The fall of Constantinople in 1453. Panorama Museum in Istanbul / Alamy
In a series of lectures, the Byzantinist, Iranist and Turkologist Rustam Shukurov tells how Byzantium met, fought and befriended the Turks and how it eventually died at their hands. The final lecture of the course talks about how the Ottoman state fulfilled the prophecy of Islam and conquered an empire two thousand years old.
Despite all the humiliations the Roman Empire faced in its final decades, both Christians and Muslims continued to recognize it as the only legitimate universal power in the world, rooted in its connection to Alexander the Great and the Roman Empire. This universal legitimacy meant that whoever conquered Constantinople inherited this status through the right of war.
For Muslim conquerors, there was an additional aspect influenced by certain hadiths of the Prophet Muhammad, which emphasized the cosmic significance of Constantinople and its conquest in relation to the fulfillment of world history. The Koran also portrayed Rome and Byzantium sympathetically, associating Rome with monotheism. The ‘Surah al-Rum’, the thirtieth chapter of the Koran, predicts the eventual victory of the Romans after their initial defeat by saying, ‘And it will be the day when the believers will rejoice in the victory granted by Allah.’
These verses were revealed during the Byzantine-Persian war in the late 610s when the Byzantines suffered defeat and lost half of their empire to the Persians. Interestingly, some Muslim commentators and Eastern scholars misinterpreted these verses as the promise of victory for the Persians or Muslims. However, the intended recipients of this promise were actually the Christians of the Roman Empire. This surah can be seen as a fulfilled political prediction.
On the other hand, Muhammad's hadith concerning the conquest of Constantinople speaks specifically of Muslims capturing the city after a bloody battle and emphasizes the significance of this event. These hadiths were utilized during the later attempts by Muslims to seize Constantinople in the seventh and eighth centuries. While there is theological debate about the authenticity of these hadiths, they played a role in Muslim ideological discourse whenever conflicts with Byzantium arose.
The conquest of Constantinople in 1453, which fulfilled these hadiths, marked a turning point in the interpretation of these prophecies. The eschatological context of the early interpretations became overshadowed, and the hadiths began to be seen as foretelling the universal power of Islam, particularly through the Ottoman sultans.
Józef Brandt. Fight for a Turkish Standard. 1905 / Photo by: PHAS/Universal Images Group via Getty Images
The Empire is on the defense
In the second half of the fourteenth century, as discussed in the previous lecture, the hadith’s prophecy seemed on the verge of fulfillment as Byzantine-Turkish relations transformed after the intervention of John VI Kantakouzenos. Previously, the rivalry between Byzantium and the Turks had been an active, complex, diverse, and sometimes exhilarating confrontation between equals. Byzantium actively participated in this interconnection, and the protocols of the relationship were established, elaborating and imposing their rules of the game, often with success. This state of affairs persisted even during John VI Kantakouzenos's reign. However, with the arrival of the Ottomans in Thrace, Byzantium transitioned into a state of passivity, becoming an object of external influence and a powerless observer of a hostile environment that held ominous implications for its future.
The prevailing sentiment among those Byzantine individuals who migrated en masse to the West after 1354 was for a change in the fundamental status of the state. While our knowledge of the scale and dynamics of emigration from Late Byzantium in the fourteenth and early fifteenth centuries, as well as its socio-demographic consequences for both the empire and recipient territories, remains limited, this topic warrants the closest attention, despite lacking sufficient research.
The political landscape of the Balkans, characterized by a mixture of Slavic and Greek influences, played a significant role in facilitating the success of the Turks. Following the death of the Serbian king Stefan Dušan in 1355, his kingdom splintered into warring principalities, while the Bulgarian kingdom faced a crisis, being divided into three centers of power: Tarnovo, Vidin, and Karvuna. Byzantium, weakened and demoralized by civil wars, was unable to withstand the ambitious dominance of the Ottomans, who flooded the Balkans, filling the political vacuum.
Byzantine Emperor John VI Palaiologos. Mosaic in the mosque of Aya Sofia. 14th century / David Hendricks// thebyzantinelegacy.com/
The subsequent history of Byzantine-Ottoman relations unfolded as a continuous series of Byzantine defeats and humiliations, which resulted in a painful erosion of their national pride and identity. Recognizing the dire situation, John V Palaiologos (1341–91), as the sole ruler, bore the responsibility for addressing the crisis. During his reign, Byzantium held control over Constantinople, Thessalonica, two regional megalopolises, territories in Thrace and Eastern Macedonia, several islands in the Aegean, a few isolated areas in Anatolia (primarily Philadelphia), and most importantly, Morea, which was perhaps the most successful Byzantine enclave.
