Mehmed II: From Boy Sultan to Conqueror of Constantinople

The entry of Sultan Mehmed II into Constantinople, painting by Fausto Zonaro (1854–1929)

The Fall of Constantinople (1453)

Constantinople, the ancient Byzantine capital, was the ultimate prize for Mehmed II – a city of immense symbolic and strategic importance. By the time Mehmed regained the throne, this once-majestic metropolis had been reduced to a beleaguered enclave surrounded by Ottoman lands. Yet it still tantalised as the “Red Apple” of Ottoman ambition. Immediately upon his accession in 1451, the 19-year-old sultan prepared in earnest for a final assault on the city that had defied Muslim armies for over 700 years. Mehmed understood that taking Constantinople would secure his legacy as a great conqueror in the eyes of both his contemporaries and posterity.

The young sultan’s preparations were meticulous and bold. First, Mehmed moved to dominate the Bosphorus Strait, the narrow waterway linking the Black Sea to the Sea of Marmara and Constantinople’s harbour. On the Asian side of the strait stood Anadoluhisarı, a fortress built decades earlier by an Ottoman predecessor. Mehmed set out to build an even larger stronghold on the European shore, directly across from the older fortress. Working at remarkable speed, his crews erected the massive Rumelihisarı (Fortress of Rumeli) in 1452, its thick walls and three tall towers looming over the strait’s narrowest point. This new castle, built within sight of Constantinople’s walls, gave Mehmed a stranglehold on sea traffic. By installing heavy cannon there, the sultan could levy tolls on any ships attempting to reach or leave the Byzantine capital. Famously, when a Venetian vessel tried to run the gauntlet without permission, Mehmed’s gunners shot it to splinters with a single enormous cannonball. The surviving sailors were fished out of the water and executed on Mehmed’s orders – a stark message that the Bosphorus was now under Ottoman control.

Over the winter of 1452–53, preparations intensified. In Edirne, Mehmed had hired a talented Hungarian cannon-founder named Orban, who cast for him one of the largest bombard cannons ever seen in Europe. This colossal gun, nicknamed “the Basilica,” could fire stone balls weighing hundreds of pounds – ideal for smashing medieval fortifications. Mehmed assembled an artillery train of dozens of cannons (unusual and cutting-edge weapons at that time), and he strengthened the Ottoman navy to blockade Constantinople from the sea. By the spring of 1453, an Ottoman army, perhaps 80,000 to 100,000 strong, marched to surround Constantinople, accompanied by elite Janissary infantry, cavalry from across the realm, and siege engineers. Across the Golden Horn inlet, a fleet of some 300 Ottoman ships – mostly transports and galleys – moved in to seal off the city’s harbour. Constantinople, led by the last Byzantine Emperor Constantine XI Palaiologos, was now alone, nearly encircled and outnumbered. Its formidable triple land walls were its final hope.

In early April 1453, the Siege of Constantinople began in earnest. Mehmed established his headquarters in a grand field tent before the Walls of Theodosius, and Ottoman cannons roared to life. The sultan’s artillery battered the ancient walls day after day, the thunder of cannon fire echoing across the Bosphorus. Massive stone cannonballs cracked masonry and shook the defenders’ resolve, but the Byzantines tenaciously repaired breaches each night. Mehmed’s forces attempted several frontal assaults only to be repelled by the desperate defenders. Frustrated by the stalemate on land, Mehmed conceived an audacious plan to bypass the infamous defensive chain that barred his navy from the Golden Horn harbour. On the night of April 22, in a remarkable feat of military engineering, the Ottomans hauled dozens of ships overland on greased wooden tracks, skirting around the Genoese colony of Galata and launching them into the calm waters of the Golden Horn – behind the enemy chain. Constantinople’s defenders awoke to find an Ottoman flotilla suddenly menacing the city’s once-secure northern sea walls. The Byzantines were forced to stretch their dwindling troops even thinner.

