How Istanbul Was Conquered: The History of the Conquest of Istanbul



The Conquest of Istanbul was carried out on May 29, 1453, by the Ottoman sultan of the period, 21-year-old Mehmet II, and the Janissary Army under his command. With the conquest of Istanbul, the Byzantine Empire, which was the continuation of the 1500-year-old Roman Empire, fell apart and migration to the Christian world started in the city. Conquest of Istanbul is also the day when the Middle Ages ends and the New Age begins. The conquest of Istanbul is also of great importance in terms of military history. From ancient times until that time, city walls and city walls were the greatest means of defense that protected cities against the occupation. However, the Ottoman Army, using black powder during the war, managed to destroy the city walls.

With the siege of the Ottoman Empire, the huge cannons specially designed by the Sultan were launched. Byzantine attempts to repair the breaches that were opened when the cannon shots began to make breaches in the city walls at night. Suggesting that Istanbul cannot be taken without entering the Golden Horn, Sultan II. Mehmed thinks that the artilleries that are fired should be developed and launched to their target with a curved landing by inclining in the air and plans and draws accordingly. A wide road is opened from Dolmabahçe to the ridges of Beyoğlu is laid secretly along the way. Ships are launched overnight by walking from the land. II Mehmed orders a major offensive on 29 May. On Tuesday, 29 May 1453, Istanbul surrenders to the Ottoman troops.



After two attacks that started on the night of May 29 and continued until close to morning, a general attack started on Tuesday, May 29; The real result was the gap opened between Topkapı and Edirnekapısı and the central branch where the peddler was located was attacking here. The first general attack lasted two hours, followed by the second general attack lasted an hour and a half, and no result was obtained yet; the defenders also worked hard, killing those who climbed the stairs and climbed the walls with Grojuva fire and other means; No success was achieved in attacks on other arms.

Thereupon, the janissaries and reserve forces in the central branch were put forward as the last trump card. This time the pastor himself was with the janissaries; the emperor was also on this front; Meanwhile, Jüstinyani, the commander-in-chief who defended the walls with great determination, was injured in his hand and arm, and he withdrew by abandoning the defense, despite the emperor’s request, because he was more likely to lose blood. During this attack, the janissaries went as far as the ditch. The Pâdishah stopped them there and sent them to the attack under the auspices of the arrows and archers; the janissaries crossed the moat and stood against it.

Emperor Constantine XI defended the city with great determination despite many troubles and betrayals, and although he was offered to escape by sea, he refused and died near his soldier and for the defense of his country. Constantine was between forty-nine and fifty years old at his death. The number of prisoners taken after the conquest of Istanbul was about fifty thousand.

How Istanbul Was Conquered I: Siege Preparations


With the Ottoman expansion of his territory in the region, when Mehmet II took the throne, Istanbul was surrounded. The Byzantine Empire tightened chains to the Golden Horn during the siege and reinforced its navy. Another means of defense of Byzantium was the Grejuva. The Grejuva was not extinguished in water and was to be used effectively in both land and sea warfare. In order not to suffer during the siege, provisions, and ammunition storages were reinforced; The number of guards and soldiers from various countries was increased and the city walls were strengthened. Along with three galleys, 200 soldiers and ammunition were sent by the Papacy, and 30 ships were reported to be prepared for the expedition.

In January 1453, together with two ships, 700 soldiers under the command of the Genoese commander Giovanni Giustiniani came to help. Guistiniani was appointed commander in chief by the emperor Constantine. If the battle ended in Byzantine victory, the island of Limnos would be given to Giustiniani. The main element in the defense plan of Byzantium was the walls of Istanbul. The walls of Istanbul were not designed only against an attack from the land; The seaside of the city was also completely surrounded by walls. Today, the area known as Sarayburnu was completely isolated from the sea.



Heavy cannons were built to be used by the Ottomans during the siege. The “Shahi” ball, which was built by an engineer named Urban, who was kidnapped by sewers from Byzantine dungeons, was one of them, its single shot was around 550 kilograms and the length of the ball was 8 meters and its circumference was 2.5 meters. In order to completely disconnect Istanbul from the sea and to prevent any aid from the city during the siege, II. Mehmet found it necessary to build the Rumeli Fortress opposite Anadolu Hisarı.

