How did the battle of Manzikert (1071) change the Byzantine Empire?
The Byzantine Empire was the successor to the Roman Empire and ruled a large area in Europe and the Middle East. Byzantine played a major role in the Balkans and Russia and it successfully kept the Arabs and the Muslims out of Europe for centuries. In 1071 the Empire seemed invincible, it had reversed many years of decline under a series of energetic Emperors. It had recovered territory that had been lost to its enemies and had morphed into a powerful political and military force.
The Battle of Manzikert fundamentally reversed this upward trend and led to the decline of the Byzantine Empire. As Byzantine collapsed, Turkish Muslims gradually gained control of Asia Minor. As Muslims took control of the Christian holy lands, European countries responded by launching the Crusades. The Battle of Manzikert is one of the most important in medieval history and its repercussions can still be felt today.
By 1050 the Byzantine Empire was a strong state, with a highly professional army, sophisticated bureaucracy and extensive territories from northern Iraq to the Danube. The Empire had enjoyed a renaissance under the Macedonian Dynasty and especially under the capable Basil II. A common Greek Christian Orthodox Culture unified the diverse peoples’ of the realm, and this was exported to the Slavs of Eastern Europe. However, after the death of Basil II, the Macedonian dynasty came to an end and the Empire was led by a series of ineffectual Emperors and was devastated by several civil wars.
In 1071, the Emperor was Romanus IV Diogenes (1068–1071), a member of the Cappadocian military aristocracy. He was an experienced general, but he had alienated many in the Byzantine aristocracy who saw him as a usurper and resented his authoritarianism. The strategic situation facing the Byzantine Empire was precarious. The Empire had appeared secure, especially after the destruction of the Bulgar Empire, but the Pencheng Turks, from the Eurasian Steppes threatened the Empire’s Balkan and Black Sea possessions. In Italy, the Normans were seizing the last remaining Byzantine possessions in Italy. The biggest threat to the Empire was posed by the Seljuk Turks.
The Seljuk Turks had been nomads in Central Asia and had been converted to Islam around 1000 AD. The Turks were led by the Seljuk family and they invaded southwestern Asia in the 11th century. They were able to defeat the various Muslim dynasties that had seized power after the decline of the Abbasid Caliphate. They founded an empire that included Mesopotamia, Syria, Palestine, and the majority of Iran. Their conquests were the start of Turkish domination in the Middle East that lasted for centuries. The Seljuks attacked the Christian allies of the Byzantines in the Caucasus' and conquered Armenia. They also began to raid deep into Byzantine territory which they regarded as a Jihad and even managed to seize key fortresses in the Christian Empire’s territory.
Battle of Manzikert
The Byzatine Empire was concerned by the Seljuk raids into Anatolia. Emperor Romanus needed its resources and the Anatolian provinces were the source of most of its military manpower. The Seljuk raids had led to the near collapse of the eastern frontier and many Turkish nomads had entered the area. The Emperor assembled a large army to reestablish the security of the Byzantine Empire’s regions.
In 1071, Romanus led his army into areas of Armenia that had been seized by the Turks, with the aim of regaining key defensive fortresses. Romanus’ army was mainly mounted heavy cavalry with some militia, it was also accompanied by large contingents of mercenaries. The tactics of Romanus was very unusual, as the Byzantine’s were usually reluctant to engage in offensive actions. Near the town of Manzikert, he divided his army, sending a large contingent to besiege a fortress.
The Seljuk army was under the command of Sultan Alp Arslan. The Turks had excellent intelligence and they were all mounted. When Alp Arslan heard that the Byzantines had divided his forces he rapidly advanced to Manzikert, where he confronted the emperor’s army. Arslan knew that he outnumbered Romanus' forces. The Byzantines were taken completely by surprise and Romanus abandoned Manzikert, to reunite his forces.
However, Alp Arslan attacked the Byzantines as they retreated, and his mounted archers inflicted heavy casualties on the Christians. Romanus had failed to scout the area and he had blundered into a trap. Romanus fought valiantly, and his men attacked the enemy with such ferocity that they seemed to be on the verge of victory. The Byzantines knights smashed into the lightly armored Turkish horsemen with great success. However, many of his mercenaries were Uz Turks and they defected to their kinsmen in the Seljuk army. One of the Romanus' key Byzantine generals retreated without warning. It is entirely clear if he Uz Turks defecting to the Seljuks or he simply hated Romanus. The sources disagree on why the Byzatine general left the battle. The general's defection led to the destruction of the Byzantine army. Romanus was taken prisoner and ritually humiliated.
After securing the submission of the Emperor, Alp Arslan treated Romanus well and later released him. During the Emperor's absence and the defeat at Manzikert, a usurper seiazed power. Romanus tried to regain his realm but was defeated in battle, blinded and killed in 1072.
Manzikert and the decline of the Byzantine Empire
The defeat at Manzikert in 1071 was a disaster for the Byzantines. In the aftermath of their victory over Romanus, the Turks swept into Anatolia unopposed. They only faced local resistance from Byzantine lords in the Anatolian provinces. The Byzantine eastern frontier effectively collapsed and Turkish nomads entered Anatolia at will. Alp Arslan turned his attention to Fatimid Egypt fortunately for the Byzantines. In the immediate aftermath of the defeat of Manzikert there was no real effective Byzantine Emperor. This was a disaster, because the state only functioned under the leadership of a strong Emperor. 