Emperor John V visited Hungary, Rome, and Venice. These trips were an extraordinary event, because before John V, none of the Byzantine emperors left the empire of their own free will.
John V, while an active ruler, proved to be far from a strong leader. Initially, his relations with Orhan, a longtime ally of Kantakouzenos, were strained. However, fate provided an opportunity for reconciliation. In 1356, near Nicomedia, pirates captured Prince Halil, the half-Greek son of Orhan and Theodora, by chance. He ended up in the hands of Greek corsairs from Phocaea, causing Orhan great distress. John V played an active role in resolving the situation, even assembling a fleet and laying siege to Phocaea, albeit without success. Halil’s release only occurred in 1358 when the emperor finally paid the demanded ransom of 100,000 hyperpyron (equivalent to about half a ton of Byzantine gold coins, each made of fifty per cent gold, at the time) to the pirates. Upon his return to Constantinople, Halil was engaged to the emperor's daughter Irene (1359), who was then ten years old. This reconciliation with Orhan raised hopes for improved relations.
However, Orhan's son Murad I (1362–89) did not feel bound by treaties. He established his capital in Didimotih (Dimetoka) even before his father's death in 1362. Murad I was an intelligent, successful, and ambitious ruler, eventually adopting the grand title of sultan to replace the humble title of emir. The Ottomans commenced their systematic conquest of strategic cities in Thrace and Macedonia, while Byzantium found itself powerless to resist. The Turks' advance experienced a brief pause with the unexpected campaign of Amadeus VI, Count of Savoy and nephew of Empress Anna of Savoy, a cousin of John V Palaiologos, in 1366. However, this failed to alter the power balance in the Balkans significantly.
Saracens attacking the Byzantines in Edessa. Miniature from the manuscript of the Skylitzis of Madrid. 12th century / Wikimedia Commons
Soon, the Turks captured Adrianople, the empire's third most important city. It is possible that an independent group of Turkic adventurers, rather than Ottoman subjects, seized the citadel. Subsequently (around 1377), the Ottomans made Adrianople their capital. While Orhan chose to remain in Asia, Murad I, despite continuing his conquests in Anatolia, envisioned the future of his state as predominantly a European power.
One of the few notable initiatives during John V's reign was his unprecedented travels to European powers in search of military and monetary aid against the Turks. Between 1366 and 1371, John V embarked on journeys to Hungary, Rome, and Venice, which were extraordinary events, as no Byzantine emperor had voluntarily left the empire before. Despite the emperor's conversion to Catholicism in Rome, his negotiations failed to yield positive results. The personal appeals for help only served to humiliate the empire and its ruler. Two decades later, Emperor Manuel II, John V's son, would undertake similar travels to Venice, France, England, Castile, Aragon, and Rome with the same objectives. In the 1420s, John VIII, Manuel's son, sought assistance from Venice and Hungary.
Janissaries. Illustration from the book "Pictures from the life of Turkish people" by G. Hendrowski. 16th century / Alamy
The Serbs, who had once conquered most of the Balkans during the era of King Stefan Dušan, put up a strong resistance against the Turks. Despite internal conflicts in Serbia and the dissolution of the unified kingdom after Dušan’s death, the Serbs remained the most powerful military force in the Balkans. The Ottoman Turks, expanding their influence in Macedonia, engaged in bloody rivalries with the Serbs. The Battle of the Maritsa River on 26 September 1371 led to the Serbs losing Macedonia, and the Battle of Kosovo on 15 June 1389 resulted in the Ottoman victory over Moravian Serbia. By the early 1380s, the Turks had occupied western Macedonia and invaded Albania. They had also made significant advances into weakened Bulgaria.
Between 1371 and 1376, Byzantium acknowledged its dependence on the Ottoman emirate, which was legally formalized as an unequal alliance. This marked the first time the empire entered into a union as a junior partner. Just as John VI Kantakouzenos had relied on the Turks, John V now had to accept his position as Murad I's junior partner. In a letter written in 1374, Pope Gregory XI expressed his dismay and indignation over this impious alliance between the Greeks and the Turks against Christians, highlighting the significant shift in Byzantine policy and the empire's international status.