There are various opinions about the size of the Ottoman army, according to Hammer it was 250,000, according to Barbaro 160,000, and according to Sfrantzes and Dukas 200,000 soldiers. The Ottoman Navy was also prepared to support the sea during the siege; There are different opinions about the existence of the fleet given under the command of Baltaoğlu Süleyman Pasha; Dukas says 300 and Georgios Francis says 160. Before the siege, some castles and towns around the city were captured by 10,000 soldiers under the command of Karaca Pasha.

On April 6, 1453, the Ottoman land army was positioned in front of the city walls, extending from the Golden Horn to the Marmara. The Ottoman army destroyed the suburbs around the city before the attack. The weakest parts of the walls were identified in order to choose where the guns would be deployed. Two days after the deployment of the cannons, the Ottoman Navy under the command of Baltaoğlu Süleyman Pasha captured Prinkipos (Büyükada) and Antigoni (Burgaz Island) and a Byzantine castle in Tarabya.



After the deployment of the balls, II. Mehmet sent his vizier Veli Mahmud Pasha to Emperor Constantine and demanded the surrender of the city. Constantine said he was sworn to protect the city, but that he could pay taxes if asked. Ottoman artillery fire began on April 12, 1453. According to many sources, these cannons, which were seen as powerful for their period, were making a great noise and demoralizing the defenders of the city. Ottoman cannons were loaded in about two hours, so artillery fire was not frequent. II. Mehmet wanted the cannons to be fired more frequently, and as a result, a cannon exploded, the master Urban and those around him died.

Although a repair shop was established in the camp to maintain the cannons, according to the historian Hammer, the shattered ball could not be repaired due to Urban’s death. Ottoman artillery fire continued until April 18. On April 18, at the point where the Ottoman central army was located, a breach was opened in the first and second walls on the sides of Bayrampaşa Stream. By order of Mehmet II, the ditch in front of the walls was filled with stones and sandbags. The Ottoman army launched a night attack. War towers were built by the order of Mehmet II to support the attack.

However, the Ottomans did not get any results from the night attack; the marching towers caught fire with Grejuvas, and the Ottoman soldiers who managed to climb the walls faced stubborn defense. In the same days, the Ottomans also launched a sea offensive; The Ottoman navy, which collapsed in front of the Golden Horn on April 15, 1453, could not break the chain due to the defense of Byzantine and allied navies and had to retreat. The failure of both attacks raised morale on the Byzantine side.

How Istanbul Was Conquered II: Sea Battle


On April 20, the aid fleet, consisting of a Byzantine and three Genoese galleons commanded by captain Flantanellas, approached Istanbul. II. Mehmet sent Baltaoğlu Süleyman Bey to the aid fleet with 18 ships. The aid fleet, with the wind behind it, was advancing faster and the Ottoman ships could not dock. Four galleons remained motionless when the wind ceased off the coast of the area known today as Yeşilköy; Ottoman ships reached the galleons by rowing. Due to the prolongation of the fighting, the Ottoman ships that came from behind also caught up, and the Genoese-Byzantine fleet of four ships surrounded about 150 Ottoman ships. However, the superiority could not be established due to the galleons being higher than the Ottoman galleys and the inexperience of the crews on the foremost Ottoman ships.

Baltaoğlu Süleyman Bey, who saw heavy casualties, ordered the navy to withdraw. Having seen defeat from a dominant hill, II. Mehmet got angry and tried to preach his orders to Baltaoğlu Süleyman by riding his horse into the sea. However, the Ottoman navy was defeated, the aid fleet continued on its way and when the darkness came, the chain that closed the Golden Horn was loosened, and the help of two Venetian ships took shelter in the harbor and successfully delivered its aid to Constantinople. The next day, Mehmet II went to the navy command with ten thousand horsemen to account for the defeat. The angry sultan who wanted to execute Baltaoğlu Süleyman Bey gave up execution as a result of the begging of other statesmen, but he dismissed Baltaoğlu by beating him with his mace; Çalıbeyoğlu Hamza Bey was brought to the vacant captain.