For weeks, the siege ground on, with mounting desperation on both sides. By late May, after nearly fifty-seven days under siege, Constantinople was exhausted. Food and supplies were nearly gone, and no relief army was coming. Sultan Mehmed sensed victory was at hand. In the pre-dawn hours of May 29, 1453, he ordered a final all-out assault. Waves of Ottoman troops surged against the walls. After fierce fighting, a detachment of Janissaries breached a section of the inner wall at the Gate of St. Romanus, where a cannon shot had opened a critical gap. The defence finally crumbled. Ottoman soldiers poured into the city as dawn broke, and Constantinople – capital of the Eastern Roman (Byzantine) Empire for over a millennium – fell to Mehmed II. Emperor Constantine XI died in the fighting, reputedly throwing off his imperial regalia and charging into the fray to die anonymously alongside his soldiers.

When the dust settled, Sultan Mehmed II entered the conquered city in triumph. Yet what he found was a haunting scene of ruins and silence. Many of Constantinople’s grand churches and palaces had been damaged or abandoned after years of decline and the final onslaught. According to later accounts, Mehmed wandered through the great Palace of the Emperors – now an empty shell with birds nesting in its crumbling halls – and poignantly recited lines from the Persian poet Saadi:

“The spider is curtain-bearer in the palace of Chosroes;
The owl sounds the relief in the castle of Afrasiyab.”

These poetic words, uttered amid the ruins, capture Mehmed’s reflective mood. They speak of the transience of worldly glory: even the mighty palaces of legendary kings (Chosroes of Persia, Afrasiyab of Turan) had become homes only to spiders and owls. Mehmed II, at age 21, was now the master of Constantinople, but he understood on some level that he was walking through history’s graveyard – the fallen Byzantines had simply been the latest to succumb to time and conquest.

Mehmed moved swiftly to make the city his own. He famously rode to the Hagia Sophia, the great cathedral of Eastern Christendom, and ordered it converted into a royal mosque. He granted his soldiers three days to plunder – a customary reward in medieval warfare – but then quickly restored order to prevent the total destruction of his prize. Impressed by the city’s majesty and strategic position, Mehmed declared Constantinople the new capital of his Ottoman Empire (replacing Edirne). He took the title “Kayser-i Rûm” (Caesar of Rome), positioning himself as the legitimate heir of the Eastern Roman emperors by right of conquest. Though Western Europe’s Catholic powers refused to acknowledge any Ottoman claim to Roman legacy, Mehmed’s gesture had deep significance. He saw himself not just as sultan of a Turkish state, but as the rightful world-emperor in the Roman tradition. To reinforce this position, Mehmed sought the support of the Eastern Orthodox Church, which had survived the conquest. He appointed the scholar-monk Gennadius Scholarius as the new Patriarch of Constantinople, granting him authority over Orthodox Christians in Ottoman lands. In return, Patriarch Gennadius II recognised Mehmed II as the protector of Orthodoxy and successor to the Byzantine emperors in a civic sense. This savvy move helped pacify the city’s Greek population and gave Mehmed a veneer of legitimacy as more than a foreign conqueror.

The conquest of Constantinople sent shockwaves around the world. In Europe, church bells tolled in mourning – medieval Christendom regarded the city’s fall as a nearly apocalyptic event. In the Islamic world, by contrast, celebrations erupted. A oft-cited hadith (saying) attributed to Prophet Muhammad had prophesied that “Surely, Constantinople shall be conquered: what a wonderful leader will her conqueror be, and what a wonderful army will that army be!” Many Muslims saw Mehmed’s victory as the fulfilment of this prophecy, elevating the young sultan to near-legendary status as “Ghazi” (holy warrior) and “Fatih” (the Conqueror). Indeed, ever after, Mehmed II would be commonly known as Mehmed “the Conqueror” for this singular achievement. The city that the Ottomans called İstanbul was now the jewel of Mehmed’s realm. With Constantinople as his capital, Sultan Mehmed II had dramatically vaulted the Ottoman state from a regional power to an imperial one. But the Conqueror was far from finished – in his mind, Constantinople was just the beginning.

Conquests in the Balkans

With Constantinople secured, Mehmed II turned his attention to consolidating and expanding his empire, especially in the Balkans of Southeastern Europe. In the years immediately following 1453, the sultan launched a series of campaigns to bring remaining Christian kingdoms and lordships in the region under Ottoman dominion. These campaigns were a mix of calculated diplomacy and uncompromising force, as Mehmed pressed the advantage gained by his greatest victory.

