The Fall of Constantinople in 1453: How Mehmed II Ended the Byzantine Empire

A weakened empire behind ancient walls

By the mid-15th century the Byzantine Empire had shrunk, after centuries of war with Ottoman, Serbian and Bulgarian forces, to little more than the city of Constantinople itself and a few scattered territories, according to Wikipedia's summary of the siege. A long-standing religious split between the Orthodox East and the Catholic West also made it hard for Emperor Constantine XI to secure sustained military help from Europe.

The city was still ringed by the Theodosian Walls, a triple-fortification system built in the 5th century under Emperor Theodosius II, according to World History Encyclopedia. It combined an outer wall with a patrol track, a middle wall with towers, and a massive inner wall nearly 5 metres thick and 12 metres high, studded with 96 towers roughly every 70 metres along a line about 6.5 kilometres across the peninsula.

The problem was manpower, not masonry. The Byzantine historian Georges Sphrantzes, who witnessed the siege, reported that the emperor's own troops numbered fewer than 5,000 men — far too few, World History Encyclopedia notes, to cover the roughly 19 kilometres of walls that ran around the entire city. Adding about 2,000 Genoese and Venetian volunteers brought the total defending force to around 7,000, Wikipedia's account states.

Mehmed's siege machine: cannons and ships hauled overland

Mehmed II was born on 30 March 1432 and was 21 years old when he ordered the siege, having held the Ottoman throne since 1451 after a brief earlier reign as a child in 1444–1446, World History Encyclopedia's biography of the sultan states. His success at Constantinople later earned him the byname "Fatih," or the Conqueror.

Modern historians estimate Mehmed's army at 50,000 to 80,000 soldiers, including 5,000 to 10,000 elite Janissaries, backed by roughly 70 cannons and a fleet of around 110 ships, according to Wikipedia; the figure once given in older accounts, up to 200,000, is now considered unreliable by scholars cited by World History Encyclopedia.

The decisive weapon was artillery built by a Hungarian founder, named Orban in some sources and Urban in others. According to HistoryNet, Orban's largest bombard measured about 27 feet long with a 30-inch barrel reinforced by 8 inches of solid bronze, and fired stone balls weighing over half a ton. It took roughly six weeks to haul the gun from the Ottoman capital at Edirne to Constantinople in early April 1453. Overall bombardment began on 12 April, and by 28 May, after 47 days, the Ottomans had fired an estimated 5,000 shots using about 55,000 pounds of gunpowder, HistoryNet reports.

The Byzantines and their Genoese allies in Galata had stretched a heavy chain across the mouth of the Golden Horn to keep Ottoman ships out of the inner harbour. On the night of 22 April, Mehmed had about 70 ships hauled overland on a road of greased logs over the hill behind Galata and relaunched directly into the Golden Horn, bypassing the chain entirely, according to both Wikipedia and World History Encyclopedia. The manoeuvre forced the already thin Byzantine garrison to stretch further to cover additional sea walls.

Fifty-three days, then the final assault

• 2 April 1453 — Mehmed's army arrives outside Constantinople
• 6 April — the siege formally begins
• 12 April — full cannon bombardment of the land walls starts
• 22 April — Ottoman ships are dragged overland into the Golden Horn
• 29 May — final assault; the city falls

The siege lasted 53 days from its formal start to the city's fall, Wikipedia's account states. Shortly after midnight on 29 May, Mehmed launched a final, overwhelming assault in three successive waves — first auxiliary troops, then irregular azaps, and finally the elite Janissary corps, according to Wikipedia and to World History Encyclopedia's biography of Mehmed. The defence began to collapse when the Genoese commander Giovanni Giustiniani, who had led the land defences alongside the emperor, was wounded and evacuated, spreading panic among the remaining defenders, Wikipedia reports.

Constantine XI died in the fighting, most likely near the Gate of St. Romanos, after reportedly tearing off his imperial insignia so his body could not be identified and desecrated, World History Encyclopedia states. No confirmed body was ever recovered, which later gave rise to a legend that the emperor had been magically preserved rather than killed.

Aftermath: a new capital and the end of an era

World History Encyclopedia puts the immediate death toll at about 4,000, a figure Wikipedia's summary also cites, adding that more than 550 Venetian civilians died as well. Estimates of how many residents were enslaved differ between sources: World History Encyclopedia reports more than 50,000 people taken into slavery, while Wikipedia's summary gives a figure of around 30,000.

Mehmed entered the city and ordered the Hagia Sophia, the main cathedral of Eastern Christianity for roughly 1,200 years, converted into a mosque almost immediately, according to World History Encyclopedia, which also states that he had prominent surviving Byzantine nobles executed in the aftermath.

World History Encyclopedia notes that Constantinople had served as the capital of the Eastern Roman Empire, or Byzantine Empire, for well over 1,000 years, while Wikipedia's account describes the fall as marking the effective end of the Roman Empire, which it traces back to around 27 BCE, after nearly 1,500 years. Wikipedia also calls the event a watershed of the Late Middle Ages, and adds that the siege demonstrated gunpowder artillery could overcome even renowned medieval fortifications such as the Theodosian Walls, a lesson that reshaped siege warfare across Europe in the following decades.