Byzantine Empire: Palaiologos dynasty

Michael VIII Palaiologos's reign saw considerable recovery of Byzantine power, including the enlargement of the Byzantine army and navy. It would also include the reconstruction of the city of Constantinople, and the increase of its population. He reestablished the University of Constantinople, which led to what is regarded as the Palaiologan Renaissance between the 13th and 15th centuries. It was also at this time that the focus of the Byzantine military shifted to the Balkans, against the Bulgarians, leaving the Anatolian frontier neglected. His successors could not compensate for this change of focus, and both the Arsenite schism and two civil wars (the Byzantine civil war of 1321–1328, and the Byzantine civil war of 1341–1347) undermined further efforts toward territorial consolidation and recovery, draining the empire's strength, economy, and resources. Regular conflict between Byzantine successor states such as the Empire of Thessalonica, Trebizond, Epirus and Serbia resulted in permanent fragmentation of former Byzantine territory and opportunity for increasingly successful conquests of expansive territories by post-Seljuk Anatolian beyliks, most notably that of Osman, later called the Ottoman Empire.

At the Battle of Pelagonia (1259), the forces of the Byzantine emperor Michael VIII Palaiologos (r. 1259–1282) killed or captured most of the Latin nobles of the Principality of Achaea, including the Prince William II of Villehardouin (r. 1246–1278). In exchange for his freedom, William agreed to hand over a number of fortresses in the southeastern part of the Morea peninsula. He also swore an oath of allegiance to Michael, becoming his vassal and being honoured by becoming godfather to one of Michael's sons and receiving the title and position of grand domestic. In early 1262, William was released, and the forts of Monemvasia and Mystras, as well as the district of Mani, were handed over to the Byzantines.

In late 1262, William visited the region of Laconia accompanied by an armed retinue. Despite his concessions to the Byzantines, he still retained control of most of Laconia, in particular the city of Lacedaemon (Sparta) and the baronies of Passavant (Passavas) and Geraki. This display of armed strength worried the Byzantine garrisons, and the local governor, Michael Kantakouzenos, sent to Emperor Michael to ask for aid.

The Battle of Prinitza was fought in 1263 between the forces of the Byzantine Empire, marching to capture Andravida, the capital of the Latin Principality of Achaea, and a small Achaean force. The Achaeans launched a surprise attack on the greatly superior and overconfident Byzantine force, defeated and scattered it, saving the principality from conquest.

The Battle of Settepozzi was fought in the first half of 1263 off the island of Settepozzi (the medieval Italian name for Spetses) between a Genoese–Byzantine fleet and a smaller Venetian fleet. Genoa and the Byzantines had been allied against Venice since the Treaty of Nymphaeum in 1261, while Genoa, in particular, had been engaged in the War of Saint Sabas against Venice from 1256. In 1263, a Genoese fleet of 48 ships, which was sailing to the Byzantine stronghold of Monemvasia, encountered a Venetian fleet of 32 ships. The Genoese decided to attack, but only two of the four admirals of the Genoese fleet, and 14 of its ships took part and were easily routed by the Venetians, who captured four vessels and inflicted considerable casualties.

The Venetian victory and the demonstration of Genoese reluctance to confront them had important political repercussions, as the Byzantines began to distance themselves from their alliance with Genoa and restored their relations with Venice, concluding a five-year non-aggression pact in 1268. After Settepozzi, the Genoese avoided confrontation with the Venetian navy, instead focusing on commerce raiding. This did not prevent another, even more, lopsided and complete defeat at the Battle of Trapani in 1266.

After the Battle of Prinitza, Constantine Palaiologos regrouped his forces, and in the next year launched another campaign to conquer Achaea. His efforts, however, were thwarted, and the Turkish mercenaries, complaining of lack of pay, defected to the Achaeans. William II then attacked the weakened Byzantines and achieved a major victory at the Battle of Makryplagi. The two battles of Prinitza and Makryplagi thus put an end to Michael Palaiologos's efforts to recover the entirety of the Morea, and secured Latin rule over the Morea for over a generation.

When the former Seljuk Sultan Kaykaus II was arrested in the Byzantine Empire, his younger brother Kayqubad II appealed to Berke. With the assistance of the Kingdom of Bulgaria (Berke's vassal), Nogai invaded the Empire in 1264. By the next year, the Mongol-Bulgarian army was within reach of Constantinople. Nogai forced Michael VIII Palaiologos to release Kaykaus and pay tribute to the Horde. Berke gave Kaykaus Crimea as an appanage and had him marry a Mongol woman. Hulagu died in February 1265 and Berke followed the next year while on campaign in Tiflis, causing his troops to retreat.

The military advantages Michael enjoyed after capturing Constantinople had evaporated by the end of 126, but he would demonstrate his diplomatic skills to successfully recover from these drawbacks. After Settepozzi, Michael VIII dismissed the 60 Genoese galleys that he had hired earlier and began a rapprochement with Venice. Michael secretly negotiated a treaty with the Venetians to grant terms similar to those in the case of Nymphaeum, but Doge Raniero Zeno failed to ratify the agreement. He also signed a treaty in 1263 with the Egyptian Mamluk sultan Baibars and Berke, the Mongol Khan of Kipchak Khanate.

During the reign of Berke there was also a raid against Thrace. In the winter of 1265, the Bulgarian czar, Constantine Tych, requested Mongol intervention against the Byzantines in the Balkans. Nogai Khan led a Mongol raid of 20,000 cavalry (two tumens) against the territories of Byzantine eastern Thrace. In early 1265, Michael VIII Palaeologus confronted the Mongols, but his smaller squadron apparently had very low morale and was quickly routed. Most of them were cut down as they fled. Michael was forced to retreat to Constantinople on a Genoese ship while Nogai's army plundered all of Thrace. Following this defeat, the Byzantine emperor made an alliance with the Golden Horde (which was massively beneficial for the latter), giving his daughter Euphrosyne in marriage to Nogai. Michael also sent much valuable fabric to Golden Horde as tribute.

A Byzantine-Mongol Alliance occurred during the end of the 13th and the beginning of the 14th century between the Byzantine Empire and the Mongol Empire. Byzantium actually tried to maintain friendly relations with both the Golden Horde and the Ilkhanate realms, who were often at war with each other. The alliance involved numerous exchanges of presents, military collaboration and marital links, but dissolved in the middle of the 14th century.

Emperor Michael VIII Palaiologos established an alliance with the Mongols, who themselves were highly favourable to Christianity, as a minority of them were Nestorian Christians. He signed a treaty in 1266 with the Mongol Khan of the Kipchak (the Golden Horde), and he married two of his daughters (conceived through a mistress, a Diplovatatzina) to Mongol kings: Euphrosyne Palaiologina, who married Nogai Khan of the Golden Horde, and Maria Palaiologina, who married Abaqa Khan of Ilkhanid Persia.