After the failure of the attacks on the city, the galleons that brought aid broke through the Ottoman navy and II. Mehmet held meetings with statesmen and commanders. Repeating that European states would come to help at the meeting, Çandarlı Halil Pasha suggested that the siege be lifted and that Byzantium be subjected to 70,000 Ducat gold tax. However, other people, including Mehmet II’s brother-in-law Zağanos Pasha and his teacher Molla Gürani objected to this proposal. Despite this, nobody could make any proposals about how to enter the Golden Horn at the meeting. 14 years before Mehmet ascended the throne, Venetian commander Gattamelata took his ships from the Adige to Lake Garda by land. It is estimated that this event is taken as an example in the operation of ships from land.

First, Zağanos Pasha was ordered to build a bridge over the Golden Horn to establish a land connection between Galata and Constantinople walls. However, it was thought that this bridge would be vulnerable to Byzantine and allied ships in the Golden Horn. Thereupon II. Mehmet ordered the Ottoman navy in front of the Diplonsion (today’s Beşiktaş) to slide in front of the Galata walls and land on the Golden Horn. Additionally, cannons were placed on the dominant hills around Galata to hit the Golden Horn walls and the navy on the Golden Horn. The distance the ships would pass was 2 to 4 kilometers and it was forested; The trees on the route were cut down and then the trees were fixed on the soil by lubricating with the olive oil given by the Genoese.

The Genoese followed a policy of balance throughout the war and helped both the Byzantine and the Ottoman sides. Before the ships were executed, Ottoman artillery deployed on Galata sides bombarded the ships in the Golden Horn. The ships were sailed on the night of April 21-22 so that the Byzantines would not notice. Meanwhile, in a diverting way, a large breach was opened around St Romanos Gate. Those in the city that night were busy closing this gap. In the morning, 72 Ottoman warships were successfully landed and the chain that closed the Golden Horn was dysfunctional. The Ottomans started the construction of the wooden bridge, the second stage of the plan. On April 24, a galley of Giustiniani approached to burn the ships but was sunk by Ottoman artillery.



After the incident, those on the Byzantine side gathered at St Maria Church and found it necessary to make a second attack and burn the ships. The attack was to be carried out at night under the command of Venetian captain Jacomo Coco. Galata Genoese, who postponed the attack for one day on the pretext of preparing the ships for the attack, took advantage of the time they had saved and conveyed the plan secretly to Mehmet II. Learning of the plan, II Mehmet ordered the ships in the Golden Horn to be reinforced and two more guns to be placed on the shores. On the night of April 28, two or three ships loaded with Grejuvas under the command of Jacomo Coco approached the Ottoman ships. But the Ottoman navy, aware of the attack, opened fire; Coco’s ship was sunk.

The other galley under the command of Cabriel Trivixan did not notice what was happening to Coco’s ship due to the noise of the guns and continued to move forward. Ottoman artillery hit this galley as well; a hole was drilled in the hull, but the galley was prevented from getting water, as the two crews squeezed their capes into the hole. On the other hand, a ship of the Ottomans was burned and the captured sailors were killed, visible from the city. In retaliation, the Byzantines executed 260 prisoners in their hands and put their severed heads on the walls.

How Istanbul Was Conquered III: Artillery Fires


After the Ottoman ships fend off the Byzantine counterattacks on the Golden Horn, the artillery deployed in Galata began to bomb the walls along with the ships in the Golden Horn. Thereupon, the Byzantines had to move soldiers to the Golden Horn walls. Still, the Ottoman artillery could not demolish the walls due to the long distance. Of the 150 shots, only 1 was hit and a woman died. Relieved that the Golden Horn walls were not damaged, the Byzantines placed two cannons on the walls of the Golden Horn on May 3 to protect their ships under heavy fire. As a result of the fire opened, two Ottoman ships were sunk. The answer of the Ottomans was to bring these two cannons under fire by bringing three cannons to the opposite shore. Despite the ongoing conflict day and night, neither side could destroy each other’s cannons.

