The Siege of Constantinople

By Legion of Hell

The siege of Constantinople (April 2nd – May 29th 1453) marked the end of the old Byzantine Empire, and the rise of the Ottoman Turks.

State of the Byzantine Empire

In the 1,100 years of the Empire Constantinople had only been taken once in the Fourth Crusade in 1204. The crusaders had not intended to take the city from the beginning, but after the capture a Latin state was established, which was quite unstable. The Empire fell into a plethora of Greek successor states, most notably Trebizond, Epirus and Nicaea. The Greek states allied together to fight against the Latin establishments, but also fought against each other over the Byzantine throne. The Nicaean Greeks were the first to re-conquer Constantinople, taking it from the Latins in 1261. In the following two centuries the much weakened Byzantines were facing threats from the Latins, Serbians, Bulgarians and most importantly, the Ottoman Turks. By 1453 the empire consisted of the city of Constantinople itself and a portion of the Peloponnese centred on the fortress of Mystras. The Empire of Trebizond, a completely independent successor state formed after the Fourth Crusade also survived on the coast of the Black Sea.


When Sultan Murad II was succeeded by his son Mehmed II in early 1451 it was widely believed that he was to turn out an incapable ruler and pose no threat to the Christian possessions in the Balkans and the Aegean. This belief was reinforced when Mehmed’s friendly reassurances to envoys that were sent to him at the start of his reign. However Mehmed’s promise to respect Byzantine territorial integrity was nothing but a lie.

During the spring and summer of 1452 Mehmed who remembered that his great grandfather Bayezid I built a fortress on the Asian side of the Bosporus named Anadolu Hisan, built a second fortress on the European side, which was outside the walls of Constantinople, which would further increase Turkish influence on the straits. The new fortress was called Bogazkesen in Turkish, which means strait-cutter in English.

The Byzantines appealed to Western Europe for help, but fell on deaf ears. Ever since the excommunication of the Orthodox and Roman Catholic Churches in 1054 the Roman West had tried to reintegrate the East. It had been tried in Lyons in 1274, but anti-unionist forces, the population of Constantinople and the leadership of the Byzantine Church were bitterly divided over union. Ethnic hatred between the Latins and Greeks over the sack of Constantinople played a significant role, thus the attempt of Union failed and annoyed the Roman Catholic Church.

In the summer of 1452 when the fortress was built and the threat of invasion was imminent the Byzantine Emperor Constantine XI wrote to the Pope seeking help with the promise of implementing Union, which was declared valid by a half hearted imperial court on Tuesday 12th December 1452. Although Pope Nicholas V was eager to help he did not have the influence over Western Kings and Princes that the Byzantines thought he had. Also the Western kingdoms had been badly hit with the Hundred Years War between England & France, Spain was in the final stages of the Reconquista, internal fighting of the German Principalities along with Hungary and Poland’s defeat at the Battle of Varna in 1444 at the hands of the Ottomans. Although some troops were sent from the city states in Italy it was not enough to counterbalance Ottoman strength.

Strength of the Armies

The army defending Constantinople was small; it totaled up to seven thousand men, with two thousand of them being foreigners. The city walls spanned 20km, with the Theodosian walls 5.5km long, the sea walls along the Golden Horn 7km long and sea walls along the Sea of Marmara. The walls were the strongest set of fortified in existence at this time. The walls had been repaired under John VIII and were in fairly good shape, with the defenders fairly well equipped. They also had a naval fleet of 26 ships: five from Genoa, five from Venice, three from Venetian Crete, one from Ancona, one from Spain, and one from France and ten, which were Byzantine.

The Ottomans on the other hand had a much larger force. It was thought to number between one hundred thousand men, including twenty thousand Janissaries. However witnesses of the siege who tended to exaggerate the power of the Sultan gave much higher figures. Nicolo Barbaro put it at one hundred sixty thousand, the Florentine merchant Jacopo Tedaldi and the Great Logothete George Sphrantzes put it at two hundred thousand, while the Cardinal Isidore of Kiev and the Archbishop of Mytilene Leonardo Di Chio put it at three hundred thousand!

Mehmed also had a naval fleet which was tasked to besiege the city from the sea. Again the reports about the strength of the Ottoman fleet were exaggerated as Tedaldi put it at a hundred ships, Barbaro at one hundred forty five ships, Ubertino Pusculo at two hundred two hundred fifty ships (Isidore of Kiev and Leonardo Di Chio at four hundred and thirty. A realistic report puts the total at one hundred twenty five of which six were large galleys, ten ordinary galleys, fifteen smaller galleys, seventy five large rowing boats, and twenty horse-transports.

Equipment and Strategy

Before the siege, the Ottomans were known to have the ability to cast medium sized cannon, but nothing near the range of some pieces they were able to field. Instrumental to this Ottoman advancement in arms production was a man named Orban who was either German or Hungarian and a mysterious figure. He immediately tried to use his skills to try and find a way to break down the walls of Constantinople.

