Constantinople was one of the largest and wealthiest cities in Europe. Throughout the medieval ages, it was renowned for its power and splendour. Covetous of its riches, many eastern and western powers sought the city for themselves. But despite countless attacks, Constantinople stood firm and survived for over 1,000 years. It fell once in 1204 due to disunity which allowed the enemy to exploit a weakness in its defences. Only the Ottomans managed to conquer Constantinople in 1453. They did so by ushering in a new age of warfare; the age of gunpowder. In this article I shall outline the reasons that made Constantinople so difficult to take.

The natural advantages of Constantinople

Constantinople was favoured with natural advantages that made it difficult to conquer. It was located on an elevated rocky peninsula, surrounded by the sea on three sides. To the north lay the estuary known as the Golden Horn. To the east lay the straits known as the Bosporus. The Bosporus connected the Black Sea further north with the Sea of Marmara. Finally, on the southern shore of Constantinople, lay the Sea of Marmara itself. ¹

Attacking Constantinople by sea was difficult. The strong currents of the Bosporus endangered hostile fleets without shelter. Meanwhile the Golden Horn served as a perfect harbour for the Byzantines in war and peace. During times of war, it sheltered friendly ships. At the same time it allowed Constantinople to receive supplies by sea to withstand long sieges. ²

The only landward route to the city lay on its western side. Countless hosts of bloodthirsty enemies approached from this front in the hopes of taking the city. But the land walls of Constantinople continually thwarted their efforts until 1453. In 1453, the Ottomans, relying heavily on gunpowder and cannons managed to breach the ancient walls and overwhelmed the defenders. ³

The land walls of Constantinople

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The land walls of Constantinople protected the western side of the city from land based attacks. Known as the Theodosian walls, it was situated 1.5km west of the original Constantinian walls. The Theodosian walls, built around 412, stretched 6km. ⁴

The first line of defence was a moat that ran along the lands walls. It was about 20 metres wide and 7 metres deep. A stockade on the side of the city reinforced the moat. If enemy troops managed to cross the moat under heavy arrow fire, they came to the land walls of Constantinople. ⁵

Around 90 square or octagonal towers lined the walls every 70-75 meters. These towers provided additional defences and a position to mount catapults on. A low outer wall about 9 metres in height provided the second layer of defence. Enemy troops that made it past the outer wall and accompanying projectile fire would find themselves obstructed by the last line of defence; an inner wall. The formidable inner wall was around 12 metres high and about 6 metres thick. Adequately manned, the land walls of Constantinople were impregnable. ⁶

3 weaknesses of the land walls

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Despite its power, the land walls had some weaknesses which enemies could exploit. Firstly, there were the pipes and aqueducts that supplied the city with water. In times of war, the defenders cut off these supplies and survived on water collected by the cisterns. But the enemy could still enter Constantinople via the aqueducts if the defenders were not prepared. ⁷

Secondly, the Blachernae area where the land walls met the sea walls, tended to be more vulnerable. Situated on a slope, it was not part of the original walls and tended to jut out. As a result, it lacked an outer wall and a moat. This made it a source of frequent attacks during sieges. The Byzantines remedied this weakness by strengthening its defences in the 12th century. ⁸

Lastly, there was a vulnerable area between the Gate of Adrianople and the Gate of St Romanus known as the Mesoteichion. Due to the terrain, the walls had to accommodate the valley of the River Lykos. This gave the attackers the advantage of higher ground from which they could bombard the defenders. The moat also tended to be shallower in this area. Many attacks focused on this area of the walls. But all these vulnerabilities never delivered the city into the hands of attackers. ⁹

The sea walls of Constantinople

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Sea walls, not as powerfully built as the land walls, lined the sea facing sides of the city. Any naval attack on the city was difficult due to the hazardous sea currents. To be successful by sea, the enemy had to seize the Golden Horn on the northern side of the city. But a 300m long iron chain and the Byzantine navy blocked the Golden Horn in times of war. Supplementing these naval defences was the Byzantine secret weapon; Greek fire. Only once during the 4th Crusade did Constantinople fall because of its sea walls. ¹⁰

The Byzantine secret weapon; Greek fire

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A key factor in the defence of Constantinople was the secret weapon; Greek fire. Greek fire was a liquid flame projected through siphons that was capable of burning even on water. Not only were its effects devastating, it also dampened the morale of enemies who had never seen this fearsome weapon before. Many key naval engagements and sieges may have been lost without Greek fire. Unfortunately, the exact composition of Greek fire was a state secret which is unknown. ¹¹

The capacity of Constantinople to withstand sieges

Because Constantinople was an imperial capital, it had to have the capacity to withstand long sieges. Water was essential to the survival of the city in times of war and peace. But Constantinople lacked drinking water. The Byzantines addressed this issue through two means. Firstly, aqueducts from Thrace supplied water to the city. Secondly, vast cisterns collected rainwater and stored it for public use. ¹²