While the mutual bombardment continued on the Golden Horn, the walls around St Romanos were also being bombed. The increasing number of walking towers were higher than the city walls and small cannons were placed in them, and the Ottoman soldiers prevented the gaps opened by these towers. The ditches filled with fragments falling from the walls gave the Ottoman army the opportunity to attack. Byzantine defense continued to inflict losses on the Ottomans; four moving towers were burned. Considering that the walls were sufficiently worn, Mehmet II launched an attack on the evening of May 6. But no result was achieved and the army, which suffered heavy losses, retreated. After this attack, the most worn part of the walls, St. Romanos was reinforced with some 400 Venetian sailors.



After that, artillery fire concentrated on the walls between Kaligaria Gate (Eğri Kapı) and Blakernai Palace. The Ottoman army, which entered the breaches opened on May 12, was repelled as a result of the training of Byzantine reserves, although they prevailed at first. Then, another attack was carried out; In this too, the Ottomans withdrew without getting results due to the Byzantine force of a thousand people coming to help from Caligari. On the morning of May 19, the Ottoman army brought a walking tower higher than the city walls near the Adrianapolis Gate. It consisted of a wooden skeleton covered with layers of ox/camel skin and the gaps of the skeleton were filled with soil, thanks to this tower, where arrows and small cannonballs could not damage, the ditches were filled with earth while shooting arrows at the soldiers on the wall.

On the same day, the Ottoman army built a bridge of tied barrels where the Golden Horn contracted; In order not to be destroyed by a fire that the Byzantines could open, it was not extended to the Kynegos Gate on the Golden Horn walls. The Byzantine side had to deploy soldiers on the Golden Horn walls despite the possibility of extending this unfinished bridge to the Kynegos Gate. On May 21st, the entire Ottoman fleet came to the Golden Horn, the townspeople, who thought that the general attack would begin, panicked, and bells were ringed in churches; However, as there was no land attack, the Ottoman navy returned a few hours later. According to the Venetian doctor Barbaro, who was in the city during the siege, the walls were being bombed every day; The artillery he described was throwing a 544-pound shot, and each shot caused panic in the city.



On the morning of May 16, the guards, hearing voices from underground around the Kaligaria Gate, noticed that the Ottoman sewers were digging a tunnel and began digging a tunnel themselves to stop it. When the two tunnels met in a short time, the underground war started; The fire deliberately started by the Byzantine sewers who were in charge of destroying the tunnel of the Ottomans at all costs caused the death of the Ottoman sewers and the collapse of both tunnels. On May 21, Ottoman sewers opened a second tunnel around the Kaligaria Gate, which lacked watchtowers, and it was also noticed by those in the city; As in the previous tunnel, the Ottoman sewers, who predicted that the Byzantine sewers would start a fire again, set their tunnels on fire without giving them a chance, causing the death of the Byzantine sewers along with them.

The next day, another tunnel was discovered in the same place; With the hot oil spilled by the guards, the sewers were killed and the tunnel set on fire, the same day an as yet undiscovered Ottoman tunnel collapsed. Engineer Jean Grant, who was among the defenders of the city, started to work to find out if there were other tunnels, and as we entered the last week of the siege, several more Ottoman tunnels were discovered every day; On May 23-24-25, other tunnels were found in the same place. The tunnel noticed on 25 May reached under the walls; If destroyed, the walls could collapse; Byzantine sewers were content to wall the tunnel.

How Istanbul Was Conquered IV: The Final Offensive


After the fleet landed on the Golden Horn, the famine that started in the city, the underground wars, and the towering high above the walls, the Ottoman army had begun to prepare for the final attack. On 23 or 24 May II. Mehmet sent his brother-in-law İsfendiyaroğlu Kasım Bey to Emperor Constantine as an ambassador. It was stated that if they surrendered, Constantine and his family could safely go wherever they wanted, the lives and properties of the people would not be touched, and lastly, friendly relations would be established with the Paleologos dynasty, but if they did not surrender, the emperor and other nobles would be killed, the people of the city would be captured, and the army would be allowed to plunder.