For a Byzantine leader seeking a future within Byzantium, there was no choice except to align with the Turks. The Ottoman sultanate became a functional element of Byzantine statehood, and the Byzantine mentality and culture were deeply influenced by this close cohabitation with the Ottomans. Murad I pursued a policy of resettlement by bringing the nomadic Turks (Yörüks) and sedentary Muslims from Anatolia to the Balkans. Retrospective data from Ottoman tax censuses suggest that by the second half of the fourteenth century, Anatolian Muslim settlers (sürgünler) likely comprised between thirty to seventy per cent of the population in certain regions of Thrace and eastern Macedonia, with up to a third of Muslims being nomadic Yörüks. Many of these settlers originated from the Aegean emirates. The resettlement of Anatolian Muslims in the Balkans, including Bulgaria, Thessaly, and Albania, continued into the fifteenth century.
Simultaneously, there was a constant influx of Turkic adventurers and free mercenaries from Anatolia who seized territories in Thrace and Macedonia, plundered the local population, and sold them into slavery. However, in the 1370s, Murad I, and later his successor Bayezid I, made significant efforts to subdue these independent brigands' nests and integrate them into the Ottoman administrative structure. Murad I found a new way to benefit the state from the surplus of slaves obtained during the expansion into densely populated areas of Macedonia and Thrace. Instead of being sold in markets as before, the slaves became a source of military troops as young men were enslaved and enlisted in Ottoman infantry units. This marked the beginning of the renowned Janissary corps, derived from the Turkish word yeñiçeri meaning ‘new army’.
The rapid expansion of the Ottomans in the Balkans left no doubt that Byzantium's existence was nearing its end and the conquest of Constantinople was imminent. The first Turkish siege of Constantinople began in 1394 under Sultan Bayezid I (1389–1402), the son of Murad I, who was nicknamed ‘Yıldırım’, meaning ‘Thunderbolt’, due to his leadership style and explosive, unbalanced character. Constantinople was considered an impregnable stronghold due to its defenses and vastness, covering an area of approximately 10 km2 (in comparison, at that time, Rome and Paris occupied 4–5 km2). However, it soon became apparent that the Turks lacked the experience to besiege such a vast fortified megalopolis. Instead of directly attacking Constantinople, they blockaded the city with large forces, cutting off its land routes and establishing the fortress of Anadolu Hisarı on the Asian side of the Bosporus to control supplies from the Black Sea.
Adam Stefanovic. Battle of Kosovo in 1389. 1870 / Wikimedia Commons
Timur's intervention
The Byzantine emperors’ pleas to the West for help yielded no tangible results. The last pan-European crusade led by the Hungarian king Sigismund gathered a substantial army consisting of Hungarians, French, Burgundians, Germans, and Vlachs, and it included troops from Poland, Bohemia, Italy, England, and even Spain. The Venetians, Genoese, and Rhodesian Hospitallers took on the responsibility of patrolling routes in the Sea of Marmara and the Black Sea and also ventured into the Danube. However, in September 1396, at Nicopolis on the banks of the Danube, Bayezid I decisively defeated the Crusader army. A smaller expedition led by Marshal Boucicaut, sent by the French king Charles VI to assist the Greeks in 1397, had no significant impact on the military and political balance.
However, fate intervened to delay the fall of Byzantium. In 1402, the renowned Central Asian conqueror Timur invaded Anatolia and advanced westward toward Ankara. Recognizing the gravity of the challenge, Bayezid I assembled a massive army and prepared for a great battle. Suddenly, a gigantic comet shaped like a spearhead or torch appeared in the sky, foretelling a universal cataclysm. The Greeks referred to it as the Torchbearer. On 28 July 1402, the momentous Battle of Ankara took place. The Ottoman army was completely annihilated, and Bayezid was taken captive by Timur. The Ottomans not only lacked loyal allies in this war but also their own army was disloyal to their sultan. Units recruited from the recently conquered Anatolian lands of Saruhan, Aydin, Mentesh, and Germiyanids abandoned Bayezid and joined Timur's side during the battle. Although Bayezid I was held with due honor, he soon died in captivity. This marked the end of the first Turkish siege of Constantinople.
