The Battle and Fall of Constantinople, 1453. Islamic Turks Take the Invincible City, Age of Exploration Hastened.

This battle shattered the Byzantine Empire once and for all, flinging open Europe’s doors to the advancing tide of Islam. It was the moment the Ottoman Turks seized their mantle as the supreme Muslim power, a position they would hold, unchallenged, for nearly five centuries—until the dawn of the twentieth century.

Constantinople. February - March, 1453.
Turkish Ottoman Forces: 90,000 Soldiers.
Byzantine Forces: ~ 10,000 Soldiers.

Additional Reading and Research:

• Fuller, J.F.C. A Military History of the Western World.
• Norwich, John. Byzantium: The Decline and Fall.
• Runciman, Sir Steven. The Fall of constantinople - 1453.
• Antonucci, Michael. Siege Without Reprieve, Military History Magazine, April 1992.

Some Historical Notes:

1. Constantine the Great established Constantinople as his capital in 330, not 323. While Constantine began work on Constantinople in the 320s, the formal dedication of the city as his new capital occurred in 330 AD.
   While my depiction of Muhammad's rise during the weakness of the Byzantine and Persian Empires is broadly accurate, it’s important to note that Muhammad himself did not conquer Byzantine or Persian territories; that was the work of his successors, the Rashidun caliphs, particularly under the leadership of Abu Bakr, Umar, and their generals in the early Islamic conquests. These conquests began after Muhammad's death in 632 AD. I have multiple episodes on this that might interest any listeners.
   
   
2. The term “Arab merchants” and the fall of Constantinople. The Ottoman Turks, not Arabs, were the ones who conquered Constantinople in 1453, and they controlled trade in the eastern Mediterranean afterward. Arab merchants had dominated long-distance trade earlier in history, but after the rise of the Ottoman Empire, the Ottomans themselves held much of the control over trade.
   
   
3. Mohammed II vs. Mehmed II. Throughout my account, I refer to Sultan Mohammed II (also spelled Mehmed II) arriving at the walls of Constantinople in April 1453. Mohammed II, also known as Mehmed the Conqueror, the son of Murad II, are interchangeable.
   
   
4. Venetian fleet and the siege timing. The mention of a Venetian fleet arriving too late and turning back upon seeing the fall of the city is often debated among historians. While it's true that various European states, including Venice and Genoa, were slow to respond, the role and timing of any fleets arriving too late or turning back isn't well-documented with clear evidence. It’s a compelling image, but historians still debate this. Some ships did manage to break the blockade earlier in the siege, but the idea of a "rescue fleet" arriving right at the moment of the city's fall is not confirmed by all sources.
   
   
5. Martin Luther and the Reformation connection. The fall of Constantinople in 1453 was indeed a seismic event that affected European politics, religion, and culture, but the link between this event and Martin Luther's Reformation in 1517 is more indirect. While the Eastern Orthodox Church’s survival under Ottoman rule certainly had an impact on European religious dynamics, Luther's movement was more directly a reaction to the abuses and practices of the Roman Catholic Church in the early 16th century, rather than a direct result of the fall of Constantinople.
   
   
6. The Hagia Sophia’s conversion timeline. I said that within a week of the fall, the Hagia Sophia was hosting Muslim services. In fact, Mehmed II ordered the conversion of the Hagia Sophia into a mosque almost immediately after the city's capture, though Muslim sources state that "within a week" regular services began.

Transcript

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With our superpowers and global trade, its hard or us modern people to conceptualize the fall of a city and the emotional havoc it would often reap on the people, of course those that called the city home… but I’m referring to the people at large — those who had perhaps never been there, or pileramged to once in their lives. Constantinople was the guardian of Europe from their considered infidels, the Muslims. And it was the guard that kept Islam, from their considered infidels, the Christians. It had stood for over 1100 years without being breached, and lived through 20 significant sieges, victorious each time.

In an age where superstitions and religion was more than an aspect of life — it was life itself, to have a city that was the seat of Christendom in the beginning of Christianity as the official religion of the Roman Empire, then defended Christians in Europe from encroaching Islamic forces, a city that stood at the very bridge from Europe to Asia, to have it fall would be like having Washington DC taken over by aliens, multiplied by 100. It’s just something very hard for us to understand in our modern era.