Orban guaranteed Mehmed that he could produce cannons that were powerful enough to break the walls. Orban worked hard, finally making the cannon which could break the walls of Constantinople. It was called the Great Turkish Bombard and was twenty seven feet long, large enough for a man to crawl into. The bombard could fire a 1200lb (544kg) cannon ball as far as a mile. However it did have many drawbacks. It took three hours to reload, the cannon balls were in short supply and the cannon is said to have collapsed under its own recoil after six weeks (which is disputed). Having establishing a foundry one hundred fifty miles away Mehmed had to undergo the painstaking process of transporting the massive pieces of artillery. Orban’s giant cannon was said to have been carried by sixty oxen and over four hundred men.


Mehmed planned to attack the Theodosian Walls, a series of ditches and walls which protected an attack from the West and the only place not surrounded by water. His army encamped around the city on April 2nd 1453. Three days later as Mehmed arrived with the last of the troops the defenders of Constantinople took up their positions.

As there were insufficient numbers to fully occupy every wall in the city, Emperor Constantine XI decided only the outer walls would be manned. Constantine and the Greek troops were stationed at the Mesoteichon, the middle section of the land walls, where there were crossed by the river Lycus. This section was considered the most weakest of the walls and where an attack was most likely. Giovanni Giustiniani, an Italian specialist on defending wall cities who brought over seven hundred men from Genoa was placed north of Constantine at the Charisian Gate and the Myriandron.

Minotto and his Venetians were stationed in the Blachernae palace, together with Teodoro Caristo, the Langasco brothers, and Archbishop Leonardo di Chio. To the left of the emperor, further south, were the commanders Cataneo, with Genoese troops, and Theophilus Palaeologus, who guarded the Pegae Gate with Greek soldiers. The section of the land walls from the Pegae Gate to the Golden Gate, which was guarded by a Genoese solider called Manuel, was defended by the Venetian Filippo Contarini, while Demetrius Cantacuzenus had taken position on the southern part of the Theodosian wall.

The sea walls were manned more sparsely, with Jacobo Contarini at Stoudion, a makeshift defense force of Greek monks to his left hand, and prince Orhan at the Harbour of Eleutherius. Péré Julia was stationed at the Great Palace with Genoese troops, while Cardinal Isidore of Kiev guarded the tip of the peninsula near the boom. The sea walls at the southern shore of the Golden Horn were defended by Venetian and Genoese sailors under Gabriele Trevisano.

Reserves were in the form of two tactical groups which were kept behind in the city, one in the Petra district just behind the land walls and one near the Church of the Holy Apostles, under the command of Lucas Notaras and Nicephorus Palaeologus, respectively. The Genoese Alviso Diedo commanded the ships in the harbour. Although the Byzantines also had cannons, they were much smaller than those of the Ottomans and the recoil tended to damage their own walls.

The bulk of the Ottoman army was encamped south of the Golden Horn. The regular European troops, who were stretched along the entire length of the walls, were commanded by Karadja Pasha. The regular Anatolian troops commanded by Ishak Pasha were stationed south of the Lycus down to the Sea Of Marmora. Mehmed erected his red and gold tent near the Mesoteichon, where the artillery and elite units such as the Janissaries were placed.

The irregular Bashi-bazouks were spread out behind the front lines. Other troops under Zaganos Pasha were stationed north of the Golden Horn. As the Ottoman army was spread quite far communication was maintained by a road which had been constructed over the marshy head of the Horn.

The Siege Begins

Mehmed sent out his best troops to reduce the remaining Byzantine stronghold outside the city of Constantinople. The fortress of Therapia on the Bosporus and a small castle at the village of Studius were taken within a few days. The Princes Islands were taken by the Ottoman navy, commanded by Admiral Baltoghlu. Mehmed’s massive cannon fired on the walls for weeks, but due to its slow rate of fire and inaccuracy the Byzantines were able to repair most of the damage after the cannon was fired, limiting the cannons effect.

Naval Front

Meanwhile the Ottoman naval fleet could not enter the Golden Horn, as the Byzantines had laid barrier along the entrance. What furthered angered the Sultan was that even though the naval fleet were tasked to prevent any ships entering the harbour a small flotilla of four Christian ships on the 20th April managed to slip in after heavy fighting , causing morale to increase among the defenders. The Sultan spared the Admiral’s life after his subordinates testified to the Admiral’s brave efforts during the battle.

To counter the barriers the Byzantines set up Mehmed ordered the construction of greased logs across Galata on the north side of the Golden Horn and rolled his ships across on the 22nd April. This seriously threatened the flow of supplies from the Genovese ships from the supposedly neutral colony of Pera and demoralized the Byzantine defenders. On the night of the 28th April an attempt was made to destroy the Ottoman fleet placed in the Golden Horn by using fire ships, but the Ottomans had been warned in advance and forced them to retreat with heavy losses. From then on Constantine was forced to divert troops to the Golden Horn walls, causing other sections of the walls to weaken.

