The foreign relations of the Byzantine Empire were conducted by the emperor. Preferring diplomacy over war, the emperor would use alliances, treaty's and diplomatic tactics to achieve goals. Military confrontations also occurred, with Dimitri Obolensky calling it as a form of "defensive imperialism". The conduct of its foreign relations is a large factor to the Empire's longevity of 1,123 years.
Overview The Empire's longevity has been said to be due to its aggressive diplomacy in negotiating treaties, the formation of alliances, and partnerships with the enemies of its enemies Even when it had more resources and less threats in the 6th century, the costs of defense were enormous; foreign affairs had become more multi-polar, complex and interconnected; further the challenges in protecting the empire's primarily agricultural income as well as numerous aggressive neighbors made avoiding war a preferred strategy.
The primary objective was survival, not conquest, and the foreign relations strategy was fundamentally defensive or as Dimitri Obolensky has claimed "defensive imperialism".
Between the 4th and 8th centuries, the Empire's leveraged its status as Orbis Romanus and sophistication as a state, which influenced the formation of new settlements on former Roman territories. Relations with Muslim states were more centred around war. Telemachos Lounghis notes that relations with Western Europe became more challenging from 752/3 and later with the Crusades, as the balance of power shifted. A change in policies by emperors in the 9th and early 10th centuries laid the groundwork for future activity which included involved halting, reversing, and attacking Muslim power; cultivating relations and alliances with Armenians and Rus; and subjugating the Bulgarians. By the late era, Militant Islam threatened the state geographically and Latin Christians challenged it economically.
East Roman and Persian-Turk relations Göktürk relations: 6th–7th centuries
The Göktürks of the First Turkic Khaganate, which came to prominence in 552 CE, were the first Turkic state to use the name Türk politically. They played a major role with the East Roman Empire's relationship with the Persian Sasanian Empire. The first contact is believed to be 563 and relates to the incident in 558 where the slaves of the Turks (the Pannonian Avars) ran away during their war with the Hephthalites.
The second contact occurred when Maniah, a Sogdian diplomat, convinced Istämi (known as Silziboulos in Greek writingsEliot, C. (1908). Turkey in Europe. United Kingdom: E. Arnold. Page 76) of the Göktürks to send an embassy directly to the East Roman Empire's capital Constantinople, which arrived in 568 and offered silk as a gift to emperor Justin II. While the Sogdians were only interested in trade, the Turks in the embassy proposed an alliance against the Persians which Justin agreed to. The Persians had previously broken their alliance with the Turks due to the competitive threat they represented. This alliance guaranteed the arrival of west-bound silks from China and increased the risk of a war on two fronts for the Persians, with hostilities that would eventuate with the Byzantine–Sasanian War of 572–591. In 569 an embassy led by Zemarchus occurred which was well received and likely solidified their alliance for war.
Another set of embassies occurred in 575–576 led by Valentine which were received with hostility by Turxanthos due to alleged treachery. They required the members of the East Roman delegation at the funeral of Istämi to lacerate their faces to humiliate them. The subsequent hostility shown by the new ruler Tardu would be matched in East Roman writings.Maurice, Strategikon, ed. Dennis and Gamillscheg, 360; With the insults reflecting a breakdown of the alliance, the likely cause is that the anger was due to the Turks not having their expectations met from their agreements and realising they were being used when they no longer aligned with the current goals of the East Roman Empire (who correspondingly lacked trust in the Turks as partners).
Years later, they would collaborate again when their interest aligned. The Turks attacked the Avars when they sacked an East Roman city in the Balkans (Anchialos in 584). Toward the end of the Byzantine–Sasanian War of 602–628, the Turks allied with the East Roman Empire and played a decisive role with the Third Perso-Turkic War.
Sasanian Persian relations: 3rd–7th centuries
The Sasanian Empire succeeded the Parthian Empire, the traditional arch-rival of the Roman Empire. They were recognized as one of the leading world powers alongside its main rival the East Roman Empire. This was from the overthrow of the Parthian dynasty in the 3rd century by Ardashir I until their total collapse against the Arabs.Norman A. Stillman The Jews of Arab Lands pp 22 Jewish Publication Society, 1979 There would be many wars between the rivals during this period.
The East Roman Empire's final war weakened the Sasanian Empire which set up its destruction by the Arabs. The Byzantine–Sasanian War of 602–628, which included the siege of the East Roman capital Constantinople, ended with both sides having drastically exhausted their human and material resources. In 627, allied with Turks, Heraclius invaded the heartland of Persia. A civil war broke out in Persia, during which the Persians killed their king, and sued for peace. By the end of the conflict, both sides were weakened. Consequently, they were vulnerable to the sudden emergence of the Islamic Rashidun Caliphate, whose forces invaded both empires only a few years after the war. The Muslim armies swiftly conquered the entire Sasanian Empire as well as the East Roman territories in the Levant, the Caucasus, Egypt, and North Africa.