The fall of this city was mourned with true earnestness throughout Europe. You know, there was an apocryphal quote: "If the world was a county , Constantinople would be its capital". 

But like all historical moments of precipice, the fall of this city had effects that would bring us into the age of exploration. 

Let us now experience, the siege and fall of Constantinople. 

Welcome to History's Greatest Battles, Season One, Episode 59: The Battle of Constantinople. February through may of 14 53.

Byzantine Forces: fewer than 10,000 soldiers.
Turkish Forces: roughly 90,000 soldiers.

This battle shattered the Byzantine Empire once and for all, flinging open Europe’s doors to the advancing tide of Islam. It was the moment the Ottoman Turks seized their mantle as the supreme Muslim power, a position they would hold, unchallenged, for nearly five centuries—until the dawn of the twentieth century.

In 323 AD, Constantine the Great seized Byzantium, a city that for centuries had dominated the choke point between Asia and Europe. With audacity only an emperor could muster, he declared it his new capital—Constantinople—staking his claim to the crossroads of the known world.

The Sea of Marmara, hemmed in by the Bosporus to the northeast and the Dardanelles to the southwest, forms the fragile thread linking the Mediterranean to the Black Sea, and through these slender veins of water flowed the ambitions of empires. Without these straits, no man could march from Europe to Asia Minor without venturing around the vast Black Sea. The city—Byzantium, Constantinople, or Istanbul—was the key. Whoever held it controlled the lifeblood of land and naval warfare, and the pulse of trade that fed both continents.

As Rome's grandeur withered, Constantinople ascended, claiming the mantle of empire. It became the heart of the Eastern Roman—or Byzantine—Empire, not merely a political titan ruling over the Mediterranean and the Middle East, but also the sacred stronghold of the Greek Orthodox Church, locking horns with the pope in Rome for the very souls of Christendom. Yet, in the final reckoning, it was not politics, but the clash of faiths that would bring Constantinople to its knees.

In the seventh century, the desert sands of Arabia bore witness to the rise of Mohammed, the Prophet of Islam. With the Qur’an as his divine revelation, he proclaimed a new order—the final chapter in God's plan. And he would carry it forth not just by word, but with sword in hand. Whether by chance or the hand of fate itself, Mohammed emerged at the perfect moment. Persia and the Byzantine Empire, once towering powers, had torn at each other’s throats until both were on the brink of collapse, ripe for the taking. Mohammed capitalized, forging a vast empire as his faith swept across the lands like wildfire. Persia and Byzantium hemorrhaged territory and believers alike. Many flocked to Islam, finding relief from the suffocating grip of Orthodox rule.

For seven centuries, Islam and Orthodoxy clashed, each rising and falling like storm-tossed titans, locked in an endless struggle for dominion. By the fifteenth century, what had once been the great Byzantine Empire was reduced to a mere shadow of its former self. Constantinople, that jewel of empires, stood alone, guarding a handful of Aegean islands like an old lion watching over the last scraps of its territory.

The earlier Islamic threat had stirred the Crusades in the twelfth century, yet rather than unite Christendom, it deepened the schism between Catholic and Orthodox, driving them further apart when unity was most needed. In 1452, Sultan Mohammed II, son of Murad II, cast his eyes upon Constantinople with unrelenting desire. His decision was final: the city would be his. Yet, when Constantinople's desperate pleas for aid echoed across Europe, they were met with deafening silence. England and France, exhausted from the blood-soaked Hundred Years' War, had no strength left to spare. Germanic and Spanish rulers whispered promises of aid, but delivered nothing but empty words.

Only in Italy did the cries of Constantinople find faint echoes of hope. Genoa and Venice, driven by their mercantile interests, feared Arab merchants seizing the city’s trade. Rome, always calculating, offered help—but only if the Orthodox Church bent the knee to the Pope. Desperate to save his crumbling empire, Emperor Constantine XI Paleologus swallowed his pride and struck a deal with Rome. In exchange for submission, he received a pittance—200 archers—hardly enough to bolster his threadbare defenses. His decision ignited fury among many Byzantines, who spat at the thought of Roman interference, some even muttering that Turkish rule would be preferable.