Subjugating Serbia and the “Wall of Belgrade”

One of Mehmed’s first targets was the Serbian Despotate, a kingdom that had long been a tributary vassal to the Ottomans but still maintained a degree of autonomy. Serbia’s ruler, Đurađ Branković, had a complex relationship with the Ottomans – he was actually the father-in-law of Murad II and had paid tribute intermittently. By the mid-1450s, however, Branković leaned toward Hungary for support against growing Ottoman dominance, and he delayed payments of tribute. Mehmed saw an opportunity to press Serbian subordination by force. In 1454, Ottoman armies marched into Serbian lands. Mehmed’s forces captured a series of fortresses and towns on the frontier and even skirmished with a Serbian cavalry force, which they put to flight. They besieged Smederevo, the Serbian capital on the Danube River. Before Smederevo could fall, news came that John Hunyadi – the same Hungarian warlord who had opposed Mehmed before – was leading a relief army south. Mehmed prudently lifted the siege and withdrew that time, avoiding a pitched battle with Hunyadi’s larger Christian force.

The following year, after securing peace elsewhere, Mehmed returned to Serbia to finish the job. In 1455, he laid siege to Novo Brdo, a wealthy mining city in the Serbian interior (famed for its silver mines). The city’s defenders held out for about forty days, enduring relentless Ottoman cannon bombardment, before Novo Brdo surrendered. Mehmed then mopped up surrounding towns, effectively crippling Serbian resistance. Sultan Mehmed’s campaigns in Serbia were noted for their severity – by Ottoman accounts, tens of thousands of Serbian prisoners were taken, and many were resettled in Ottoman territories to prevent future rebellion.

In 1456, Mehmed II set his sights on a far more formidable obstacle: the fortress city of Belgrade. Belgrade (known then as Nándorfehérvár) was a bastion guarding the Hungarian frontier on the Danube, and it was the one major stronghold in the central Balkans that still blocked Ottoman expansion northward. Mehmed understood that capturing Belgrade would open the gates of Hungary and solidify Ottoman control in the region. He gathered a large army – contemporary rumours spoke of tens of thousands of troops – and personally led the campaign, bringing along a flotilla of river warships to assist from the Danube. Arriving at Belgrade in July 1456, the Ottomans commenced a heavy bombardment. Twenty-two enormous cannons pounded the walls day and night, gradually crumbling sections of the medieval fortifications. Mehmed’s troops filled the moat with rubble and prepared for a grand assault.

However, the Hungarian defender of Belgrade was none other than John Hunyadi – a seasoned general and national hero determined to save the fortress. Hunyadi, with a relief force and peasant crusaders inspired by a charismatic friar, managed to slip reinforcements into Belgrade and even sank much of the Ottoman river fleet in a dramatic nighttime sortie. On July 21, 1456, Mehmed ordered a massive attack, and furious close combat raged on the breached walls. Ottoman troops at one point broke into the city, leading to brutal street fighting. But the Christians, motivated by desperation, counterattacked fiercely. In the chaos, the Sultan himself joined the fray, displaying personal bravery. Mehmed II fought with sword in hand on the front lines, reportedly killing several enemy soldiers, until he was seriously wounded – struck by an enemy arrow or spear. The injury forced Mehmed out of the battle. Leaderless and battered, the Ottoman troops began to falter. Hunyadi’s men surged and pushed them back to the Ottoman camp. The wounded Mehmed, refusing to flee, helped rally his soldiers to prevent a complete rout, but the battle was lost. Belgrade had withstood the Ottoman onslaught. It was one of the few outright military defeats in Mehmed’s career and effectively halted Ottoman expansion into Hungary for decades.

Sultan Mehmed withdrew to Edirne to recuperate, frustrated by the failure at Belgrade. The fortress earned a heroic reputation in Europe as “the bulwark of Christendom,” while Mehmed licked his wounds. Interestingly, had Belgrade fallen in 1456, the Ottomans might have swiftly overrun much of Hungary. Instead, the stalemate held. Not long after, John Hunyadi died of an illness, and Serbia’s despot Đurađ Branković also passed away (late 1456), leaving Serbia leaderless and vulnerable. In the ensuing power vacuum, Mehmed saw his chance. In 1458–1459, after a brief internal struggle among Branković’s heirs, the Ottomans moved in to annexe Serbia outright. Mehmed’s grand vizier, Mahmud Pasha Angelović, led Ottoman forces that captured remaining Serbian strongholds, including the great fortress of Smederevo in June 1459. With that, the Serbian Despotate ceased to exist; its lands became Ottoman provinces. The fall of Serbia plugged a major gap in Mehmed’s European domains. By the end of the 1450s, nearly the entire central and southern Balkans—from the Aegean up to the Danube—lay under the rule of Mehmed “the Conqueror.”

