Siege of Constantinople Ends: Byzantine Capital Falls to Ottoman Turks

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Siege of Constantinople Ends: Byzantine Capital Falls to Ottoman Turks

"Siege of Constantinople" by Philippe de Mazarolle c. 1453-1475
From the Chronique de Charles VII by Jean Chartier
Currently located at the National Library of France, Paris
(Unless otherwise indicated, all illustrations are courtesy of Wikipedia)

Today in Military History: May 29, 1453

Today's signature event is considered by many scholars and historians as the end of the Middle Ages. It is also regarded as the final, defining end of the Roman Empire.


Since its founding in 330 by Roman Emperor Constantine the Great, Constantinople was considered the "second Rome." After the decline and fall of the Western Roman Empire in the late fifth century, the Eastern Empire acquired the political, social, and religious mantle of its predecessor. In the early sixth century, the Byzantine Empire controlled large portions of land that were once part-and-parcel of the original Roman Empire. However, several wars with the Sassanid Persian Empire, the migrations of various barbarian tribes, and the rise of the followers of Islam all contributed to the East Roman Empire's contraction.

However, the capture of the city by western European forces in 1204 signaled the beginning of the end of the "Great City." [Readers interested in that episode are asked to read my Burn Pit posts from April of 2013, Byzantine Capital of Constantinople Captured by Crusaders, Sacked for Three Days and Part II – Siege and Fall of Constantinople.] By the mid-fifteenth century, the Byzantine Empire had shrunk to an area that encompassed the area immediately around the capital city, the southernmost portion of the Greek peninsula, and a few islands in the Aegean Sea (see the map below). The only real allies – military and economic – the Romans had were the Italian maritime cities of Genoa and Venice.

Map of eastern Mediterranean c. 1450 (Byzantine possessions in purple)
Map of eastern Mediterranean c. 1450 (Byzantine possessions in purple)

In the late fourteenth century, the rise of the Ottoman Turks presented the single greatest threat to the continuation of the Byzantine kingdom. The accession of Mehmed II as Turkish sultan in 1451 was initially not believed to threaten Constantinople. Only 19 years of age, he assured Byzantine ambassadors that he did not present a real threat to them. However, he was determined to final bring down the "Great City" once and for all. To that end, Mehmed began preparations to accomplish this goal.

In April of 1452, Mehmed ordered the construction of a fortified castle across the Bosphorus northeast of the Byzantine capital. With up to 1000 mason working constantly, the new stronghold was constructed in a little over four-and-a-half months, under the personal supervision of the new sultan. This Turkish fortification was called Rumelihisari, and was a companion to Anadoluhisari, a strongpoint established on the Asian side of the strait by Mehmed's grandfather. The two castles consequently controlled the sea lanes to Constantinople, effectively blocking any avenues for relief by sea to the city.

[The newer Ottoman fort was originally named Boğzkesen, which can be translated as either "strait-blocker" or "throat-cutter," to indicate its important strategic position.]

Rumelihisari was garrisoned by 400 Janissaries (the sultan's elite bodyguards) and a number of large cannon were place in one of its three main towers. Shortly after the fortress was fully garrisoned, a Venetian merchant ship entered the Bosphorus from the Black Sea. When signaled to stop for inspection, the vessel ignored the command. Artillery from Rumelihisari bombarded and sank the ship, and 20 surviving crewmen were beheaded on the beach. This incident was a stark demonstration that the Byzantine capital was in grave peril.

Rumelihisari today, outside Istanbul, Turkey
Rumelihisari today, outside Istanbul, Turkey

Constantinople and Its Defenses

The city known variously as the "New Rome," the "Great City," Konstantiniyye, Tsarigrad, and Miklagard had once held a population estimated at between 500,000 and 800,000 inhabitants in the 9th and 10th centuries. The capture of the city in 1204 by Crusaders and the Black Death of 1347 greatly depopulated the city. By 1450 there were only about 50,000 people in the city, including thousands of refugees from neighboring areas that had been forced out of their homes by the Turks. In fact, one source describes Constantinople as a series of villages within the city's walls.

