the Latin Empire to its north.

Reconquest of Constantinople
The Empire of Nicaea, founded by the Laskarid dynasty, managed to effect the Recapture of Constantinople from the Latins in 1261 and defeat Epirus. This led to a short-lived revival of Byzantine fortunes under Michael VIII Palaiologos but the war-ravaged Empire was ill-equipped to deal with the enemies that surrounded it. To maintain his campaigns against the Latins, Michael pulled troops from Asia Minor and levied crippling taxes on the peasantry, causing much resentment.Massive construction projects were completed in Constantinople to repair the damage of the Fourth Crusade but none of these initiatives was of any comfort to the farmers in Asia Minor suffering raids from Muslim ghazis.Rather than holding on to his possessions in Asia Minor, Michael chose to expand the Empire, gaining only short-term success. To avoid another sacking of the capital by the Latins, he forced the Church to submit to Rome, again a temporary solution for which the peasantry hated Michael and Constantinople. The efforts of Andronikos II and later his grandson Andronikos III marked Byzantium's last genuine attempts in restoring the glory of the Empire. However, the use of mercenaries by Andronikos II would often backfire, with the Catalan Company ravaging the countryside and increasing resentment towards Constantinople.