Portrait of Vlad (Dracula) the Impaler, Prince of Wallachia, 1460

Conflict with Vlad the Impaler

Even as he subjugated Serbia, Mehmed II faced a notorious foe in the Danubian principality of Wallachia (now southern Romania). This region, dense with forests and marshes, was ruled by the Voivode Vlad III, later infamous in legend as “Vlad the Impaler” (and the inspiration for the Dracula myth). Vlad III had a complicated history with the Ottomans. As a boy, he and his younger brother Radu were hostages at the Ottoman court, a common practice to ensure their father’s loyalty. There, Vlad learned Turkish and Ottoman customs – and also developed a fierce hatred for his captors. By the mid-1450s, Vlad III had seized the Wallachian throne and was technically an Ottoman vassal expected to pay annual tribute. But Vlad was independent-minded and brutal. In 1459, when Mehmed’s envoys arrived to collect the overdue tribute of 10,000 gold ducats and recruit young Wallachians for Ottoman service, Vlad III refused. According to one famous tale, he executed the Turkish diplomats by nailing their turbans to their skulls, declaring that “this is how we show respect” in Wallachia. It was a deliberate provocation and an open breach of fealty.

Mehmed II was furious. Still occupied with Serbia and other campaigns, the sultan initially dispatched a contingent of troops under one of his commanders to discipline Vlad. But Vlad III was a wily and ruthless opponent. In the winter of 1462, Vlad launched a shocking offensive: he led his own forces across the Danube into Ottoman territory, taking advantage of winter ice to move swiftly. Using stealth and intimate knowledge of Ottoman ways, Vlad’s men fell upon unsuspecting towns between Serbia and the Black Sea. They massacred thousands of Turkish villagers and soldiers, sparing no one. In a chilling letter to the King of Hungary, Vlad bragged that in a short span he had killed “23,884 Turks” (not counting those burned in their homes). The voivode’s preferred method of execution – impalement on wooden stakes – lent him his grisly nickname. Tales spread of Vlad III creating “forests” of impaled victims to terrorise his foes.

Faced with this brazen challenge, Mehmed II decided to personally lead a punitive campaign. In the spring of 1462, the sultan marched north with a force perhaps 90,000 strong, including his elite Janissaries and cavalry, determined to crush the Wallachian prince. Vlad could not face Mehmed in a pitched battle – his army was smaller and less equipped – so he turned to guerrilla tactics. As Mehmed’s columns advanced into Wallachia, Vlad’s men harassed them with sudden raids, disappearing into the woods. The voivode also implemented a scorched-earth policy, poisoning wells and burning villages to deny the Ottomans supplies. The peak of Vlad’s resistance came on the night of June 17, 1462, when he led a daring night attack on the Ottoman camp near Târgoviște. Disguising some of his soldiers in Turkish attire, Vlad infiltrated the camp after dark and launched a sudden assault, hoping to assassinate Mehmed II amid the confusion. Accounts say Vlad’s raiders came close to the sultan’s tent, sowing chaos, but they failed to find Mehmed himself. Dozens of Janissaries and Ottoman officers were slain in the melee before Vlad retreated into the forests. By dawn, hundreds lay dead, and the Ottoman camp was in disarray, though Mehmed II survived unscathed.