Timur's defeat of the Ottoman sultanate granted Constantinople a reprieve of several decades. Bayezid died, and his sons engaged in a civil war that persisted for more than ten years, and Mehmed I (1413–21), one of his sons, emerged victorious from the internal conflict. Later Ottoman historians would refer to this period as fetret devri, meaning ‘the time of depression’. However, the Byzantine attempts to exploit the Turks' defeat and bolster their own power yielded no significant success; the capabilities of the two sides were not comparable. The prolonged crisis did not dismantle the Ottoman state, highlighting its remarkable resilience. Interestingly, in the personal communication between Byzantine emperor Manuel II and Sultan Mehmed I, one could discern mutual personal sympathy alongside their legitimate rivalry. In his will, Mehmed I appointed Manuel II as the guardian of his two young sons, Mahmud and Yusuf, who were eight and seven years old at the time. The Turk entrusted the Greek emperor with this responsibility, presumably having his own reasons for doing so.
Stanislav Khlebovsky. Sultan Bayezid prisoned by Timur. 1878 / Wikimedia Commons
However, with a new generation of rulers—Sultan Murad II (1421–51) and the burgeoning influence of the young John VIII, son of Manuel—another phase of enmity commenced. The new generation of rulers in both states exhibited far greater radicalism than their predecessors and desired more assertiveness and victories. Naturally, they sought to adopt a tougher stance toward their political rivals. The simultaneous generational shift in the Byzantine and Ottoman courts brought about a dramatic change in Greek-Turkish relations, effectively extinguishing any hopes of a Byzantine revival.
Murad I escalated pressure on the Greeks from the early stages of his reign. He besieged Constantinople for several months, even though the Ottomans lacked the necessary equipment and skills to pose a genuine threat to the city. In addition, he blockaded Thessalonica and invaded Byzantine Morea. Unable to defend Thessalonica, the second-most important center of the empire, the Byzantines were compelled to sell the city to the Venetians. Murad II's vigorous campaigns swiftly nullified nearly all the advantages the Byzantine Empire had gained after the Battle of Ankara, forcing them to acknowledge the Sultanate's supremacy through a treaty once again. The endeavors of the Western Europeans to halt the Turkish onslaught culminated in another defeat near Varna in 1444 as Murad II decisively vanquished the combined forces of the Venetians, Hungarians, and Poles. Subsequent attempts by Christian troops to seek revenge resulted in yet another devastating loss at the Second Battle of Kosovo in 1448. Following these defeats, the European powers stopped trying to wrest the Balkans from the Turks.
The Fall of Constantinople
By the end of Murad II's reign, the Ottoman sultanate had reclaimed its position as the foremost political and economic power in the northeastern Mediterranean, boasting an administrative system tailored to perpetual warfare. Both the Ottoman sultanate and the Palaiologos Empire witnessed changes in ruling authority every two years. In March 1449, following the demise of John VIII, his younger brother Constantine XI, the Despot of Morea, ascended the throne. Constantine adeptly governed Morea and completed the Byzantine reconquest of the Peloponnese. In the winter of 1451, Murad II passed away, and his son Mehmed II assumed the title of Ottoman Sultan in early February 1451. Mehmed had been groomed to be sultan by his father's experienced courtiers in the 1440s. However, Murad II had to resume active rule of the country on the eve of the Battle of Varna. At the time of his succession in February 1451, the young sultan was not yet eighteen years old, while his Byzantine adversary Constantine XI was already forty-six, a seasoned politician and military leader.
By this point, Turkish holdings had tightly encircled Constantinople, and the logic of Ottoman conquest left little doubt about the city's imminent fall. Aside from Constantinople, the Byzantines still retained several fortresses in Thrace along the Sea of Marmara and the Black Sea coast, located a few dozen kilometers from the capital. The Christian West appeared resigned to the inevitable collapse of Constantinople, contemplating the reinforcement of new frontiers to halt an Ottoman invasion into Europe. The Turks shared this assessment of Constantinople's prospects. Moreover, being situated behind such a formidable and vast stronghold as Constantinople restricted the Turks' actions throughout the region, both in the Balkans and on the Black Sea. The young sultan regarded the conquest of this citadel as his first great achievement.