A series of civil wars wrecked the Empire for a decade. Manzikert led to an unprecedented period of instability. This instability dramatically weakened the grip of the Emperors. Indeed, the Byzantine Empire was only able to stabilize the situation under the capable Emperor Alexius I Comnenos. Still, the lack of an effective government and endemic civil wars allowed the Turks to overrun many Byzantine cities and towns. The Byzantine army had been decimated at Manzikert and it had lost its elite forces. Many of these were impossible to replace as many had been highly trained and experienced cavalry.
To compound the disaster, the loss of the Anatolian Provinces meant that the Byzantines could no longer recruit new soldiers. Provinces such as Cappadocia, which had long supplied the Christian Emperor with recruits were lost to the Turks, forever.  The loss of the Anatolian provinces was also a significant blow to the economy as it dramatically reduced Empire's tax base. The Byzantines were faced constant financial insecurities after Manzikert. It is generally agreed that the defeat in 1071 can be regarded as the beginning of the end of the Byzantine Empire.
The Battle of Manzikert and the Crusades
Byzantine emperor Alexios I Komnenos, concerned about the advances of the Turks in the aftermath of the defeat of Manzikert, sent envoys to the Pope in March 1095 to ask for aid against the Muslims. The Pope, Urban II responded favorably to the request for help from the Byzantines despite the Great Schism that had previously divided the Eastern and the Western Churches. The Pope may have hoped to reunify the Latin and the Greek Orthodox branches of Christianity. However, Urban II decided to urge Christian soldiers to travel to the Byzantine Lands and to fight the Turk and to regain the Holy Lands. This was not what Alexios intended, but soon a huge army of Crusaders was made its way across Byzantine. This army managed to defeat the Turks and eventually conquered Jerusalem. The Crusades, many argue, helped push back the Turks and preserve the remaining lands of the Byzantine Empire. However, the Crusades were to take an unexpected turn. In 1204 the Fourth Crusade was diverted by the Venetians and it captured the Byzantine capital. This betrayal was a devastating blow to the Eastern Christian Empire.
The Byzantine Empire and the West
Because of the loss of the provinces in Anatolia after 1071, the Byzantine Empire sought financial support from the west. The Empire needed to raise revenues and increase its trade. To do this they turned more and more to the West and especially to the rising maritime city-states in Italy, such as Amalfi, Genoa and especially Venice. These republics gradually began to dominate the economy and the trade of the Empire and this led to the decline of the Byzantine navy, which had once been the most feared in the Mediterranean. By 1200, the Italians or ‘Latins’ had their own quarter in Byzantium and had many independent trading colonies in the Empire. Even after 1204 and the treachery of the Fourth Crusade, the Byzantines had no choice but to turn to the Italians and others for help. Manzikert and the resulting loss of the Anatolian provinces led to the Greek Orthodox Empire becoming economically dependent on the Latin West which ultimately undermined its ability to defend itself from its many enemies.
The Birth of Modern Turkey
Prior to the Battle of Manzikert, there had been no Turks in Anatolia. However, in the wake of the victory of Alp Arslan hordes of Turks entered the eastern part of the Byzantine Empire. The defeat leads to dramatic demographic changes in Anatolia. Turkish raiders drove the Greek and other Christian populations westwards and they virtually abandoned the Anatolian plateau to the interlopers. Individual Turkish tribes began to conquer lands after the Seljuk victory.
Members of noble Turkish families began to organize the various Muslim freebooters and raiders and established emirates in the former eastern provinces of Byzantium. They often had good relations with the Byzantine Empire and eventually, a member of the Seljuk royal family established the Sultanate of Rum and broke from the Turkish Empire. During the Sultanate of Rum, many more Turkish nomads settled in Anatolia and the area became increasingly Turkish and Muslim and lost it old Greek and Christian character. Many locals even converted to Islam and adopted the customs of the invaders. The dissolution of the Rum Sultanate in the 14th century left behind many small Turkish principalities, among them that of the Ottoman dynasty. They, established an Empire in the Middle East and eventually capture Byzantium in 1453.
The defeat of Emperor Romanus IV army at Manzikert was a disaster for the Byzantine Empire. Not only did it lead to the collapse of the Eastern Frontier but also a ten-year period of civil war. This led to Turkish raids which resulted in their settlement of Anatolia. The loss of the Eastern provinces meant that the Byzantines military and economic resources were depleted, and this made them vulnerable to their enemies in the east and the west.
As a result, the Empire began to lose even more lands and became dependent on westerners. One consequence of the battle was that a request for help by an Emperor to the Pope that led to the Crusades. The Seljuk victory effectively left the Byzantines as a second-rate- power and an Empire only in name. The loss of the eastern provinces led to a period of irreversible decline for the Christian Eastern Empire. The defeat of the Byzantines at Manzikert allowed the Turks to occupy Anatolia and this led to both the establishment of the Ottoman Empire and ultimately the modern Turkish state.
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