Despite Vlad’s terrifying tactics, the numerical superiority of the Ottoman army began to tell. Mehmed advanced to capture the Wallachian capital of Târgoviște – only to be greeted by a ghastly sight outside the city: a field of impaled corpses, the remains of Turkish prisoners arranged by Vlad as a psychological weapon. The macabre display did give Mehmed pause, but it did not halt his campaign. Wallachia simply proved too hostile and wild to conquer outright, and Mehmed’s goal shifted from killing Vlad to replacing him. The Sultan had a convenient alternative ready: Vlad’s own brother, Radu the Fair, had been raised in the Ottoman court and was friendly to Mehmed. As the Ottoman army pressed on, many local boyar nobles, weary of Vlad’s harsh rule, defected to the Ottomans and accepted Radu as the new prince. Vlad III was forced to flee northward; by the autumn of 1462, he had sought refuge in Hungary (where he was ironically imprisoned for a time).

Mehmed II installed Radu as a client ruler in Wallachia, thus achieving a political victory without the burden of occupying a resistant land. The conflict with Vlad the Impaler would live on in legend and literature, but for Mehmed, it was just another rebellious vassal tamed. Wallachia remained under intermittent Ottoman influence, and Vlad III would only briefly regain power years later (before meeting a violent end). The sultan had demonstrated both resolve and pragmatism: he neutralised a dangerous foe and reminded other vassal states of the grim fate awaiting those who defied “the Conqueror.”

Bosnia and the End of a Kingdom

By the early 1460s, Mehmed II had eliminated or vassalized most of the independent powers in the Balkans with two conspicuous exceptions: the Kingdom of Bosnia and the mountainous stronghold of Albania (more on Albania shortly). The Kingdom of Bosnia, located to the west of Serbia, had thus far avoided direct conquest by maintaining a tributary relationship with the Ottomans. However, its young king Stephen Tomašević (crowned 1461) made a fatal miscalculation. Feeling insecure on his throne and hoping for Western assistance, Stephen stopped paying the yearly tribute to Mehmed and appealed to the Pope and Hungary for help. This open defiance gave Mehmed his casus belli.

In the spring of 1463, Sultan Mehmed II swept into Bosnia at the head of a well-organised force. The campaign was swift and decisive. The Ottomans first seized the important fortress of Bobovac, the royal seat where Bosnia’s crown jewels were kept – its quick capitulation shocked the Bosnians. King Stephen fled from one fort to another, desperately seeking refuge. Mehmed’s army pressed onward, taking Jajce and then Ključ, where Stephen Tomašević was eventually captured. The 25-year-old king was brought before Mehmed II, who initially assured him of mercy. But perhaps due to broken oaths or the sultan’s own resolve to make an example, Stephen was executed, reportedly beheaded on Mehmed’s orders. With his death, the independent Kingdom of Bosnia was extinguished. Many of its nobility either fled or were also killed, while some converted to Islam and were co-opted into the Ottoman system.

Mehmed annexed Bosnia, making it the westernmost Ottoman province in Southeastern Europe. The fall of Bosnia in 1463 deeply alarmed the nearby Kingdom of Hungary and the Republic of Venice, which suddenly shared a border with the expanding Ottoman realm. Indeed, these powers would soon try to counter Mehmed’s gains, leading to one of the longest wars of his reign. But for the moment, Mehmed II had achieved an extraordinary transformation of the Balkan political landscape. In little over a decade, he had wiped away the last vestiges of Byzantine rule and absorbed Serbia, the Morea, and Bosnia. Only a few pockets of resistance remained in the Balkans – most notably in Albania and in some coastal cities under Venetian control. The Conqueror’s appetite for expansion was hardly sated, and conflict with the remaining Christian powers in the region was inevitable.

War with Venice and the Last Crusaders

Mehmed II’s rapid conquests in the 1450s and early 1460s did not go unnoticed by the maritime Republic of Venice, a major power in the Mediterranean with colonies and trading interests all around the Aegean and Adriatic seas. Tensions between the Ottomans and Venice had been on the rise – traders quarrelled, borders rubbed, and each side harboured distrust of the other’s intentions. When Bosnia fell in 1463 and the Ottoman frontier reached the Adriatic, Venice grew alarmed. That same year, Pope Pius II succeeded (for the last time in history) in proclaiming a new crusade against the Ottomans. Although the Pope’s own crusading fleet never materialised (he died shortly after), Venice and the Kingdom of Hungary took up arms. Thus began the Ottoman–Venetian War of 1463–1479, a long and costly struggle that would test Mehmed’s empire.