Mining the Walls

The Turks had many numerous frontal assaults on the land walls, but were always repelled with heavy losses. From mid-May to the 25th May the Ottomans forced to breach the walls by building underground tunnels to try and mine them. Many of the sappers were Serbians sent from Novo Brdo by the Serbian Despot. They were placed under the command of Zaganos Pasha. However the Byzantines employed an engineer named Johannes Grant (who said to be German but was probably Scottish) who had countermines dug, allowing Byzantine troops to enter the mines and kill the sappers. The Byzantines first intercepted the Serbian tunnel on the night of the 16th May. Further tunneling efforts were interrupted on the 21st, 23rd and 25th May, destroying them by fierce hand-to-hand combat or Greek fire. On the 23rd May the Byzantines captured and tortured two Turkish officers, who revealed the location of the tunnels, which were then destroyed.

Dangerous Signs

Mehmed offered to lift the siege if they gave him the city. When it was refused Mehmed planned to overpower the walls through sheer force, knowing that the Byzantine defenders would be worn out by the sheer Ottoman numbers.

On May 22nd the moon, symbol of Constantinople, rose in dark eclipse, fulfilling a prophecy on the city’s demise. Four days later, the whole city was blotted out by a thick fog, a condition unknown in that part of the world in May. When the fog lifted that evening, a strange light was seen playing about the dome of the Hagia Sophia, and from the city walls lights were seen in the countryside to the West, far behind the Turkish camp. The light around the dome was interpreted by some as the Holy Spirit departing from the Cathedral, while there was a distant hope that the lights were the campfires of the troops of John Hunyadi who had come to relieve the city.

The following day a small Venetian ship of twelve entered the Capital and reported to the Emperor that no Venetian relief fleet was on its way after having searched the Aegean. Nonetheless the Emperor was able to receive the aid of the twelve in the defense of the city.

Mehmed called a war council on the 26th feeling that the siege had gone on for long enough. For thirty six hours the Ottomans prepared by mobilizing their manpower for an all-out assault. Meanwhile while the Ottomans were mobilizing large scale prayers were held in Constantinople.

Shortly after midnight on the 28th the Ottoman attack began.

Final Assault

The first wave was the auxiliaries or azabs who were poorly trained and equipped, with the task to kill as much defenders as possible. They were easily dealt with by the defenders. The second wave was the Anatolians, who were focused on the section of the Blachemae walls on the northwest part of the city, which had been partially damaged by the cannons.

The Ottomans managed to break through the walls, but were quickly repulsed by the Christian defenders. The defenders also managed to hold off a third attack from the Sultan’s elite Janissaries. But tragedy struck when the Genoese general Giovanni Giustiniani was grievously wounded in the attack and his evacuation caused panic in the ranks. Giustiniani was evacuated to Chios where he died of his wounds a few days later.

With the Genoese troops retreating into the city towards the harbor, Constantine and his men, now left to their own devices held off the defenders for a while. At this point some historians suggest that the Kerkoporta gate in the Blachemae section was left unlocked, and the Ottomans soon seized on this mistake, by rushing in. At this time the defenders were being overwhelmed in several points of Constantine’s section.

When Turkish flags were seen flying over the Kerkoporta gate panic ensued and the defence collapsed. It’s said that Constantine threw away his purple regalia (cape?) and led the final charge, rushing towards the oncoming Ottomans, dying in the raging battle along the streets, although his ultimate fate remains unknown. The Byzantine casualties during the siege were four thousand military dead and ten thousand civilian dead, while the Ottoman casualties were unknown.


The fortress of Mystras, where Constantine’s brothers Thomas and Demetrius ruled, knowing that Mehmed would eventually invade them as well, held out until 1460. Long before the fall of Constantinople, Demetrius had fought for the throne with Thomas, Constantine, and their other brothers John and Theodore. Thomas escaped to Rome when the Ottomans invaded Morea while Demetrius expected to rule a puppet state, but instead was imprisoned and remained there for the rest of his life. In Rome, Thomas and his family received some monetary support from the Pope and other Western rulers as Byzantine emperor in exile, until 1503. In 1461 the independent Byzantine state in Trebizond fell to Mehmed.

Scholars consider the Fall of Constantinople as a key event ending the middle Ages and starting the Renaissance because of the end of the old religious order in Europe and the use of cannon and gunpowder. The fall of Constantinople and general encroachment of the Turks in that region also severed the main overland trade link between Europe and Asia, and as a result more Europeans began to seriously consider the possibility of reaching Asia by sea.


Sir Steven Runciman – The Fall of Constantinople
Phrantzes, the fall of the Byzantine Empire
Various internet sources