The Byzantine–Seljuk wars were a series of conflicts in the Middle Ages between the Byzantine Empire and the Seljuk Empire. They shifted the balance of power in Asia Minor, Armenia and Syria, sparking multiple wars for control over these regions, including the Crusades. These conflicts lasted until the collapse of the Sultanate of Rum in 1308.
The Battle of Manzikert of 1071 is widely regarded as the turning point of the wars. The battle opened up Anatolia for further Turkoman raids, migrations and settlements. The Byzantine military had declined in manpower and equipment prior to 1071, with constant Turkoman incursions overrunning the failing Thematic System. After Manzikert, Byzantine rule over Asia Minor did not end immediately, nor were any heavy concessions levied by the Seljuks on their opponents. It took another two decades before the Seljuks, Turkomans, Danishmendids and Chaka were in control of most of the Anatolian peninsula, before they were repulsed from the coastlines.
During the course of the war, the Seljuks and their allies attacked the Fatimid Caliphate of Egypt, capturing the religious center of Jerusalem and catalyzing the call for the First Crusade by Pope Urban II, after Alexios I Komnenos asked for military assistance. Within a hundred years, the Byzantines had successfully driven back the Seljuks from the coasts of Asia Minor and extended their influence to the Levant. Following the Fourth Crusade however, and the sack of Constantinople in 1204, the Byzantine Empire became fractured, beginning the Struggle for Constantinople. Before the conflict ended, the Seljuks managed to raid and conquer more territory from the weakened Empire of Nicaea, until the Sultanate itself was taken over by the Mongols, leading to the fall of Rum and the rise of the Ghazis, and the conclusive Byzantine–Ottoman wars.
Origins
The decades following the death of the Byzantine emperor Basil II saw a long series of instability and a weakening of imperial authority and military power, which led to a succession crisis. At the same time, the efforts to restrain the ambitious provincial aristocrats and military magnates, kept at bay during Basil II's reign, failed. With the successes of the late 10th and early 11th centuries, the spoils of war saw the enrichment of the military aristocracy, which sparked a struggle for political power and influence within the state, as the dynatoi sought to absorb the free peasantry and the free landholdings. Imperial bureaucrats sought to reduce the power and likelihood of the military aristocracy to launch rebellions, by dismissing generals, dissolving entire military corps and cutting off the financial support of the local troops forming the thematic levies. This further put strain on the manpower needed to defend imperial territory. The state increasingly relied on mercenaries, but these highly ambitious soldiers were often unreliable and prone to mutinies.
Constantine IX was blamed by contemporaries for his policy of fiscalization or full demobilisation of a large portion of the Empire's eastern standing army. John Skylitzes, Kekaumenos, and Michael Attaleiates accuse Constantine of dismantling the army of the Iberian Theme, permanently dismissing 50,000 standing troops in Armenia, relieving them of their military duties at the moment the state begun to be faced with Seljuk raids.
For the next few decades, the Byzantine Empire saw a series of rebellions, including those of Gregory Taronites, Peter Delyan, Theophilos Erotkos, George Maniakes, Leo Tornikios, Hervé Frankopoulos, Isaac Komnenos and Nikoulitzas Delphinas. With the rebellion of Isaac Komnenos being one of the most decisive, as it saw the destruction of much the Byzantine Empire's most influential generals at the Battle of Hades. These civil wars caused the thematic armies to be drawn west or east, depending on the rebellion, and opened the borders to incursions by the Normans, Serbs, Hungarians, Pechenegs, Seljuks, or the mercenaries roaming in Anatolia.
As the Byzantines were making headway against the Arabs in the 10th century, Persia was being ruled by the Ghaznavid Empire. The migration of the Seljuks into Persia in the 10th century led to the Ghaznavids being overthrown. The Seljuks settled and adopted Persian language and customs.C. Edmund Bosworth, "Ghaznavids". Encyclopædia Iranica, Vol. X, Fasc. 6, pp. 578-583. Their first encounter with the Byzantine Empire was in the Battle of Kapetron in 1048, where they were repulsed. Nevertheless, the Seljuks established a powerful domain and captured Baghdad in 1055 from the Abbasid Caliphate.Christie, Niall (2006). "Abbāsids". In The Crusades - An Encyclopedia. pp. 1-3. The Abbasids were henceforth a mere figurehead in the Islamic world. The Seljuks, spurred on by their previous success, launched an attack on the Levant and against Fatimid Egypt, which lost Jerusalem in 1071.Cahen, Claude (1969). "Chapter V. The Turkish Invasion: The Selchükids." In Setton, Kenneth M.; Baldwin, Marshall W. (eds.). A History of the Crusades Vol. I: The First Hundred Years. Madison: The University of Wisconsin Press. pp. 99-132.
By the time the Seljuks begun to intensify their attacks in Anatolia, Byzantium was faced with civil wars, Norman conquests,Edmund Curtis (1911). "Robert Guiscard". In Chisholm, Hugh (ed.). Encyclopædia Britannica. 23. (11th ed.), Cambridge University Press. pp. 400-401. Serbian revolts, Pecheneg revolts, and the Great Schism, whilst the Abbasid Caliphate had been severely weakened due to its wars against the Fatimid dynasty.Gibb, Hamilton H. A. (1969). "Chapter III. The Caliphate and the Arab States". In Setton, Kenneth M.; Baldwin, Marshall W. (eds.). A History of the Crusades: Volume One. The First Hundred Years. Madison: The University of Wisconsin Press. pp. 81-98.