Seljuk relations: 11th–13th centuries
The Seljuk Turks was a Sunni Muslim dynasty from the Qiniq branch of the Oghuz Turks. They gradually became Persianate and contributed to the Turco-Persian traditionGrousset, Rene, The Empire of the Steppes, (Rutgers University Press, 1991), 161,164; "renewed the Seljuk attempt to found a great Turko-Persian empire in eastern Iran..", "It is to be noted that the Seljuks, those Turkomans who became sultans of Persia, did not Turkify Persia-no doubt because they did not wish to do so. On the contrary, it was they who voluntarily became Persians and who, in the manner of the great old Sassanid kings, strove to protect the Iranian populations from the plundering of Ghuzz bands and save Iranian culture from the Turkoman menace."Nishapuri, Zahir al-Din Nishapuri (2001), "The History of the Seljuq Turks from the Jami' al-Tawarikh: An Ilkhanid Adaptation of the Saljuq-nama of Zahir al-Din Nishapuri," Partial tr. K.A. Luther, ed. C.E. Bosworth, Richmond, UK. K.A. Luther, p. 9: "[T]he Turks were illiterate and uncultivated when they arrived in Khurasan and had to depend on Iranian scribes, poets, jurists and theologians to man the institution of the Empire" in the medieval Middle East and Central Asia. The Seljuks established both the Seljuk Empire and the Sultanate of Rum, which at their heights stretched from modern day Iran to Anatolia, and were targets of the First Crusade.
After the conquest of territories in present-day Iran by the Seljuq Empire, a large number of Oghuz Turks arrived on the East Roman Empire's borderlands of Armenia in the late 1040s. Eager for plunder and distinction in the path of jihad, they began raiding the East Roman provinces in Armenia. At the same time, the eastern defenses of the East Roman Empire had been weakened by Emperor Constantine IX Monomachos (), who allowed the thematic troops (provincial levies) of Iberia and Mesopotamia to relinquish their military obligations in favour of tax payments. As a consequence of this invasion, the Battle of Kapetron occurred in 1048.
Over the next century, the Byzantine and Seljuk armies would fight many battles, with the Battle of Manzikert in 1071 considered a turning point in the history of Anatolia. The legacy of this defeat would be the loss of the East Roman Empire's Anatolian heartland."The defeat in August 1071 of the East Roman emperor Romanos Diogenes by the Turkomans at the battle of Malazgirt (Manzikert) is taken as a turning point in the history of Anatolia and the East Roman Empire. From this time the East Romans were unable to stem the flow of the Turks into Anatolia and the slow process of Turkification had begun." The battle itself did not directly change the balance of power between the East Romans and the Seljuks; however the ensuing civil war within the East Roman Empire did, to the advantage of the Seljuks.
Emperor Alexios I Komnenos sent envoys that would have a large impact on history. He was worried about the advances of the Seljuks in the aftermath of the Battle of Manzikert of 1071, who had reached as far west as Nicaea, and sent envoys to the Council of Piacenza in March 1095 to ask Pope Urban II for aid against the invading Turks.Blumenthal, Uta-Renate (2006). "Piacenza, Council of (1095)". In The Crusades – An Encyclopedia. pp. 956–957. What followed was the First Crusade. The Seljuk sultans bore the brunt of the Crusades and eventually succumbed to the Mongol invasion at the 1243 Battle of Köse Dağ. For the remainder of the 13th century, the Seljuks acted as vassals of the Ilkhanate.John Joseph Saunders, The History of the Mongol Conquests, (University of Pennsylvania Press, 1971), 79. Their power disintegrated during the second half of the 13th century. The last of the Seljuk vassal sultans of the Ilkhanate, Mesud II, was murdered in 1308.
Ottoman relations: 13th–15th centuries
The dissolution of the Seljuk state left behind many small Turkish principalities. Among them were the Ottoman dynasty, which originated from the Kayı tribe branch of the Oghuz Turks in 1299, and which eventually conquered the rest and reunited Anatolia to become the Ottoman Empire. Over the next 150 years, the Byzantine–Ottoman wars were a series of decisive conflicts between the Ottoman Turks and Byzantine Romans that led to the final destruction of the Byzantine Empire and the dominance of the Ottoman Empire.
In 1453, the Ottoman Empire conquered Constantinople, the capital city of the East Roman Empire. They followed by conquering its splinter states, such as the Despotate of the Morea in 1460, the Empire of Trebizond in 1461, and the Principality of Theodoro in 1475.
East Roman and Arab relations
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 at the Battle of Lalakaon 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 the Abbasid Caliphate started military excursions culminating with a victory in the Sack of Amorium. The East Romans counter-attacked and sacked Damietta in Egypt. The Abbasid Caliphate responded by sending troops into Anatolia again, sacking and marauding until they were eventually annihilated by the East Romans at the Battle of Lalakaon in 863.
In the early years of Basil I's reign, Arab raids on the coasts of Dalmatia and the siege of Ragusa (866–868) were defeated, and the region once again came under secure East Roman control. This enabled East Roman missionaries to penetrate to the interior and convert the Serbs and the principalities of modern-day Herzegovina and Montenegro to Christianity..