In the spring of 1452, Mohammed II made his first move. He dispatched 1,000 masons to the Bosporus, ordering the construction of a fortress to ensure his troops’ safe passage across the straits, signaling that his conquest had begun. Constantine, powerless to halt the advance, could do little but voice his objections. His forces numbered a paltry 5,000 native men, bolstered by only 2,000 foreign soldiers—a feeble host for what was to come. Yet, tradition stood as his ally. Constantinople's triple walls, though weathered by time, had withstood the fury of twenty sieges. Even in their current state, they embodied the resilience of an empire that refused to die.

In January 1453, a glimmer of hope arrived in the form of Giovanni Giustiniani, an Italian mercenary renowned for defending walled cities. He brought with him 700 battle-hardened knights and archers, ready to test their mettle against the Sultan’s might. Giustiniani’s reputation as a master of siege defense was well-earned, but Mohammed II had his own European ally—Urban, a Hungarian cannon maker. Urban furnished the Sultan’s army with seventy cannons, including the monstrous "Basilica," a 27-foot behemoth that hurled 600-pound stone balls with devastating precision. Though the "Basilica" could fire only seven times a day, each shot was a thunderous blow, shattering everything it touched, including the formidable walls of Constantinople.

The remainder of the city relied on a single wall that circled its seaward edges, a thin barrier standing between Constantinople and the advancing storm. Mohammed, focusing his forces to the north across the Bosporus, left the city’s southern flank exposed to the Mediterranean, a gap in the city’s defenses that could be exploited if relief ever came. The entrance to the Golden Horn, Constantinople’s primary harbor, was sealed by a massive chain boom, reinforced by twenty-six war galleys. This was the city’s lifeline, the only avenue for rescue, if rescue were to come at all.

On April 6, 1453, Sultan Mohammed II arrived at the gates of Constantinople with an army 90,000 strong. His force included 70,000 disciplined regulars and 20,000 ruthless Bashi-Bazouks, men driven by the promise of plunder once the city lay in ruins. At the core of his army stood the Janissaries, elite slave-soldiers ripped from Christian families as children, forged in a brutal military upbringing, and loyal only to the Sultan. Clad in heavy armor and unmatched in skill, the Janissaries were now armed with a deadly innovation: personal firearms, a weapon that would change the face of battle.

Mohammed’s opening move was swift. He seized the town of Pera, just across the Golden Horn. Though it seemed a minor victory at first, its implications would reverberate through the siege. With Pera secured, Mohammed positioned his forces before the city’s western walls, bracing for the long and bloody siege ahead. The northern flank, defended by a solitary wall near the imperial palace, became the focal point of Emperor Constantine’s defenses. In the Blachernae quarter, he concentrated his best soldiers, knowing it would soon face the brunt of the assault.

On April 18, after twelve relentless days of bombardment, Mohammed deemed the time ripe for an attack. His cannons had torn a narrow breach in the walls, but the Byzantines held firm. Their defenders slaughtered 200 of Mohammed’s men and repelled the rest without suffering a single loss. Two days later, on April 20, the sharp-eyed lookouts on Constantinople’s sea-wall spotted sails on the horizon. Four ships—three Genoese vessels loaded with men and supplies from Rome, and a Byzantine ship laden with grain from Sicily—approached from the south. In a brutal naval clash with the Muslim fleet, these ships fought tooth and nail, managing to break through the blockade and clear the chain boom, sailing triumphantly into the safety of the Golden Horn.

Furious at this breach, Mohammed realized that to conquer the city, he had to dominate the harbor. Unable to force the chain boom, he conceived a daring plan. He ordered his ships to be dragged overland, through the streets of Pera, into the harbor. By April 22, thirty Turkish vessels sailed into the Golden Horn, the result of an engineering marvel that defied belief. The Byzantines launched a desperate counterattack, but treachery lurked in their midst. Betrayed by one of the Sultan’s spies, they succeeded in sinking just one Turkish ship. Despite this remarkable Turkish achievement, the presence of their fleet in the Golden Horn did little to alter the course of the siege.

