In 1452, Constantine XI Palaeologus ruled over a Byzantine empire that consisted of no more than a few small islands and the city of Constantinople itself. The city at that time was no more than a feeble image of the great imperial capital it once had been. The population had dwindled from more than 1 million residents to about 50,000. The army that could once field tens of thousands of fully armored cavalry now consisted of fewer than 7,000 men, including mercenaries.

What did remain unchanged were Constantinople’s massive walls. The entire city was surrounded by at least one thick and high wall, even where the city directly adjoined the water. On its more vulnerable eastern side, Constantinople was defended by double walls with a smaller outer wall six feet thick and twenty-five feet high and an inner wall, or great wall, that was more than twenty feet thick and forty feet high. There was a thirty-foot-deep ditch between these walls. A road ran inside each wall to allow quick and sheltered movement, and only small gates allowed access between them. Most of the gates were on the eastern wall and even more formidable than the wall itself.

Mohammed II ruled a Turkish empire that controlled all of the Mideast and parts of Africa. He wanted to expand his control into Europe, but, as it had for more than a thousand years, Constantinople blocked the way. He gathered an army and built a fort to cover his crossing into Europe near the city. There was no question of his intentions and no way for Constantine XI and his city to avoid a siege.


The defenses of Constantinople

Constantine put out a call for help to all of Christendom. He got very little response. The kings of France and England sent nothing. The pope demanded the Eastern Church recognize his authority. It was a bitter demand for the other center of Christian faith; even so, the Byzantine emperor agreed. When he did, the pope sent only 200 bowmen. The only real reinforcement that arrived in time was a mercenary who was an expert in defending walls. The mercenary brought with him 700 skilled soldiers. But men trickled in until, by the end of the year, the city’s garrison had risen to 10,000. Across the straits, Mohammed II waited with almost 100,000 men, and more were being mobilized in various parts of his vast empire.

One other mercenary group answered the Byzantine ruler’s call for help. In 1452 gunpowder weapons were just beginning to change warfare forever. Artillery was large, temperamental, and dangerous to fire. Gunners often made their own gunpowder and just as often cast their own cannon as well. The men who operated the cannons were civilian specialists who were paid highly because of the risk and the skills required. Among the greatest of the mercenary cannoneers of this time was Urban of Hungary. Hungary was a Christian kingdom, so before the siege began, Urban offered himself, his cannons, and his men to Constantine XI. Those cannon ranged from small guns that fired a metal or stone ball less than a few pounds, to one named “Bassilica” that could fire only seven times per day but threw a ball that weighed upward of 600 pounds. Now, if the strength of Constantinople was in its wall, you might think that its ruler would understand that the cannons would pose the biggest threat to the walls. But Constantine XI decided the mercenary gunners and their guns were too expensive to hire. Even though there was a good chance that Urban would offer his cannon to Mohammed, for reasons of his own, Constantine turned them away. He passed completely on hiring Urban of Hungary and his troop of mercenary cannoneers. Within a few months, Mohammed II had hired Urban’s troops, and Bassilica, to assist him in attacking Constantinople. Having given the Byzantines first chance, the gunner accepted the sultan’s offer. Instead of defending the Christian city, his guns would instead batter down its walls.

By the end of the spring of 1452, the Turks had completed the fort that was to cover their army while they crossed the Bosphorus. By spring of 1453, Mohammed II was ready to besiege Constantinople. On April 6, every gun in the Muslim army began pummeling the city’s walls. Most of these were those cannons hired from Urban the Hungarian. After twelve days of steady bombardment, there was a narrow breach in one wall. Walls that had held out for a millennium were breached in less than two weeks by the cannon that Constantine XI had turned down. Hundreds of Turks attacked the small breach but were easily beaten off.

On May 6, the cannons created another breach where the Lycus River entered the city through the eastern wall. On the next day, the sultan threw 25,000 men into the attack, which was driven off after only three hours of intense fighting. The garrison did their best to repair the damage, but from this point they were stretched by the need to always keep men near the weakened areas.

Six days later, another breach was opened near the northern end of Constantinople’s great wall. The attack on that breach almost broke into the city. Only the timely reinforcement of the defenders by Constantine and his imperial guard saved Constantinople. The siege continued for weeks, with the valiant defenders thwarting an attempt to use a giant siege tower and tunnels to overcome the defenses. All this time, the cannon battered at the walls, attempting to create new breaches and reopen those that had been repaired. Ultimately, even the thick great wall was torn and battered.

After his largest siege tower was lost, some of the sultan’s generals began to council him to withdraw. But others encouraged the Turkish leader to give it one more try. If the general assault failed, they would withdraw. The cannon that Constantine XI had previously turned down had seriously weakened the great wall where the Lycus River entered the city. On May 29, Mohammed II threw everything into one final assault. Almost 20,000 Bashi-Bazouks, mercenaries who fought for loot, attacked first. They were driven off, but directly behind them came a second line of Turkish regulars who took up the attack on the weakened wall. They pushed at the partially blocked breaches and were driven off after only two hours of intense fighting. The defenders were exhausted and the great wall provided less and less protection. But before they could recover, a third wave of Turks attacked. Summoning their last reserves, the Christian defenders drove them away as well.

Unfortunately for the city, while almost every soldier was fighting near the Lycus breach in the center of the great wall, a few Turkish soldiers managed to rush through a small gate that had been left open elsewhere. They seized control of a small tower at the far north end of the wall and raised the sultan’s banner over it. While this really was just a minor threat, it appeared to be a disaster to the wall’s defenders. Their morale and determination plummeted as word spread among the defenders. Then the leader of the largest group of mercenaries was wounded and had to be carried from the wall. Exhausted men who had been fighting on adrenaline lost hope.

The sultan sent in his own elite troops, the Janissaries, who managed to gain control of the section of the eastern great wall from the Lycus to the next gate above it, the Adrianople Gate. Once the Janissaries had that gate open, tens of thousands of Turkish soldiers poured into Constantinople. Constantine XI Palaeologus, the last Byzantine emperor, died fighting in the streets.

The Turkish victory almost didn’t occur. Under pressure from his generals, if the last attack had failed, Mohammed II was ready to pack up and leave. Had the Byzantine emperor hired Urban the Hungarian and his cannon, the breaches that weakened the great wall would have never happened. Without those breaches, the sultan’s army would have found assaulting the walls of Byzantium an almost impossible task.

The effect of the fall of Constantinople on Europe was a surprising one. The subsequent monopoly prices charged by the Turkish merchants for the products and spices of the East inspired western Europe to search for another way to trade with the Orient. Within thirty years the Portuguese were traveling around Africa, and exactly forty years later, Ferdinand and Isabella financed Christopher Columbus’ first expedition. The fall of the city forced the beginning of the greatest period of exploration ever recorded. While Constantine XI’s mistake of not hiring Urban doomed Constantinople and brought about the end of the Byzantine empire, that same loss led to the great Age of Exploration.

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