The greatest threat to Byzantium was not the Muslims but their Christian counterparts in the West — Michael VIII knew that the Venetians and the Franks would no doubt launch another attempt to establish Latin rule in Constantinople. The situation became worse when Charles I of Anjou conquered Sicily from the Hohenstaufens in 1266. In 1267, Pope Clement IV arranged a pact, whereby Charles would receive land in the East in return for assisting a new military expedition to Constantinople. A delay on Charles' end meant that Michael VIII was given enough time to negotiate a union between the Church of Rome and that of Constantinople in 1274, thus removing papal support for an invasion of Constantinople.

A first treaty was concluded in 1265 but not ratified by Venice. Finally, the rise of Charles of Anjou in Italy and his hegemonic ambitions in the wider region, which threatened both Venice and the Byzantines, provided additional incentive for both powers to seek an accommodation. A new treaty was concluded in April 1268, with terms and wording more favourable to the Byzantines. It provided for a mutual truce of five years, the release of prisoners, and readmitted and regulated the presence of Venetian merchants in the Empire. Many of the trading privileges they had previously enjoyed were restored, but on considerably less advantageous terms to Venice than what Palaiologos had been willing to concede in 1265. The Byzantines were forced to recognize the Venetian possession of Crete and other areas captured after the Fourth Crusade, but succeeded in avoiding a full rupture with Genoa, while removing for a time the threat of a Venetian fleet assisting Charles of Anjou in his plans to capture Constantinople.

In the early 1270s, Michael VIII Palaiologos launched a major campaign against John I Doukas, ruler of Thessaly. It was to be headed by his own brother, the despotes John Palaiologos. To prevent any aid coming to him from the Latin principalities, he also dispatched a fleet of 73 ships, led by Philanthropenos, to harass their coasts. The Byzantine army, however, was defeated at the Battle of Neopatras with the aid of troops from the Duchy of Athens. At the news of this, the Latin lords took heart, and resolved to attack the Byzantine navy, anchored at the port of Demetrias.

The Latin fleet caught the Byzantines by surprise, and their initial attack was so violent that they made good progress. Their ships, on which high wooden towers had been erected, had the advantage, and many Byzantine seamen and soldiers were killed or drowned. Just as victory seemed within the Latins' grasp, however, reinforcements arrived led by the despotes John Palaiologos. While retreating from Neopatras, the despotes had learned of the impending battle. Gathering whatever men he could, he rowed forty miles in one night and reached Demetrias just as the Byzantine fleet was beginning to waver.

His arrival boosted the Byzantines' morale, and Palaiologos's men, ferried on board the ships by small boats, began to replenish their casualties and turn the tide. The battle continued all day, but by nightfall, all but two Latin ships had been captured. The Latin casualties were heavy, and included the triarch of Negroponte Guglielmo II da Verona. Many other nobles were captured, including the Venetian Fillippo Sanudo, who was probably the fleet's overall commander. The victory at Demetrias went a long way to mitigating the disaster of Neopatras for the Byzantines. It also marked the beginning of a sustained offensive across the Aegean

In 1266 or 1268, Michael II of Epirus died, and his possessions were divided among his sons: his eldest legitimate son, Nikephoros, inherited what remained of Epirus proper, while John received Thessaly with his capital at Neopatras. Both brothers were hostile to the restored Byzantine Empire, which aimed to reclaim their territories, and maintained close relations with the Latin states in southern Greece.

Michael launched offensives against the Sicilian holdings in Albania, and against John Doukas in Thessaly. Michael assembled a huge force. This force was sent against Thessaly aided by the Byzantine navy. Doukas was caught completely by surprise by the rapid advance of the imperial forces, and was bottled up with few men in his capital. Doukas requested the aid of John I de la Roche, the Duke of Athens. The Byzantine troops panicked under the sudden attack of the smaller but disciplined Latin force, and broke completely when a Cuman contingent abruptly switched sides. Despite John Palaiologos's attempts to rally his forces, they fled and scattered.

In 1277 in a popular uprising led by Ivailo broke out in north-eastern Bulgaria against the incapability of Emperor Constantine Tikh Asen to cope with the constant Mongol invasions which devastated the country for years. The Byzantine Emperor Michael VIII Palaiologos decided to make use of the instability in Bulgaria. He sent an army to impose his ally Ivan Asen III on the throne. Ivan Asen III gained control of the area between Vidin and Cherven. Ivailo was besieged by the Mongols at Drastar (Silistra) and the nobility in the capital Tarnovo accepted Ivan Asen III for Emperor.

In the same year, however, Ivailo managed to make a breakthrough in Drastar and headed for the capital. In order to help his ally, Michael VIII sent a 10,000-strong army towards Bulgaria under Murin. When Ivailo learned of that campaign he abandoned his march to Tarnovo. Although his troops were outnumbered, the Bulgarian leader attacked Murin in the Kotel Pass on 17 July 1279 and the Byzantines were completely routed. Many of them perished in the battle, while the rest were captured and later killed by orders from Ivailo.

After the defeat Michael VIII sent another army of 5,000 troops under Aprin but it was also defeated by Ivailo before reaching the Balkan Mountains. Without support, Ivan Asen III had to flee to Constantinople. The internal conflict in Bulgaria continued to 1280 when Ivailo had in turn to flee to the Mongols and George I Terter ascended to the throne.

The siege of Berat in Albania by the forces of the Angevin Kingdom of Sicily against the Byzantine garrison of the city took place in 1280–1281. Berat was a strategically important fortress, whose possession would allow the Angevins access to the heartlands of the Byzantine Empire. A Byzantine relief force arrived in spring 1281, and managed to ambush and capture the Angevin commander, Hugo de Sully. Thereupon, the Angevin army panicked and fled, suffering heavy losses in killed and wounded as it was attacked by the Byzantines. This defeat ended the threat of a land invasion of the Byzantine Empire, and along with the Sicilian Vespers marked the end of the Western threat to reconquer Byzantium.

Michael VIII subsidized Peter III of Aragon's attempts to seize Sicily from Charles I of Anjou. Michael's efforts paid off with the outbreak of the Sicilian Vespers, a successful revolt that overthrew the Angevin King of Sicily and installed Peter III of Aragon as King of Sicily in 1281. It broke out on Easter 1282 against the rule of the French-born king Charles I of Anjou, who had ruled the Kingdom of Sicily since 1266. Within six weeks, approximately 13,000 French men and women were slain by the rebels, and the government of Charles lost control of the island. This began the War of the Sicilian Vespers.