In its 1100+ year existence, Constantinople had withstood a number of sieges. In nearly every case the stout walls, brave defenders, and intrepid Byzantine navy had broken armies of Arabs, Avars, Bulgars, Persians, and Rus'. The Ottoman Turks had attempted three sieges previously, in 1390-1402, 1411, and 1422. The city was literally a walled fortress; in addition to the Theodosian walls guarding the western side of Constantinople, every single foot of the city's shoreline was lined with strong fortifications. These extensive walls totaled some 20 kilometers.

Computer recreation of the Theodosian Walls, showing moat in foreground [Photograph courtesy of]
Computer recreation of the Theodosian Walls, showing moat in foreground
[Photograph courtesy of]

With the loss of its traditional recruiting grounds in the Balkans, Greece, and Asia Minor, the Byzantines began to rely more heavily upon hiring mercenary units. The garrison of Miklagard totaled about 7000 soldiers, of which 2000 were foreigners. [One sellsword unit of note inside the city was a Turkish contingent, hired directly by the Emperor Constantine XI, kept their oath of allegiance, dying to a man in the siege's final days.] The small size of the garrison forced the Byzantines initially to defend only the Theodosian Walls. There were a few reserve forces in other locations of the city. The defenders also had a number of cannon to defend the city.

Another vital link in the defenses of the Great City was the floating chain which extended from the city itself across the Golden Horn to the suburb of Galata (which had grown up around a stronghold built specifically to guard the chain). This chain, which floated on wooden logs, was strong enough to prevent any Turkish ship from entering the harbor. Using a series of winches, the chain could be loosened to allow ships to enter the Golden Horn.

Remains of Golden Horn chain today, on display in the Istanbul Military Museum, Turkey [Photograph courtesy of]
Remains of Golden Horn chain today, on display in the Istanbul Military Museum, Turkey
[Photograph courtesy of]

The Byzantine navy, though well-trained and well-equipped, was composed of 26 ships – 10 Byzantine and the remainder from Genoa, Pisa, and other Western nations. In addition, a force of Genoese and Pisan sailors was assigned the defense of the Italian quarter, an area of the city inhabited mainly by Italian merchants and sailors across the Golden Horn from Galata.

Ottoman Turk Forces

Mehmed II was determined to capture Konstantiniyye at almost any cost. He gathered men from his entire domain, his army eventually totaling between 50,000 and 80,000 Ottoman soldiers. This number included between 5000 and 10,000 Janissaries, the sultan's bodyguards who were former Christian slaves converted to Islam and highly trained as elite warriors. The army also included thousands of Christian troops from nearby conquered regions, including some 1500 Serbians under their despot Đurađ Branković. Almost certainly there were subject troops from Hungary, Bulgaria, and Wallachia (modern-day Romania) in the Turkish force as well.

One of the advantages which the Turks enjoyed was a number of cannon that would be used to batter the walls of Constantinople. One the sultan's most valuable assets was a Hungarian (or possibly German) engineer named Orban. He had offered his services to the Byzantines, but they did not have sufficient funds to employ him. Once in Mehmed's employ, he began construction of a bronze cannon the likes of which the world had never seen before.

This colossal artillery piece – christened "Basilica" – was over 27 feet long, 30 inches in diameter, and had walls 8 inches thick to absorb the extreme force of the huge gunpowder loads. It fired stone balls weighing between 600 and 1500 pounds up to a mile. It became the centerpiece of the sultan's strategy to batter down the walls of Constantinople. It required sixty oxen and 400 men to transport the gun from its foundry Adrianople the 140 miles to Constantinople, and took six weeks to reach Constantinople.

In addition to this giant marvel, Orban and his men cast at least 69 smaller cannon to "batter the very walls of Babylon" (according to Orban himself). There were also some cannon with a barrel length of up to 14 feet, not quite as imposing as the "Basilica," but still formidable. A number of other large siege weapons – including trebuchets – were also constructed and transported to the Byzantine capital.

Artist's conception of Turkish super-cannon 'Basilica' during siege of Constantinople [Image courtesy of]
Artist's conception of Turkish super-cannon "Basilica" during siege of Constantinople
[Image courtesy of]

The Ottoman naval force was equally formidable, consisting of about 126 ships, including a number of large and small fighting galleys, rowing boats and 20 horse transports.

Tomorrow: Part II, Siege of Constantinople.

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