Mohammed pressed on with his relentless bombardment. By May 6, his cannons had torn open another gaping breach, this time at the Gate of St. Romanus, where the Lycus River slipped into the city. Giustiniani, ever the tactician, knew better than to repair the wall under fire. Instead, he erected a fresh barrier behind the breach, turning the damage into a temporary obstacle. On May 7, the Turks hurled 25,000 men at the walls, but after three brutal hours of combat, the Byzantine defenders threw them back, bloodied and broken. Five days later, on May 12, the Turks breached the wall at Blachernae. The situation teetered on the edge of disaster, but Constantine, leading the Imperial Guard himself, rushed in to plug the breach and hold the line.

Frustrated by his failures, Mohammed turned to undermining the walls with tunnels. But Constantine had a secret weapon in his engineer, Johannes Grant, who ferreted out every mine the Turks dug. With explosives, flooding, and even the dreaded Greek fire, Grant destroyed all fourteen tunnels before they could inflict any damage. Undeterred, Mohammed resolved to scale the walls. He had a massive siege tower built and wheeled it toward the Charisius Gate, the northernmost entry to the city. The city’s bombardment had already shattered one of the defensive towers. The siege tower, now looming over the walls, rained down covering fire as Turkish soldiers began filling the moat, inching ever closer to the city’s heart.

In a bold move, Constantine called for volunteers to launch a daring counterattack against the siege tower. Against all odds, the operation was a stunning success. Catching the Turkish guards off-guard, the Byzantines doused the wooden structure with Greek fire, reducing it to ash. As the tower burned, the city’s defenders worked through the night, rebuilding their shattered walls. When dawn broke, Mohammed beheld the smoking wreckage of his siege tower, the ruins lying beneath the gleaming, freshly rebuilt walls of Constantinople.

In both camps, tensions ran high. Constantinople’s defenders, exhausted to the bone and with supplies dwindling, knew their time was running short. Across the battlefield, Mohammed’s officers debated fiercely, with some urging the Sultan to abandon the siege before the much-whispered rescue fleet arrived to tip the scales. But Mohammed’s will was iron. Siding with those who urged relentless assault, he resolved to launch one final, decisive attack—one last push before either victory or retreat.

The Lycus River entrance, where the walls had been battered and bruised beyond repair, became the chosen site for Mohammed’s last great gamble. There, the Sultan would strike with everything he had left. A spy within the Turkish ranks brought word to Constantine of the coming assault, but the Emperor faced a grim reality: his men, weary and battered from weeks of constant battle, had little left to give. Could they survive one last storm?

At 2:00 AM on May 29, the final storm broke. The Bashi-Bazouks, wild and reckless, hurled themselves at the Byzantine walls with savage fury. For two brutal hours, the defenders rained death upon them with arrows and gunfire, cutting them down in waves. But the relentless fighting drained the strength of the Byzantines with each passing minute. No sooner had the first assault been beaten back than Mohammed unleashed the second wave, not giving the defenders a moment to breathe. These were his regular troops—disciplined, well-armed, and battle-hardened. But the narrow breach funneled their attack, allowing the defenders to focus their firepower. Once again, the Byzantines held their ground, sending the Sultan’s men reeling.

After two more hours of grinding combat, the Byzantine defenders were nearly spent, barely able to stand. And now the Janissaries, Mohammed’s elite force, marched forward. Constantine’s men, driven by sheer will and desperation, fought like demons and threw back this wave as well. The defenders, though shattered, held—again. But even as the Janissaries faltered, fate turned its hand. A small group of Turkish soldiers stumbled upon an open gate, left unsecured in the chaos of battle. Seizing the moment, they slipped inside, and before the Byzantines could react, the gate was lost.