The war resulted in the division of the old Kingdom of Sicily; at Caltabellotta, Charles II was confirmed as king of Sicily's peninsular territories, while Frederick III was confirmed as king of the island territories.

Andronikos II Palaiologos's reign was marked by the beginning of the decline of the Byzantine Empire. During his reign, the Turks conquered most of the Western Anatolian territories of the Empire and, during the last years of his reign, he also had to fight his grandson Andronikos in the First Palaiologan Civil War. The civil war ended in Andronikos II's forced abdication in 1328 after which he retired to a monastery, where he spent the last four years of his life.

Andronikos II was plagued by economic difficulties. During his reign the value of the Byzantine hyperpyron depreciated precipitously, while the state treasury accumulated less than one seventh the revenue (in nominal coins) that it had previously. Seeking to increase revenue and reduce expenses, Andronikos II raised taxes, reduced tax exemptions, and dismantled the Byzantine fleet (80 ships) in 1285, thereby making the Empire increasingly dependent on the rival republics of Venice and Genoa. In 1291, he hired 50–60 Genoese ships, but the Byzantine weakness resulting from the lack of a navy became painfully apparent in the two wars with Venice in 1296–1302 and 1306–10. Later, in 1320, he tried to resurrect the navy by constructing 20 galleys, but failed.

Osman Bey, upon the death of Bayhoca, son of his brother Savcı Bey, in the Battle of Mount Armenia, conquered Kulaca Hisar Castle, which is a few leagues away from İnegöl and located on the outskirts of Emirdağ. As a result of a night raid with a force of 300 people, the castle was captured by the Turks. This is the first castle conquest in the history of the Ottoman Empire. Since the Christian people of Kulaca Hisar accepted the rule of Osman Bey, the people there were not harmed.

Michael IX Palaiologos was Byzantine Emperor together with his father Andronikos II Palaiologos from 1294 until his death. Andronikos II and Michael IX ruled as equal co-rulers, both using the title autokrator.

Despite his military prestige, he suffered several defeats, for unclear reasons: his inability as a commander, the deplorable state of the Byzantine army or just simply bad luck. The only Palaiologan emperor to predecease his father, his premature death at age 43 was attributed in part to grief over the accidental murder of his younger son Manuel Palaiologos by retainers of his older son and later co-emperor Andronikos III Palaiologos.

In 1296, the local Genoese residents of Constantinople destroyed the Venetian quarter and killed many Venetian civilians. Despite the Byzantine–Venetian truce of 1285, the Byzantine emperor Andronikos II Palaiologos immediately showed support for his Genoese allies by arresting the Venetian survivors of the massacre, including the Venetian bailo Marco Bembo.

Venice threatened war with the Byzantine Empire, demanding reparations for the affront they suffered. In July 1296, the Venetian fleet stormed the Bosphorus. During the course of the campaign, various Genoese possessions in the Mediterranean and the Black Sea were captured, including the city of Phocaea. Open war between Venice and the Byzantines did not begin until after the Battle of Curzola and the end of the war with Genoa in the 1299 Treaty of Milan, which left Venice free to pursue her war against the Greeks. The Venetian fleet, reinforced by privateers, began to capture various Byzantine islands in the Aegean Sea, many of which had only been conquered by the Byzantines from Latin lords about twenty years before.

The Byzantine government to propose a peace treaty, signed on 4 October 1302. According to its terms, the Venetians returned most of their conquests. The Byzantines also agreed to repay the Venetians for their losses sustained during the massacre of Venetian residents in 1296.

In early spring of 1302, Michael IX made his first campaign against the Ottoman Empire to get a chance to prove himself in battle. Under his command, up to 16,000 soldiers were collected, 10,000 of whom were a detachment of mercenary Alans; the latter, however, performed their duty badly and plundered both the Turkish population and the Greek with equal zeal. The Turks chose the moment and descended from the mountains. Michael IX ordered to prepare for battle, but no one listened to him.

After defeat and a short stay in the fortress of Magnesia, Michael IX retreated to Pergamum and then went to Adramyttium, where he met the New Year of 1303, and by the summer he was in the city of Cyzicus. He still didn't give up his attempts to gather a new army to replace the disintegrated old one and to improve the situation. But by that time the Turks had already seized the area along the lower reaches of the (Sangarius) Sakarya River and defeated another Greek army in the town of Bapheus, near Nicomedia (27 July 1302). It was becoming clear to everyone that the Byzantines had lost the war. 

Osman I had succeeded in the leadership of his clan in c. 1281, and over the next two decades launched a series of ever-deeper raids into the Byzantine borderlands of Bithynia. By 1301, the Ottomans were besieging Nicaea, the former imperial capital, and harassing Prusa. The Turkish raids also threatened the port city of Nicomedia with famine, as they roamed the countryside and prohibited the collection of the harvest.

In the spring of 1302, Emperor Michael IX launched a campaign which reached south to Magnesia. The Turks, awed by his large army, avoided battle. To counter the threat to Nicomedia, Michael's father, Andronikos II Palaiologos, sent a Byzantine force of some 2,000 men (half of whom were recently hired Alan mercenaries), under the megas hetaireiarches, George Mouzalon, to cross over the Bosporus and relieve the city. At the plain of Bapheus, the Byzantines met a Turkish army of some 5,000 light cavalry under Osman himself, composed of his own troops as well as allies from the Turkish tribes of Paphlagonia and the Maeander River area. The Turkish cavalry charged the Byzantines, whose Alan contingent did not participate in the battle. The Turks broke the Byzantine line, forcing Mouzalon to withdraw into Nicomedia under the cover of the Alan force. 

Bapheus was the first major victory for the nascent Ottoman Beylik, and of major significance for its future expansion: the Byzantines effectively lost control of the countryside of Bithynia, withdrawing to their forts, which, isolated, fell one by one. The Byzantine defeat also sparked a mass exodus of the Christian population from the area into the European parts of the empire, further altering the region's demographic balance.

After the failure of the co-emperor Michael IX to stem the Turkish advance in Asia Minor in 1302 and the disastrous Battle of Bapheus, the Byzantine government hired the Catalan Company of Almogavars (adventurers from Catalonia) led by Roger de Flor to clear Byzantine Asia Minor of the enemy. In spite of some successes, the Catalans were unable to secure lasting gains. Being more ruthless and savage than the enemy they intended to subdue they quarreled with Michael IX, and eventually openly turned on their Byzantine employers after the murder of Roger de Flor in 1305; together with a party of willing Turks they devastated Thrace, Macedonia, and Thessaly on their road to Latin occupied southern Greece. There they conquered the Duchy of Athens and Thebes. 