Next, there was the issue of food supplies. Most of its residents had their own gardens to grow vegetables. Due to its strategic location, food and other necessities could reach Constantinople by land and sea. In the meantime, the imperial granaries stored a reserve of grain in case of an emergency. All these measures contributed to the ability of Constantinople to withstand long sieges which slowly whittled down its attackers through attrition. ¹³

Finally, inefficient management of waste during a siege could be fatal to the health of the defenders. Luckily, Constantinople also had an underground drainage system that carried wastewater out of the city. ¹⁴

The importance of the human element

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Finally, there was the defenders; the human element. Most sieges tended to be long. As the months dragged on and the conditions worsened, hope and faith were all that sustained the defenders. It was the underlying self-confidence of the Byzantines that enabled them to fight on in the most adverse of circumstances. ¹⁵

Firstly, the Byzantines believed in the power of their defences, technology and the divine leadership of their emperor. Secondly, the Byzantines believed that Constantinople had divine protection from the Virgin Mary and the other precious relics stored in the city. By displaying the icon of the Virgin Mary during a siege, the morale of the Byzantine defenders would receive a vital boost. Lastly, they believed that God decided who would win and lose. Through sincere devotion and prayers, God would continue to protect them. ¹⁶

Luck also played a huge part in the defence of Constantinople. During the reign of the emperor Heraclius, Constantinople nearly fell to a combined attack by the Avars, Slavs and Persians in 626. But thanks to his prudence and daring, he saved Constantinople by attacking the Persians in their homelands. Then, in 717, the Byzantines were powerless to prevent the mighty Arab army from marching through the empire to place Constantinople under siege. Here, in their imperial city, the Byzantines made their final stand. This time, the emperor Leo III led the defence of Constantinople. He skilfully combined diplomacy, military strategies and Greek fire to drive off the Arab army. ¹⁷

Reflections of the Vizier

Conquering Constantinople during its heyday was a daunting task. The geographical advantages, fortifications, technology, bountiful supplies and dauntlessness of its defenders made the city almost impregnable. But this never stopped those who craved its immense riches from trying. During many critical moments in their history, the Byzantines were also lucky to have skilled and valorous emperors to defend the empire against their enemies. All these factors combined to make Constantinople one of the most difficult cities to conquer in history.

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References

Rautman, Marcus. Daily Life in the Byzantine Empire. Connecticut: Greenwood Press, 2006.

Harris, Jonathan. Constantinople: Capital of Byzantium. New York: Continuum US, 2007.

Herrin, Judith. Byzantium: The Surprising Life of a Medieval Empire. England: Penguin Books, 2008.

1. Marcus Rautman, Daily Life in the Byzantine Empire (Connecticut: Greenwood Press, 2006), 62; Jonathan Harris, Constantinople: Capital of Byzantium (New York: Continuum US, 2007), 43-44; Judith Herrin, Byzantium: The Surprising Life of a Medieval Empire (England: Penguin Books, 2008), 5.
2. Rautman, Daily Life in the Byzantine Empire, 62; Harris, Constantinople: Capital of Byzantium, 44-45; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 5.
3. Rautman, Daily Life in the Byzantine Empire, 70; Harris, Constantinople: Capital of Byzantium, 45; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 5.
4. Rautman, Daily Life in the Byzantine Empire, 70; Harris, Constantinople: Capital of Byzantium, 46-47; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 14.
5. Rautman, Daily Life in the Byzantine Empire, 70; Harris, Constantinople: Capital of Byzantium, 46-47; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 14.
6. Rautman, Daily Life in the Byzantine Empire, 70; Harris, Constantinople: Capital of Byzantium, 46-47; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 14.
7. Harris, Constantinople: Capital of Byzantium, 52.
8. Harris, Constantinople: Capital of Byzantium, 52-53.
9. Harris, Constantinople: Capital of Byzantium, 53.
10. Rautman, Daily Life in the Byzantine Empire, 72; Harris, Constantinople: Capital of Byzantium, 47; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 14.
11. Rautman, Daily Life in the Byzantine Empire, 221-223; Harris, Constantinople: Capital of Byzantium, 48-49, 57; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 141-142, 147.
12. Rautman, Daily Life in the Byzantine Empire, 72-75; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 6, 14-15.
13. Rautman, Daily Life in the Byzantine Empire, 75-76; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 5.
14. Rautman, Daily Life in the Byzantine Empire, 76; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 14.
15. Harris, Constantinople: Capital of Byzantium, 40, 56-58; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 6.
16. Harris, Constantinople: Capital of Byzantium, 56-58; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 90.
17. Harris, Constantinople: Capital of Byzantium, 47-50; Herrin, Byzantium: The Surprising Life of a Medieval Empire, 15-16.

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