On 29 May 1453, Constantinople fell to the Turks, leaving an indelible mark on both the Christian and Muslim worlds. The magnitude of this event and the global response it elicited resulted in numerous accounts being recorded in various languages, spanning different genres, including narratives by professional historians and diplomats, official documents, and folkloric lamentations about the great city.
Gentile Bellini. Ottoman Sultan Mehmed II Fatih. 1480 / Photo by: Pictures From History/Universal Images Group via Getty Images
By the early 1450s, Constantinople had become a sad and dismal sight to behold. In the preceding decades, efforts had been made to maintain the city's fortifications through wall repairs and ditch clearance. However, the urban structures within had deteriorated and fallen into complete disrepair. As people fled the doomed citadel, the population had also dwindled. While Constantinople's population may have exceeded half a million in the past, at the time of its fall, it comprised no more than 50,000 individuals. Nonetheless, Constantinople still stood as one of the largest concentrations of people in Christian Europe.
The palaces, churches, and other public buildings that had been symbols of beauty and luxury had now fallen into decay and disrepair. Even the city's center, including the renowned Hippodrome, lay in ruins. Despite this, the Byzantines continued to care for the Church of St Sophia. Large sections within the city walls had been abandoned or transformed into gardens and orchards, while the coastal quarters remained more densely populated. The impoverished inhabitants of the city no longer possessed the wealth and extravagant attire for which they were once known.
After the unsuccessful sieges of 1394–1402 and 1422, the Turks refrained from attacking Constantinople in subsequent years, acknowledging the impregnability of its fortifications, which remained the most formidable and extensive across the Mediterranean. However, drawing from past experiences, Mehmed II began systematic preparations for the impending siege. The sultan wasted no time and commenced the construction of the Rumelihisarı Fortress on the European side of the Bosporus in April 1452, directly opposite the Anadoluhisarı Fortress that Bayezid I had built on the Asian side. These two fortresses, armed with heavy and light artillery, effectively blocked the Bosporus, preventing the supply of provisions and any other aid from the Black Sea to Constantinople.
Despite his youth, the sultan possessed clear ideas regarding the preparations for the siege. He reformed the Janissary corps by replacing influential commanders with his own appointees. Additionally, he ensured the unwavering loyalty of the Janissaries by introducing a loyal palace guard, the sekban (derived from the Persian sagbān meaning ‘dog keeper’). Mehmed II established regular artillery units, structurally distinguishing them as independent troops. To bolster their artillery, he enlisted the services of Europeans, such as the Hungarian (or Transylvanian) artisan Urban, who had defected to the Turks from the Byzantines. The sultan established workshops in Edirne (Adrianople), where artillery pieces were manufactured and tested. Soon, the Ottomans possessed around a hundred sieges, fortresses, and field guns. Equally significant was the sultan's emphasis on achieving naval superiority. He swiftly constructed over a hundred seagoing vessels, consisting primarily of small ships and around twenty medium-sized galleys. Mehmed did not possess large warships of the galleon type, which was most likely due to a scarcity of skilled shipbuilders.
The Janissaries. Ottoman miniature of the 16th century / Alamy
Constantine XI found himself limited in what he could do in this dire situation. The Basileus took measures to stockpile food and weapons as well as rebuild the city's walls. He also sent out pleas for help to neighboring regions. The responsibility of commanding the defense and protecting vulnerable sections of the walls fell to the Genoese commander Giovanni Giustiniani. Known for his expertise as a condottiere, corsair, and defender of cities, Captain Giustiniani led a force consisting of 400 Genoese and 300 Greeks from Genoa, Chios, and Rhodes. Additionally, several thousand Greeks, small groups of Venetians and Catalans, and individual volunteers from various countries, including some Ottoman Turks, joined in the defense. A fleet of twenty-six ships, primarily Byzantine and Venetian, guarded the Golden Horn. Overall, the defenders numbered around 6,000–7,000 men.
In early April 1453, the Turkish army approached Constantinople. The Ottoman forces consisted of approximately 80–100,000 soldiers, although the accounts from contemporaries varied, often exaggerating the number of Turks. Toward the end of March, a massive Ottoman fleet entered the Sea of Marmara, striking fear into the hearts of the city's inhabitants.