After the battle of Bapheus in 1302, Turkish gazis from all parts of Anatolia began raiding Byzantine territories. Byzantine emperor Andronikos II Palaiologos tried to form an alliance with the Ilkhanid Mongols against the Ottoman threat. Failing to secure frontiers by the alliance he decided to attack the Ottomans with his own army. 

The Anatolian army of the Byzantine Empire was composed of the forces of local garrisons like Adranos, Bidnos, Kestel and Kete. In the spring of 1303, the Byzantine army advanced to Yenişehir, an important Ottoman city north east of Bursa. Osman I defeated them near the pass of Dimbos on the way to Yenişehir. During the battle both sides suffered heavy casualties.

The Battle of the Cyzicus was fought in October 1303 between the Catalan Company of the East under Roger de Flor, acting as mercenaries on behalf of the Byzantine Empire, and the Karasid Turks under Karesi Bey. It was the first of several engagements between the two sides during the Catalan Company's Anatolian Campaign. The result was a crushing Catalan victory. The almogavars of the Catalan Company made a surprise attack on the Oghuz Turkish camp located at the Cape Artake, killing about 3000 cavalry and 10,000 infantry and capturing many women and children.

The 1304 campaign began with a month's delay due to continuous disputes between the almogavars and their Alan allies, which caused 300 deaths in the forces of the latter. Finally, in early May, Roger de Flor began the campaign to raise the siege of Philadelphia with 6,000 almogavars and 1,000 Alans. Philadelphia at that time was suffering from a siege by Yakup bin Ali Şir, governor of the Germiyanids from the powerful emirate of Germiyan-oğhlu. After a few days, the almogavars arrived at the Byzantine city of Achyraus and descended by the valley of the River Kaikos until they arrived at the city of Germe (now known as Soma), a Byzantine fortification that had previously fallen to the Turks. The Turks who were there tried to flee as fast as possible, but their rearguard was attacked by the troops of Roger de Flor in what came to be called the Battle of Germe.

After the victory in Germe, the Company resumed its march, passing through Chliara and Thyatira and entered the valley of the Hermos River. On their way, they stopped in various places, abusing the Byzantine governors for their lack of courage. Roger de Flor even planned to hang some of them; naming the Bulgarian captain Sausi Crisanislao, who finally obtained a pardon.

Upon learning of the imminent arrival of the Great Company, Bey Yakup bin Ali Şir, head of the coalition of the Turkish troops from the emirates of Germiyan-oğhlu and Aydın-oğhlu, decided to lift the siege of Philadelphia and face the Company in a suitable location (Aulax) with his 8,000 cavalry and 12,000 infantry.

Roger de Flor took command of the Company cavalry, dividing it into three contingents (Alans, Catalans and Romans), while Corbarán of Alet did the same with the infantry. The Catalans achieved a great victory over the Turks in what would come to be known as the Battle of Aulax, with only 500 Turkish infantry and 1,000 cavalrymen managing to escape alive. After this battle de Flor made a triumphant entrance into Philadelphia, being received by its magistrates and the bishop Teolepto.

Having already accomplished the principal mission entrusted to him by the emperor, Roger de Flor decided to consolidate the defence of Philadelphia by conquering the nearby fortresses which had fallen into the hands of the Turks. Thus, the almogavars marched north towards the fortress of Kula, forcing the Turks who were there to flee. The Greek garrison of Kula received de Flor as a liberator, but he, not appreciating how a seemingly impregnable fortress could be allowed to fall into the hands of the Turks without a battle, beheaded the governor and condemned the commander to the gallows. The same harshness was applied when, days later, the almogavars took the fortification of Furnes, located further north. After that, de Flor returned with his troops to Philadelphia to claim payment for his successful campaign.

During 1303–1304 Tsar Theodore Svetoslav of Bulgaria invaded Eastern Thrace. He sought revenge for the Tatar attacks on the state in the previous 20 years. The traitors were punished first, including Patriarch Joachim III, who was found guilty of helping the enemies of the crown. Then the tsar turned to Byzantium, which had inspired the Tatar invasions and had managed to conquer many Bulgarian fortresses in Thrace. In 1303, his army marched southwards and regained many towns. In the following year the Byzantines counter-attacked and the two armies met near the Skafida river. Michael IX at this time was engaged in a war with the rebellious Catalan Company, whose leader, Roger de Flor, refused to fight the Bulgarians if Michael IX and his father didn't pay him the agreed sum of money. 

At the beginning of the battle, Michael IX, who fought bravely in the forefront, had an advantage over the enemy. He forced the Bulgarians to retreat along the road to Apolonia, but he was unable to keep his own soldiers heated up in pursuit. Between the Byzantines and the fleeing Bulgarians, there was the deep and very turbulent Skafida river, with the only bridge across which was damaged by the Bulgarians before the battle. When the Byzantine soldiers in a large crowd tried to cross the bridge, it collapsed. Many of the soldiers drowned, the rest began to panic. At that moment, the Bulgarians returned to the bridge and decided the outcome of the battle, snatching victory from the enemies.

After two years of victorious campaigns against the Turks the indiscipline and the character of a foreign army in the heart of the Empire were seen as a growing danger, and on April 30 1305 the emperor's son (Michael IX Palaiologos) ordered mercenary Alans to murder Roger de Flor and exterminate the Company in Adrianople while they attended a banquet organised by the Emperor. About 100 cavalry men and 1,000 infantrymen perished.

After the murder of de Flor the local Byzantine population rose up against the Catalans in Constantinople and killed many of them, including at the main barracks. Prince Michael ensured that as many as possible were killed before news reached the main force in Gallipoli. Some however escaped and carried the news of the massacre to Gallipoli after which the Catalans went on a killing spree of their own, killing all the local Byzantines. 

The Battle of Apros occurred between the forces of the Byzantine Empire, under co-emperor Michael IX Palaiologos, and the forces of the Catalan Company, at Apros on July 1305. The Catalan Company had been hired by the Byzantines as mercenaries against the Turks, but despite the Catalans' successes against the Turks, the two allies distrusted each other, and their relationship was strained by the Catalans' financial demands. Eventually, Emperor Andronikos II Palaiologos and his son and co-ruler Michael IX had the Catalan leader, Roger de Flor, assassinated with his entourage in April 1305.

In July, the Byzantine army, comprising a large contingent of Alans as well as many Turcopoles, confronted the Catalans and their own Turkish allies near Apros in Thrace. Despite the Imperial Army's numerical superiority, the Alans withdrew after the first charge, whereupon the Turcopoles deserted en block to the Catalans. Prince Michael was injured and left the field and the Catalans won the day. The Catalans proceeded to ravage Thrace for two years, before moving west and south through Thessaly, to conquer the Latin Duchy of Athens in 1311.