The Turks swiftly captured a tower near the Blachernae quarter and raised the Sultan’s banner high above it. Panic spread through the Byzantine ranks like wildfire—the northern flank had been breached, or so the rumor went. At that very moment, Giovanni Giustiniani, the city’s last hope, was struck down by a grievous wound. As word of his injury spread, his men faltered, their morale shattered. The combined shock of their commander’s fall and the news of the northern breach sent the defenders into retreat, stumbling backward in the face of disaster. Mohammed seized the moment without hesitation. He unleashed another wave of fresh Janissaries, who surged forward, clearing the space between the walls and seizing the Adrianople Gate. Once it fell, the floodgates opened, and Turkish troops poured into the city like a tidal wave.

Emperor Constantine XI, knowing the end had come, took up arms and led the remnants of his forces into the teeth of the Turkish onslaught. He fought and died amid the chaos, sacrificing his life for the city and empire that had been his charge. His death marked the end for nearly all who stood with him. The co-defenders, and countless civilians, were cut down as the Turks swarmed through the city, unleashing a wave of destruction and looting that consumed Constantinople.

Mohammed II, while restraining the worst of the pillage, allowed much of the city to be ransacked, sparing only the finest buildings for his own claim. He forbade their ruin, keeping them as symbols of his conquest. The Sultan claimed the mighty Church of St. Sophia for himself, and within a week, the great Hagia Sophia rang not with Christian hymns, but with the calls to prayer of Islam. As Turkish banners fluttered over the once-great city, thirty Venetian ships, too late to offer aid, glimpsed the conquest from the sea. They turned around and sailed home, bearing the grim news.

When the storm of looting finally subsided, the survivors were rounded up. Those not slain were enslaved—perhaps 50,000 souls shackled and marched into captivity. Thus fell the bastion of eastern Christendom, the city that had withstood the onslaught of empires for over 1,100 years. Constantine the Great’s proud city was no more. For Mohammed II, this was only the beginning. Constantinople’s fall was but one step in his march of conquest, as he went on to subdue Greece and most of the Balkans in the next 28 years of his reign.

Western Europe, which had all but abandoned Constantinople in its hour of need, reeled in shock. A city that had withstood centuries of enemies had finally been brought low, and the implications sent shudders across Christendom. In Rome, the Catholic Church despaired. The eastern Christians they had long sought to convert now fell swiftly under the banner of Islam, slipping beyond their reach. Yet, against all odds, the Eastern Orthodox Church survived. Mohammed allowed the patriarch George Scholarius to retain his position, keeping the Church alive, though far removed from the Catholic grip.

The Church, though humbled, remained a force in the East, beyond the Pope’s dominion. Its resilience inspired those who resented the yoke of Rome’s rule. And within sixty years, Martin Luther would rise, leading a protest that sparked the Reformation and shattered Catholic supremacy in the West. Genoa and Venice trembled at the thought of their new overlords—Arab merchants who now held the keys to all the goods flowing from the East, driving a hard bargain at every turn. The cities of eastern Europe braced themselves, as the Turkish war machine loomed on the horizon. Austria, in particular, would spend the next 450 years locked in an unyielding struggle against the ever-encroaching Ottoman Empire.

The Ottoman Turks, who had long clawed their way to dominance in the Muslim world, now stood unchallenged as the supreme power. Their empire stretched across the Balkans, the Middle East, and vast swaths of North Africa, rivaling the reach of the Byzantines at their peak. For more than a century, the Ottomans ruled the eastern Mediterranean’s waves, until Christian forces broke their naval dominance at the Battle of Lepanto in 1571. Yet, from this devastation came an unexpected boon for Western Europe. A flood of refugees from the fallen Byzantine Empire, especially from Greece, poured into Italy, bringing with them vast troves of knowledge that fueled the blazing fires of the Renaissance.

Italian merchants, outraged at the steep prices demanded by Muslim middlemen for spices and silks from the East, began seeking new paths to these precious goods, igniting an age of exploration. Within three decades, Portuguese ships began probing the African coast, searching for routes to India and China. Not long after, the Genoese navigator Christopher Columbus persuaded the Spanish crown to back his audacious vision of a new route to the East—a journey that would reshape the world. Indeed, it was the fall of Constantinople that hastened the dawn of the Age of Exploration, setting Europe on a course that would forever alter the map of the world.