The Ottoman siege endured for two intense months. The Turks used their heavy artillery to destroy the walls of Constantinople and launched periodic infantry attacks through gaps created by gunfire. However, they were unable to breach the city. The defenders, comprising professional soldiers, mercenaries, and well-armed citizens with light firearms and armor, proved more effective in combat despite their smaller numbers. The citizens actively participated in the defense, swiftly blocking gaps in the walls with impassable debris. Turkish infantry assaults on the walls resulted in heavy losses for the attackers.
The Turks then attempted new tactics, using mine warfare to undermine the fortress walls through underground tunnels. However, the defenders included a skilled individual named Grant, possibly of German or Scottish origin, whose expertise and intuition thwarted the Turks' efforts in this regard as well.
At sea, the Turks faced even greater challenges. Mehmed II's attempt to deal with a small Christian fleet failed, leading the Turks to avoid direct naval confrontation and resort to an external blockade of the city. One notable success for Mehmed II was the breakthrough of the Turkish fleet into the Golden Horn from the Bosporus. The Ottomans moved fifty to seventy ships over a wooden platform and armed them with artillery, bombarding the city from the Golden Horn.
By the end of May 1453, both sides were both physically and mentally exhausted. The relentless attacks from the enemy on multiple fronts had drained the strength of the few defenders. Cut off from information from the outside world, the besieged had lost hope of assistance from the Venetian fleet, believing that Christendom had abandoned them (unbeknownst to them, a powerful Venetian fleet was already en route to Constantinople). Pessimism also permeated the Turkish camp, with influential courtiers urging the young sultan to lift the siege.
The Assassination of the Emperor / Qalam
In the last week of May, Mehmed II made the decision to launch one final, decisive assault. The Turks began the battle on Tuesday 29 May after midnight. Given the circumstances, Mehmed II chose the easiest and most sensible tactic: a simultaneous attack along the entire length of the land walls and from the city shore facing the Sea of Marmara. The assault unfolded in three stages. The first stage involved the azebs, the light infantry, who were the weakest part of the army and were largely repelled by Giustiniani's forces. Following the failure of the azeb attack, Mehmed II sent in the Anatolian contingents, a more organized group of efficient soldiers. However, they too made little progress. Finally, after wearing down the enemy, Mehmed II unleashed the elite Janissary units in a relentless assault. After hours of continuous fighting, they finally succeeded. The Ottomans breached Constantinople at the gates of St. Romanus (now Topkapı) and flooded the city in large numbers.
The breach occurred shortly after sunrise, and as word spread, the defenses of the city crumbled. Soldiers and civilians hurried toward the Golden Horn, seeking access to the few ships in the harbor. Over the course of three days, the city experienced the brutal aftermath of war, experiencing looting and the rape, murder, and enslavement of its inhabitants. The Ottoman soldiers and sailors immediately sought their spoils upon the city's fall, allowing many defenders and residents to escape unhindered, both by land and by sea. Following the capture of Constantinople, Mehmed II earned the honorary title ‘Fatih’, meaning ‘Conqueror’ in Arabic.
Stanisław Chlebowski. Mehmed II's entry into Constantinople. 1878 / Wikimedia Commons
The fate of the last Roman emperor remains unknown. According to Greek and Italian accounts, Constantine XI and his comrades fell in battle near the gates of St. Romanus as the Turks breached the city’s final defenses. However, the Turkish historian Tursun Bey reported that the emperor managed to escape the city with a few attendants. While on one of the streets leading toward the Golden Horn, they encountered a group of azebs. In the ensuing fight, the emperor and some of his men were killed, while others were taken as prisoners. The azebs seized a considerable amount of money and precious stones.
In the years that followed, Mehmed II completed the conquest of Byzantine territories. However, the Palaiologan Morea and the Great Komnenos Trebizond, the ruling dynasties of these regions, would inevitably make claims to restore the empire as they had done in Byzantine history. This would further compound the strategic confrontation between the Ottoman sultanate and the Christian world. Recognizing this, Mehmed II aimed to swiftly address the issue of the potential heirs to the empire. In May 1460, seven years after the fall of Constantinople, Ottoman forces captured Mystras, the capital of Byzantine possessions in the Peloponnese. During the summer of 1461, Mehmed II launched a large-scale campaign to the northeast of Anatolia, reaching the borders of the Empire of Trebizond. On 15 August 1461, the city surrendered to the Ottomans through a treaty.
And thus ended the history of the Roman Empire.