Following the Fall of Acre in 1291, the Order had moved its base to Limassol in Cyprus. Their position in Cyprus was precarious; their limited income made them dependent on donations from Western Europe and involved them in quarrels with King Henry II of Cyprus, while the loss of Acre and the Holy Land led to widespread questioning on the purpose of the monastic orders, and proposals to confiscate their possessions. According to Gérard de Monréal, as soon as he was elected as Grand Master of the Knights Hospitaller in 1305, Foulques de Villaret planned the conquest of Rhodes, which would ensure him a liberty of action that he could not have as long as the Order remained on Cyprus, and would provide a new base for war against the Turks.

Rhodes was an attractive target: a fertile island, it was strategically located off the southwestern coast of Asia Minor, astride the trade routes to either Constantinople or Alexandria and the Levant. The island was a Byzantine possession, but the increasingly feeble Empire was evidently unable to protect its insular possessions, as demonstrated by the seizure of Chios in 1304 by the Genoese Benedetto Zaccaria, who secured recognition of his possession from Emperor Andronikos II Palaiologos (r. 1282–1328), and the competing activities of the Genoese and Venetians in the area of the Dodecanese. 

The Hospitaller conquest of Rhodes took place in 1306–1310. The Knights Hospitaller, led by Grand Master Foulques de Villaret, landed on the island in summer 1306 and quickly conquered most of it except for the city of Rhodes, which remained in Byzantine hands. Emperor Andronikos II Palaiologos sent reinforcements, which allowed the city to repel the initial Hospitaller attacks, and persevere until it was captured on 15 August 1310. The Hospitallers transferred their base to the island, which became the centre of their activities until it was conquered by the Ottoman Empire in 1522.

The Battle of Halmyros, known by earlier scholars as the Battle of the Cephissus or Battle of Orchomenos, was fought on 15 March 1311, between the forces of the Frankish Duchy of Athens and its vassals under Walter of Brienne against the mercenaries of the Catalan Company, resulting in a decisive victory for the mercenaries.

The battle was a decisive event in the history of Frankish Greece; almost the entire Frankish elite of Athens and its vassal states lay dead on the field or in captivity, and when the Catalans moved onto the lands of the Duchy, there was scant resistance. The Greek inhabitants of Livadeia immediately surrendered their strongly fortified town, for which they were rewarded with the rights of Frankish citizens. Thebes, the capital of the Duchy, was abandoned by many of its inhabitants, who fled to the Venetian stronghold of Negroponte, and was plundered by the Catalan troops. Finally, Athens was surrendered to the victors by Walter's widow, Joanna of Châtillon. All of Attica and Boeotia passed peacefully into the hands of the Catalans. The Catalans divided the territory of the Duchy among themselves. The decimation of the previous feudal aristocracy allowed the Catalans to take possession relatively easily, in many cases marrying the widows and mothers of the very men they had slain in Halmyros. The Catalans' Turkish allies, however, refused the offer to settle in the Duchy. The Turks of Halil took their share of the booty and headed for Asia Minor, only to be attacked and almost annihilated by a joint Byzantine and Genoese force as they tried to cross the Dardanelles a few months later.

Öz Beg, whose total army exceeded 300,000, repeatedly raided Thrace in aid of Bulgaria's war against Byzantium and Serbia beginning in 1319. The Byzantine Empire under Andronikos II Palaiologos and Andronikos III Palaiologos was raided by the Golden Horde between 1320 and 1341, until the Byzantine port of Vicina Macaria was occupied. Friendly relations were established with the Byzantine Empire for a brief period after Öz Beg married Andronikos III Palaiologos's illegitimate daughter, who came to be known as Bayalun. In 1333, she was given permission to visit her father in Constantinople and never returned, apparently fearing her forced conversion to Islam. Öz Beg's armies pillaged Thrace for forty days in 1324 and for 15 days in 1337, taking 300,000 captives. In 1330, Öz Beg sent 15,000 troops to Serbia in 1330 but was defeated. Backed by Öz Beg, Basarab I of Wallachia declared an independent state from the Hungarian crown in 1330.

The Byzantine civil war of 1321–1328 was a series of conflicts fought in the 1320s between the Byzantine emperor Andronikos II Palaiologos and his grandson Andronikos III Palaiologos over control of the Byzantine Empire.

The Siege of Bursa occurred from 1317 until the capture on 6 April 1326, when the Ottomans deployed a bold plan to seize Prusa (modern-day Bursa, Turkey). The Ottomans had not captured a city before; the lack of expertise and adequate siege equipment at this stage of the war meant that the city fell only after six or nine years. After the fall of the city, his son and successor Orhan made Bursa the first official Ottoman capital and it remained so until 1366, when Edirne became the new capital.

Andronikos III Palaiologos's reign included the last failed attempts to hold back the Ottoman Turks in Bithynia and the defeat at Rusokastro against the Bulgarians, but also the successful recovery of Chios, Lesbos, Phocaea, Thessaly, and Epirus. His early death left a power vacuum that resulted in the disastrous civil war between his widow, Anna of Savoy, and his closest friend and supporter, John VI Kantakouzenos, leading to the establishment of the Serbian Empire.

By the accession of Andronicus in 1328, the Imperial territories in Anatolia had dramatically shrunk from almost all of the west of modern Turkey forty years earlier to a few scattered outposts along the Aegean Sea and a small core province around Nicomedia within about 150 km of the capital city Constantinople. Recently the Ottoman Turks had captured the important city of Prusa (Bursa) in Bithynia. Andronicus decided to relieve the important besieged cities of Nicomedia and Nicaea, and hoped to restore the frontier to a stable position.

Andronicus led an army of about 4,000 men, which was the greatest he could muster. They marched along the Sea of Marmara towards Nicomedia. At Pelekanon, a Turkish army led by Orhan I had encamped on the hills to gain a strategic advantage and blocked the road to Nicomedia. On 10 June, Orhan sent 300 cavalry archers downhill to lure the Byzantines unto the hills, but these were driven off by the Byzantines, who were unwilling to advance further. The belligerent armies engaged in indecisive clashes until nightfall. The Byzantine army prepared to retreat, but the Turks gave them no chance. Both Andronicus and Cantacuzene were lightly wounded, while rumors spread that the Emperor had either been killed or mortally wounded, resulting in panic. Eventually the retreat turned into a rout with heavy casualties on the Byzantine side. Cantacuzene led the remaining Byzantine soldiers back to Constantinople by sea.