The opening moves favoured the Christian allies. In late 1463, a Venetian army landed in Greece and, with local Greek support, managed to retake the strategic Peloponnesian fortress of Argos. They also rebuilt the Hexamilion wall across the Isthmus of Corinth, briefly blocking Ottoman access to the Morea (southern Greece). Meanwhile, the Hungarian king Matthias Corvinus seized some fortresses in Bosnia, including the old Bosnian capital of Jajce, denying them to the Ottomans. Mehmed II moved quickly to respond on multiple fronts. He dispatched his capable Grand Vizier, Mahmud Pasha, to Greece. In 1464, Mahmud Pasha’s forces burst into the Peloponnese, shattered the Hexamilion (the wall was smashed apart for the second time in 20 years), and forced the Venetians into retreat. Argos and other towns that had briefly welcomed Venetian rule were brought back under the Ottoman fold. Mehmed himself marched into Bosnia to counter Matthias Corvinus. The sultan’s attempt to recapture Jajce in 1464 failed after a tough siege – the fortress held out, and Corvinus’s approaching army forced an Ottoman withdrawal. For the time being, the Kingdom of Hungary managed to create a buffer in northern Bosnia.

The war ground on indecisively. Venice, for all its naval strength, struggled to defend its far-flung Greek possessions. The Venetians launched raids and seized Aegean islands when they could, while the Ottomans gradually tightened their grip on remaining Byzantine holdouts. One by one, even the last independent Greek regions fell: in 1460, Mehmed had completed the conquest of the Morea by taking Mistra, and in 1461, he had compelled the surrender of the distant Empire of Trebizond on the Black Sea coast (bringing an end to the final Byzantine splinter state). Venetian-controlled islands like Lesbos (Mytilene) were attacked – in 1462, Mehmed’s fleet captured Lesbos from its Genoese lords (allied to the Venetians). Venice attempted counterstrikes, but with mixed success. A turning point came in 1470, when Mehmed II personally led a massive combined land-sea operation to capture Negroponte (Euboea), the largest island in the Aegean still in Venetian hands. After a brutal siege of the fortress of Chalkis, the Ottomans overran Negroponte, shocking Venice with the loss of one of its richest eastern colonies.

Throughout these campaigns, Mehmed displayed not only military might but also strategic tenacity. The war saw episodes of high drama – for example, the famed Albanian resistance leader Skanderbeg, who had fought the Ottomans for decades, allied with the Venetians. Mehmed launched invasions of Albania in 1466 and 1467 to finally eliminate Skanderbeg’s revolt. He built the fortress of Elbasan deep in Albania to secure Ottoman control. Yet Skanderbeg’s guerrilla tactics and support from Italy frustrated Mehmed until Skanderbeg’s death in 1468 effectively dissolved the organised Albanian resistance. Afterwards, the remaining Albanian strongholds gradually fell; by 1478, the tough citadel of Krujë had been starved into surrender, and the last Venetian-held city in Albania, Shkodra, only succumbed after an epic siege (and was ultimately handed over by treaty).

By the late 1470s, both sides were exhausted. Venice had suffered financially crippling losses – its trade had been disrupted, and attempts to mobilise Europe’s monarchs into a grand crusade had failed. Mehmed II, while victorious in many battles, found the Venetian navy to be a persistent nuisance and the costs of war draining even for the wealthy Ottoman treasury. In 1479, after protracted negotiations, the Ottomans and Venice agreed to the Treaty of Constantinople (1479). The peace terms reflected Ottoman dominance: Venice ceded key territories, including Shkodra and other forts in the Balkans, yielded the island of Negroponte and several Aegean islands to Mehmed, and agreed to pay a hefty war indemnity plus an annual tribute of 10,000 ducats for the privilege of trading freely in the Black Sea. The proud Venetian Republic had to bow, at least temporarily, to the reality of Ottoman power.

By the end of this war, Mehmed II had effectively secured the Balkans as the Ottoman Empire’s backyard. The Republic of Venice still held a scattering of island bases and coastal outposts, but it was clear that the Ottomans were now the pre-eminent power in the Eastern Mediterranean. Only the distant Latin stronghold of Rhodes, held by the Knights of St. John, and the Hungarian frontier remained as major checks to total Ottoman hegemony in Southeast Europe – and Mehmed had plans for those as well.