Initial conflicts: 1048–1071
In 18 September 1048, hostilities begun when the Battle of Kapetron was fought by the half-brother of the Sultan Tughril I, Ibrahim Inal, against the Byzantine Empire and the Duchy of Kldekari. In 1054, the Sultan himself besieged Manzikert, but the defenders, led by Basil Apokapes, defeated the Seljuks. Ever since early in the 11th century, the Seljuk Turks from central Asia had been expanding westward,Brett, Michael (2006). "Saljūqs". In The Crusades - An Encyclopedia. pp. 1064-1068. defeating various Arab factions and occupying the Abbasid caliphate's power base in Baghdad.C. Edmund Bosworth, "Abbasic Caliphate". Encyclopædia Iranica, Vol. I, Fasc. 1, pp. 89-95.
Following the ascension of Alp Arslan to the Seljuk throne, a series of raids were launched against Byzantine possessions in Asia Minor, Armenia and Cilicia, as prominent cities, including those of Ani, Caesarea, Neocaesarea, Amorium, Iconium and Chonae, were sacked and pillaged by the Turks.. Two Byzantine counterattacks in 1068 and 1069 temporarily drove the Seljuks back from these lands and even captured the city of Hierapolis from the Mirdasids, who were allies of the Seljuks. Further offensives by the Byzantine army drove the Turks back across the Euphrates.El-Azhari, T. Kamal (1997). The Saljūqs of Syria: during the Crusades, 463-549 A.H./1070-1154 A.D. Berlin: K. Schwarz.
Despite this, the Seljuks continued their incursions into Anatolia, capturing Manzikert. The Byzantine Emperor Romanos IV Diogenes led an army in an attempt to score a decisive blow against the Seljuks and add legitimacy to his rule. During the march, Alp Arslan withdrew from Manzikert. His tactical withdrawal allowed his army to ambush the Byzantines, winning the decisive Battle of Manzikert on 26 August 1071.Morris, Rosemary (2006). "[Mantzikert, Battle of (1071)". In The Crusades - An Encyclopedia. pp. 795-796. The victory itself led to few gains at the time for the Seljuks, but the civil wars that resulted in the Byzantine Empire, combined with an uprising in Bulgaria and the rebellion of Roussel de Bailleul, allowed the Seljuks, the Danishmendids and various other Turkomans to swarm into Asia Minor.Orient et Occident à la fin du XI siècle. In Cahen, C. La Syrie du nord à l'époque des croisades et la principauté franque d'Antioche (1940). Paris: P. Geuthner.
Turkic conquests: 1071–1096
After Manzikert, the Seljuk Turks concentrated on their eastern territorial gains which were threatened by the Fatimid dynasty in Egypt although Alp Arslan encouraged other allied Turks and vassals to establish Beyliks in Asia Minor.Kaldellis, Anthony, Streams of Gold, Rivers of Blood: The Rise and Fall of Byzantium, 955 A.D. to the First Crusade. (Onassis Series in Hellenic Culture), Oxford University Press, 2017 Many Byzantines at the time did not see the victory as a total disaster and when the Turks began occupying the countryside in Anatolia they began to garrison the Byzantine cities as well, not as foreign conquerors but as mercenaries requested by various Byzantine factions – one Byzantine Emperor even gave the city of Nicaea's defense to the invading Turks in 1078.
The result of the civil war meant that pretenders to the Byzantine throne sought Turkic aid by conceding Byzantine territory. The loss of these cities such as Nicaea and another defeat in Anatolia led to a prolongation of the war. The civil conflict finally ended when Alexius I Komnenos, who had been leading Imperial armies to defeat revolts in Asia Minor became a rebel himself and seized the Byzantine throne in 1081. Despite emergency reforms implemented by Alexius, Antioch and Smyrna were lost by 1084.Charanis, Peter (1969). "Chapter VI. The Byzantine Empire in the Eleventh Century." In Setton, Kenneth M.; Baldwin, Marshall W. (eds.). A History of the Crusades Vol. I: The First Hundred Years. Madison: The University of Wisconsin Press. pp. 99-132. However, between 1078 and 1084 Antioch had been in the hands of Philaretos Brachamios, an Armenian renegade. By 1091, the few remaining Byzantine towns in Asia Minor inherited by Alexius were lost as well. However, all was not to end in defeat for Byzantium; in 1091, a combined Seljuk/Pecheneg invasion and siege of Constantinople was thoroughly defeated whilst the Norman invasions had been held back as well allowing the Empire to focus its energies against the Turks. The Byzantines were thus able to recover the Aegean islands from Tzachas and destroy his fleet, and even regain the southern littoral of the Marmara Sea in 1094.
In 1094, Alexius Comnenus sent a message to Pope Urban II asking for weapons, supplies and skilled troops. At the Council of Clermont in 1095, the Pope preached a Crusade to be undertaken in order to capture Jerusalem and, in the process, assist the Byzantine Empire which could no longer guard Christendom in the East from Islamic aggression.Munro, Dana Carleton. (1906). The speech of Pope Urban II. at Clermont, 1095. [New York. Though the Crusades would assist the Byzantine Empire in reconquering many vital Anatolian towns, it also led to the dissolution of the Empire in 1204 during which time the Byzantines struggled to hold on to their territories.
Byzantium survives: 1096–1118
The first Crusaders arrived in 1096 following Alexius' appeal to the West.. The agreement between the Byzantines and the Crusaders was that any Byzantine cities re-captured from the Turks would be handed over to the Empire..