In 1328, the rise of a new and energetic emperor, Andronikos III Palaiologos, to the Byzantine throne, marked a turning-point in relations. One of the leading Chian nobles, Leo Kalothetos, went to meet the new emperor and his chief minister, John Kantakouzenos, to propose a reconquest of the island. Andronikos III readily agreed. In autumn 1329 Andronikos III assembled a fleet of 105 vessels—including the forces of the Latin Duke of Naxos, Nicholas I Sanudo—and sailed to Chios.

Even after the imperial fleet reached the island, Andronikos III offered to let Martino keep his possessions in exchange for the installation of a Byzantine garrison and the payment of an annual tribute, but Martino refused. He sank his three galleys in the harbour, forbade the Greek population to bear arms and locked himself with 800 men in his citadel, where he raised his own banner instead of the emperor's. His will to resist was broken, however, when Benedetto surrendered his own fort to the Byzantines, and when he saw the locals welcoming them, he was soon forced to surrender. 

Following the recapture of Constantinople from the Latins, the Byzantines concentrated their efforts on restoring their hold on Greece. Troops had to be taken from the eastern front in Anatolia and into the Peloponnese, with the disastrous consequence that what land the Nicaean Empire held in Anatolia was now open to Ottoman raids. With the increasing frequency and ferocity of raids, Byzantine imperial authorities pulled back from Anatolia.

By 1326, lands around Nicaea had fallen into the hands of Osman I. He had also captured the city of Bursa, establishing a capital dangerously close to the Byzantine capital of Constantinople. In 1328, Orhan, Osman's son, began the siege of Nicaea, which had been in a state of intermittent blockade since 1301. The Ottomans lacked the ability to control access to the town through the lakeside harbour. As a result, the siege dragged on for several years without conclusion.

In 1329, Emperor Andronicus III attempted to break the siege. He led a relief force to drive the Ottomans away from both Nicomedia and Nicaea. After some minor successes, however, the force suffered a reverse at Pelekanon and withdrew. When it was clear that no effective Imperial force would be able to restore the frontier and drive off the Ottomans, the city proper fell in 1331.

The Holy League was a military alliance of the chief Christian states of the Aegean Sea and the Eastern Mediterranean against the mounting threat of naval raids by the Turkish beyliks of Anatolia. The alliance was spearheaded by the main regional naval power, the Republic of Venice, and included the Knights Hospitaller, the Kingdom of Cyprus, and the Byzantine Empire, while other states also promised support. After a notable success in the Battle of Adramyttion, the Turkish naval threat receded for a while; coupled with the diverging interests of its members, the league atrophied and ended in 1336/7.

To overcome his failure to secure gains against the Serbians, Andronikos III attempted to annex Bulgarian Thrace, but the new tsar Ivan Alexander of Bulgaria defeated Byzantine forces at Battle of Rusokastro on 18 July 1332. In the summer of the same year, the Byzantines gathered an army and without a declaration of war advanced towards Bulgaria, looting and plundering the villages on their way. The Byzantines seized several castles because Ivan Alexander's attention was focused towards fighting the rebellion of his uncle Belaur in Vidin. He tried to negotiate with the enemy without success. The Emperor decided to act swiftly during the course of five days, when his cavalry covered 230 km to reach Aitos and face the invaders.

The battle began at six in the morning and continued for three hours. The Byzantines tried to prevent the Bulgarian cavalry from surrounding them, but their manoeuvre failed. The cavalry moved around the first Byzantine line, leaving it for the infantry and charged the rear of their flanks. After a fierce fight the Byzantines were defeated, abandoned the battlefield and took refuge in Rusokastro.

Öljaitü's son, the last Ilkhan Abu Sa'id Bahadur Khan, was enthroned in 1316. He was faced with rebellion in 1318 by the Chagatayids and Qara'unas in Khorasan, and an invasion by the Golden Horde at the same time. An Anatolian emir, Irenchin, also rebelled. Irenchin was crushed by Chupan of the Taichiud in the Battle of Zanjan-Rud on 13 July 1319. Under the influence of Chupan, the Ilkhanate made peace with the Chagatais, who helped them crush the Chagatayid revolt, and the Mamluks. In 1327, Abu-Sai'd replaced Chupan with "Big" Hasan. Hasan was accused of attempting to assassinate the khan and exiled to Anatolia in 1332. The non-Mongol emirs Sharaf-ud-Din Mahmud-Shah and Ghiyas-ud-Din Muhammad were given unprecedented military authority, which irked the Mongol emirs. In the 1330s, outbreaks of the Black Death ravaged the Ilkhanate and both Abu-Sai'd and his sons were killed by 1335 by the plague. Ghiyas-ud-Din put a descendant of Ariq Böke, Arpa Ke'un, on the throne, triggering a succession of short-lived khans until "Little" Hasan took Azerbaijan in 1338. In 1357, Jani Beg of the Golden Horde conquered Chupanid-held Tabriz for a year, putting an end to the Ilkhanate remnant.

In 1337 the new Emperor, Andronikos III Palaiologos, took advantage of a secession crisis and arrived in northern Epirus with an army partly composed of 2,000 Turks contributed by his ally Umur of Aydın. Andronikos first dealt with unrest due to attacks by Albanians and then turned his interest to the Despotate. Anna tried to negotiate and obtain the Despotate for her son when he came of age, but Andronikos demanded the complete surrender of the Despotate to which she finally agreed. Thus Epirus came peacefully under imperial rule, with Theodore Synadenos as governor.

The Byzantine civil war of 1341–1347, sometimes referred to as the Second Palaiologan Civil War, was a conflict that broke out in the Byzantine Empire after the death of Andronikos III Palaiologos over the guardianship of his nine-year-old son and heir, John V Palaiologos. It pitted on the one hand Andronikos III's chief minister, John VI Kantakouzenos, and on the other a regency headed by the Empress-Dowager Anna of Savoy, the Patriarch of Constantinople John XIV Kalekas, and the megas doux Alexios Apokaukos. The war polarized Byzantine society along class lines, with the aristocracy backing Kantakouzenos and the lower and middle classes supporting the regency. To a lesser extent, the conflict acquired religious overtones; Byzantium was embroiled in the Hesychast controversy, and adherence to the mystical doctrine of Hesychasm was often equated with support for Kantakouzenos.

John V Palaiologos or Palaeologus was Byzantine emperor from 1341 to 1391. His long reign was marked by the gradual dissolution of imperial power amid numerous civil wars and the continuing ascendancy of the Ottoman Turks.