The emperor refused to surrender the city but stated that he was ready to pay taxes. Despite the concerns of Grand Vizier Çandarlı Halil Pasha, it was decided to continue the siege and to make the last attack on 29 May. The decision and day of the attack were announced to the Ottoman army; If the city was conquered, it was declared by the sultan that all soldiers had the right to plunder the city for three days. In addition, the sultan declared that he would award the first soldier to rise on the walls, but also execute those who escaped from the war; After the pillage permit was issued, festivities started in the Ottoman army and tents and ships were illuminated; Takbir voices were rising so that those in the city could hear.

Sultan Mehmet divided his army into three groups; the first group consisted of elders and Christians, the second group of Muslim peasants and torments who joined the army, and the third group of janissaries. It is recorded that each group consists of approximately 50 thousand soldiers. Most of the army was in front of the severely damaged St Romanos Gate. Emperors Constantine and Giustiniani were also waiting with their troops to defend this line. On Tuesday, May 29, the Ottoman army prayed before sunrise and the Mehter team began to play the assault anthem. The primary task of the first group of the elderly and Christians was to move the stairs to the walls.

The battle started before sunrise, but the stairs erected on the walls were immediately toppled by the Byzantine soldiers, and the soldiers approaching the walls were killed by throwing stones and arrows. The attack of this group lasted two hours. This group, most of which was destroyed, started to flee towards the camp. But the order given by II Mehmet the day before was executed; The fleeing soldiers were slaughtered and forced to return to the walls. The turn was in the second group consisting of the main combat soldiers, and this group’s attack started. The attack was increasingly concentrated around St Romanos, but the soldiers of the second group could not climb the walls or erect the stairs.



Byzantine soldiers repelled all attacks using hot oil, Grejuva, arrows, and stones. The second group was also exhausted and this had a positive effect on the morale of the Byzantine forces; After an hour and a half of war, some soldiers from the second group also started to flee. Those who escaped from the war also faced the executions of their commanders and Sultan Mehmet II punished a few fugitives with his mace. Mehmet II approached the walls with his janissaries, the last group remaining in his hands. Byzantine troops were tired now, vigorous and experienced janissaries reached the walls without breaking their ranks; When the Kerkoporta Gate, which was opened on the orders of Constantine for the counterattack the night before, allowed about fifty Ottoman soldiers to enter, the morale of the Byzantine soldiers deteriorated.

At that time, the great Ottoman cannon was fired and a passage was opened for the Janissaries, and the clash of the Janissaries and Byzantine soldiers began in the dust cloud. The Ottoman soldiers who managed to enter the watchtower were destroyed and the Byzantine soldiers, who saw that they repel the Janissaries, began to enjoy the victory, but the Ottoman cannon fired again; The offensive of the remaining Ottoman troops had begun. The first wall, which did not have any resistance, was captured by the Ottomans, and the janissaries, who secured this place with the support of the torments, started the attack on the second wall with all their might.



Both walls were in ruins and fighting was ongoing. With the effect of the defeat, the Piya Gate in the south also fell and the pillage of the Ottoman soldiers began. The weight of the army was moving towards the center of the city, the wealth there was greater, and the bannermen wanted to plant the Ottoman flags as soon as possible. By noon, the city had fallen and loot started, but the resistance continued in the walls of the Golden Horn, the bastions of Vasileos, Leon, Alexius; Although the Golden Horn walls were dropped later, the three bastions continued to resist. These three bastions defended by Cretan sailors surrendered, and the sailors were given permission by Mehmet II to return to their homes.

Mehmet II, with his viziers and commanders, entered the city through St Romanos Gate (Topkapı). Coming in front of Hagia Sophia II. Mehmet fell prostrate and kissed the ground and asked the crowd who took refuge in the church to go out, saying that they would only be made slaves; their souls were left untouched. It is mentioned in historical sources that he examined the mosaics and valuable marbles in Hagia Sophia. Meanwhile, when he saw a soldier trying to dismantle the marble, he reacted and said that the buildings in the city were his property. Despite the three-day pillage he had given to the soldiers before the attack, he ordered the looting to be finished immediately and those who disobeyed to be executed.

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Savaş Ateş

I'm a software engineer. I love Istanbul. I have been to 10 different countries. Istanbul is in the top 3 cities. I like to play soccer too :)

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