John VI Kantakouzenos was a Greek nobleman, statesman, and general. He served as grand domestic under Andronikos III Palaiologos and regent for John V Palaiologos before reigning as Byzantine emperor in his own right from 1347 to 1354. Deposed by his former ward, he was forced to retire to a monastery under the name Joasaph Christodoulos and spent the remainder of his life as a monk and historian. At age 90 or 91 at his death, he was the longest-lived of the Roman emperors. During John's reign, the empire—already fragmented, impoverished, and weakened—continued to be assailed on every side.

Plague was reportedly first introduced to Europe via Genoese traders from their port city of Kaffa in the Crimea in 1347. During a protracted siege of the city, in 1345–1346 the Mongol Golden Horde army of Jani Beg, whose mainly Tatar troops were suffering from the disease, catapulted infected corpses over the city walls of Kaffa to infect the inhabitants, though it is more likely that infected rats travelled across the siege lines to spread the epidemic to the inhabitants. As the disease took hold, Genoese traders fled across the Black Sea to Constantinople, where the disease first arrived in Europe in summer 1347.

The epidemic there killed the 13-year-old son of the Byzantine emperor, John VI Kantakouzenos, who wrote a description of the disease modelled on Thucydides's account of the 5th century BCE Plague of Athens, but noting the spread of the Black Death by ship between maritime cities. Nicephorus Gregoras also described in writing to Demetrios Kydones the rising death toll, the futility of medicine, and the panic of the citizens. The first outbreak in Constantinople lasted a year, but the disease recurred ten times before 1400.

The Byzantine–Genoese War of 1348–1349 was fought over control over custom dues through the Bosphorus. The Byzantines attempted to break their dependence for food and maritime commerce on the Genoese merchants of Galata, and also to rebuild their own naval power. Their newly constructed navy however was captured by the Genoese, and a peace agreement was concluded.

The failure of the Byzantines to expel the Genoese from Galata meant that they could never restore their sea power, and would thenceforth be dependent either on Genoa or Venice for naval aid. From 1350, the Byzantines allied themselves to the Republic of Venice, which was also at war with Genoa. However, as Galata remained defiant, the Byzantines were forced to settle the conflict in a compromise peace in May 1352.

The Byzantine civil war of 1352–1357 marks the continuation and conclusion of a previous conflict that lasted from 1341 to 1347. It involved John V Palaiologos against the two Kantakouzenoi, John VI Kantakouzenos and his eldest son Matthew Kantakouzenos. John V emerged victorious as the sole emperor of the Byzantine Empire, but the resumption of civil war completed the destruction of the previous conflict, leaving the Byzantine state in ruins.

In the Byzantine civil war which began in 1352, John Palaiologos obtained the help of Serbia, while John Kantakouzenos sought help from Orhan I, the Ottoman bey. Kantakouzenos marched into Thrace to rescue his son, Matthew, who was attacked by Palaiologos shortly after being given this appanage and then refusing to recognize John Palaiologos as heir to the throne.

The Ottoman troops retook some cities that had surrendered to John Palaiologos, and Kantakouzenos allowed the troops to plunder the cities, including Adrianople, thus it seemed that Kantakouzenos was defeating John Palaiologos, who now retreated to Serbia. Emperor Stefan Dušan sent Palaiologos a cavalry force of 4,000 or 6,000 under the command of Gradislav Borilović while Orhan I provided Kantakouzenos 10,000 horsemen. Also Bulgarian tsar Ivan Alexander send unknown number of troops to support Palaiologos and Dušan. The two armies met at an open-field battle near Demotika (modern Didymoteicho) in October 1352, which would decide the fate of the Byzantine Empire, without the direct involvement of the Byzantines. The more numerous Ottomans defeated the Serbs, and Kantakouzenos retained the power, while Palaiologos fled to Venetian Tenedos. According to Kantakouzenos about 7,000 Serbs fell at the battle (deemed exaggerated), while Nikephoros Gregoras (1295–1360) gave the number as 4,000. The battle was the first major battle of the Ottomans on European soil, and it made Stefan Dušan realize the major threat of the Ottomans to Eastern Europe.

On 2 March 1354, the area was struck by an earthquake that destroyed hundreds of villages and towns in the area. Nearly every building in Gallipoli was destroyed, causing the Greek inhabitants to evacuate the city. Within a month, Süleyman Pasha seized the site, quickly fortifying it and populating it with Turkish families brought over from Anatolia.

The Byzantine civil war of 1373–1379 was a military conflict fought in the Byzantine Empire between Byzantine Emperor John V Palaiologos and his son, Andronikos IV Palaiologos, also growing into an Ottoman civil war as well, when Savcı Bey, the son of Ottoman Emperor Murad I joined Andronikos in a joint rebellion against their fathers. It began when Andronikos sought to overthrow his father in 1373. Although he failed, with Genoese aid, Andronikos was eventually able to overthrow and imprison John V in 1376. In 1379 however, John V escaped, and with Ottoman help, regained his throne. The civil war further weakened the declining Byzantine Empire, which had already suffered several devastating civil wars earlier in the century. The major beneficiary of the war were the Ottomans, whose vassals the Byzantines had effectively become.

Manuel II was the author of numerous works of varied character, including letters, poems, a Saint's Life, treatises on theology and rhetoric, and an epitaph for his brother Theodore I Palaiologos and a mirror of princes for his son and heir John. This mirror of princes has special value, because it is the last sample of this literary genre bequeathed to us by Byzantines.

Shortly before his death he was tonsured a monk and received the name Matthew. His wife Helena Dragaš saw to it that their sons, John VIII Palaiologos and Constantine XI Palaiologos, became emperors.

The siege of Constantinople in 1394–1402 was a long blockade of the capital of the Byzantine Empire by the Ottoman Sultan Bayezid I. Already in 1391, the rapid Ottoman conquests in the Balkans had cut off the city from its hinterland. After constructing the fortress of Anadoluhisarı to control the Bosporus strait, from 1394 on, Bayezid tried to starve the city into submission by blockading it both by land and, less effectively, by sea.

The Crusade of Nicopolis was launched to relieve the city, but it was decisively defeated by the Ottomans. In 1399, a French expeditionary force under Marshal de Boucicaut arrived, but was unable to achieve much. The situation became so dire that in December 1399 the Byzantine emperor, Manuel II Palaiologos, left the city to tour the courts of Western Europe in a desperate attempt to secure military aid. The emperor was welcomed with honours, but secured no definite pledges of support. Constantinople was saved when Bayezid had to confront the invasion of Timur in 1402. Bayezid's defeat in the Battle of Ankara in 1402, and the Ottoman civil war that followed, even allowed the Byzantines to regain some lost territories, in the Treaty of Gallipoli.

The Battle of Nicopolis took place on 25 September 1396 and resulted in the rout of an allied crusader army of Hungarian, Croatian, Bulgarian, Wallachian, French, Burgundian, German, and assorted troops (assisted by the Venetian navy) at the hands of an Ottoman force, raising the siege of the Danubian fortress of Nicopolis and leading to the end of the Second Bulgarian Empire. It is often referred to as the Crusade of Nicopolis as it was one of the last large-scale Crusades of the Middle Ages, together with the Crusade of Varna in 1443–1444.

On 10 December 1399, Manuel II sailed to the Morea, where he left his wife and children with his brother Theodore I Palaiologos to be protected from his nephew's intentions. He later landed in Venice in April 1400, then he went to Padua, Vicenza and Pavia, until he reached Milan, where he met Duke Gian Galeazzo Visconti, and his close friend Manuel Chrysoloras. Afterwards, he met Charles VI of France at Charenton on 3 June 1400. During his stay in France, Manuel II continued to contact European monarchs.

In December 1400, he embarked to England to meet Henry IV of England who received him at Blackheath on the 21st of that month,making him the only Byzantine emperor ever to visit England, where he stayed at Eltham Palace until mid-February 1401, and a joust took place in his honour. In addition, he received £2,000, in which he acknowledged receipt of the funds in a Latin document and sealed it with his own golden bull.

The Battle of Ankara or Angora was fought on 20 July 1402 at the Çubuk plain near Ankara, between the forces of the Ottoman Sultan Bayezid I and the Emir of the Timurid Empire, Timur. The battle was a major victory for Timur, and it led to the Ottoman Interregnum. The Byzantines would benefit from this brief respite.

The first full-scale Ottoman siege of Constantinople took place in 1422 as a result of the Byzantine Emperor Manuel II's attempts to interfere in the succession of Ottoman Sultans, after the death of Mehmed I in 1421. This policy of the Byzantines was often used successfully in weakening their neighbours.

When Murad II emerged as the winning successor to his father, he marched into Byzantine territory. The Turks had acquired their own cannon for the first time by the siege of 1422, "falcons", which were short but wide cannons. The two sides were evenly matched technologically, and the Turks had to build barricades "in order to receive ... the stones of the bombards".

John VIII Palaiologos or Palaeologus was the penultimate Byzantine emperor, ruling from 1425 to 1448. In June 1422, John VIII Palaiologos supervised the defense of Constantinople during a siege by Murad II, but had to accept the loss of Thessalonica, which his brother Andronikos had given to Venice in 1423. To secure protection against the Ottomans, he made two journeys to Italy in 1423 and 1439. In 1423 he became the last Byzantine emperor (the first since emperor Constans II' visit in 663) to make a visit to Rome. During the second journey he visited Pope Eugene IV in Ferrara and consented to the union of the Greek and Roman churches. The Union was ratified at the Council of Florence in 1439, which John attended with 700 followers including Patriarch Joseph II of Constantinople and George Gemistos Plethon, a Neoplatonist philosopher influential among the academics of Italy. 

The Crusade of Varna was an unsuccessful military campaign mounted by several European leaders to check the expansion of the Ottoman Empire into Central Europe, specifically the Balkans between 1443 and 1444. It was called by Pope Eugene IV on 1 January 1443 and led by King Władysław III of Poland, John Hunyadi, Voivode of Transylvania, and Duke Philip the Good of Burgundy. The Crusade of Varna culminated in a decisive Ottoman victory over the crusader alliance at the Battle of Varna on 10 November 1444, during which Władysław and the expedition's Papal legate Julian Cesarini were killed.

Constantine XI Dragases Palaiologos was the last Byzantine emperor, reigning from 1449 until his death in battle at the Fall of Constantinople in 1453. Constantine's death marked the end of the Byzantine Empire, which traced its origin to Constantine the Great's foundation of Constantinople as the Roman Empire's new capital in 330. Given that the Byzantine Empire was the Roman Empire's medieval continuation, with its citizens continuing to refer to themselves as Romans, Constantine XI's death and Constantinople's fall also marked the definitive end of the Roman Empire, founded by Augustus almost 1,500 years earlier. Constantine was the last Christian ruler of Constantinople, which alongside his bravery at the city's fall cemented him as a near-legendary figure in later histories and Greek folklore. 

The migration waves of Byzantine Greek scholars and émigrés in the period following the end of the Byzantine Empire in 1453, is considered by many scholars key to the revival of Greek studies that led to the development of the Renaissance humanism and science. These émigrés brought to Western Europe the relatively well-preserved remnants and accumulated knowledge of their own (Greek) civilization, which had mostly not survived the Early Middle Ages in the West. The Encyclopædia Britannica claims: "Many modern scholars also agree that the exodus of Greeks to Italy as a result of this event marked the end of the Middle Ages and the beginning of the Renaissance", although few scholars date the start of the Italian Renaissance this late.

The Fall of Constantinople was the capture of the capital of the Byzantine Empire by the Ottoman Empire. The city fell on 29 May 1453, the culmination of a 53-day siege which had begun on 6 April 1453. The attacking Ottoman Army, which significantly outnumbered Constantinople's defenders, was commanded by the 21-year-old Sultan Mehmed II (later called "Mehmed the Conqueror"), while the Byzantine army was led by Emperor Constantine XI Palaiologos. After conquering the city, Mehmed II made Constantinople the new Ottoman capital, replacing Adrianople.

The conquest of Constantinople and the fall of the Byzantine Empire was a watershed of the Late Middle Ages and is considered the end of the medieval period. The city's fall also stood as a turning point in military history. Since ancient times, cities and castles had depended upon ramparts and walls to repel invaders. The Walls of Constantinople, especially the Theodosian Walls, were some of the most advanced defensive systems in the world. These fortifications were overcome with the use of gunpowder, specifically in the form of large cannons and bombards, heralding a change in siege warfare.

As the only stable long-term state in Europe during the Middle Ages, Byzantium isolated Western Europe from newly emerging forces to the East. Constantly under attack, it distanced Western Europe from Persians, Arabs, Seljuk Turks, and for a time, the Ottomans. From a different perspective, since the 7th century, the evolution and constant reshaping of the Byzantine state were directly related to the respective progress of Islam.

Some scholars focused on the positive aspects of Byzantine culture and legacy, French historian Charles Diehl described the Byzantine Empire by saying:

Byzantium created a brilliant culture, may be, the most brilliant during the whole Middle Ages, doubtlessly the only one existing in Christian Europe before the XI century. For many years, Constantinople remained the sole grand city of Christian Europe ranking second to none in splendour. Byzantium literature and art exerted a significant impact on peoples around it. The monuments and majestic works of art, remaining after it, show us the whole lustre of byzantine culture. That's why Byzantium held a significant place in the history of Middle Ages and, one must admit it, a merited one.