Between 626 and 1453, Constantinople—capital of the Byzantine Empire and heir to ancient Rome—faced twenty major sieges. Across these eight centuries, the city resisted waves of external threats and internal conflicts, until its final fall to the Ottomans marked the end of the Middle Ages and the last breath of the Roman Empire. Built in the 5th century, the Theodosian Walls stood as stone witnesses to the medieval world: its rise, divisions, violence, and ultimate transformation.
The Theodosian Walls: Fortress of Continuity
Constructed under Emperor Theodosius II in the early 400s, the triple-wall system of Constantinople stretched over 5 km west of the old city and was considered impregnable for centuries. These walls were not only architectural marvels; they also symbolised the continuity of Roman civilisation in the East. Where Rome had fallen to the Goths in 476, Constantinople stood firm, projecting imperial legitimacy and urban permanence long after the Western Empire’s collapse.
The Early Sieges: A City Under Siege from All Fronts
Siege of 626 depicted in the Manasses Chronicle
1. 626 – The first major siege of the city in the Middle Ages came during the reign of Emperor Heraclius. A coalition of Avars, Slavs, and Sassanid Persians attacked while Heraclius campaigned in the East. The successful defence, bolstered by divine favour and a naval victory on the Golden Horn, was seen as a miracle and reinforced the city’s mythic invincibility.
2. 674–678 – The first Arab siege, under the Umayyads, marked a new phase: Islamic expansion had reached the walls of Byzantium. Constantinople’s victory, thanks in part to the use of Greek fire, preserved Christian rule in Eastern Europe and slowed the Arab advance for decades.
3. 717–718 – A second and much more dangerous Arab siege under Caliph Umar II tested the empire’s endurance. Emperor Leo III held firm, aided by Bulgarian allies and harsh winter conditions. The failure of this siege was a turning point in the Islamic-Byzantine wars, stabilising the empire’s eastern frontier.
The North Presses Down: Slavs, Bulgars, and Rus’
4. 813 – The Bulgarian Khan Krum laid siege after several victories. The Byzantines, though shaken, held out. The episode showed that the Balkans were no longer imperial hinterlands but contested regions, foreshadowing centuries of northern pressure.
The 860 attack depicted in the Radzivill Chronicle.
5. 860 – The Rus’, Norse-descended rulers of Kievan Rus’, launched a surprise naval raid. Though short-lived, it signalled the emergence of a new power in the north and exposed Constantinople’s naval vulnerabilities.
6. 907 – A second Rus’ attack, semi-legendary, reportedly ended with a treaty, revealing a shift towards diplomacy and trade.
7. 941 – A third Rus’ assault, more serious, was repelled with Greek fire, underscoring the city’s technological advantage.
8. 959 – The Hungarians, under a leader named Apor, unsuccessfully attempted to penetrate the city’s defences. Their failure demonstrated both the city’s resilience and the growing irrelevance of nomadic cavalry-based warfare in sieges.
Civil Wars and Internal Division
Thomas and his army assail Constantinople. Miniature from the Madrid Skylitzes.
9. 821–823 – The general Thomas the Slav, claiming the imperial title, laid siege during a civil war. Despite wide support, he failed to breach the walls. This siege revealed deep fragmentation within the empire and the dangers of internal division during external threats.
10. 1047 – Leon Tornikios, a cousin of the emperor, led another revolt and attempted a siege. His failure reflected the declining discipline and loyalty in the military aristocracy and foreshadowed the empire’s weakening under the pressures of feudalism.
The Fourth Crusade and the Great Schism
Attack of the Crusaders on Constantinople, miniature in a manuscript of 9 La Conquête de Constantinople by Geoffreoy de Villehardouin, Venetian ms.
11. 1203 – Crusaders, diverted from their original goal, besieged Constantinople to reinstall the deposed Emperor Isaac II Angelos. Though the city surrendered, this foreign intervention deeply undermined imperial legitimacy.
12. 1204 – A second siege by the same Crusaders resulted in the sack of Constantinople. Churches were looted; a fire devastated the city. The consequences of this siege inckude the Latin Empire replacing the Byzantine state for 57 years, and the final split between Catholic West and Orthodox East—no reconciliation was possible after this act of Christian-on-Christian violence. Byzantium never fully recovered its wealth or power.
Fragmentation, Recovery, and Decline
13. 1235 – A failed siege by Bulgarian and Nicene forces trying to retake the city from Latin rulers.
14. 1260 – A second failed Nicene attempt, reflecting the growing determination to restore Byzantium.
15. 1261 – The general Alexios Strategopoulos retook Constantinople for the Byzantines in a largely bloodless recapture. Though symbolically important, the city was poor, underpopulated, and its empire reduced to fragments.
The Ottoman Shadow
16. 1391–1392 – The first Ottoman siege, during the rise of Bayezid I, showed the strategic vulnerability of the city surrounded by Turkish principalities.
17. 1394–1402 – A longer, more dangerous siege followed. Constantinople was only spared due to the intervention of Tamerlane, who defeated Bayezid.
18. 1411 – During the Ottoman civil war (Interregnum), the city was again threatened, highlighting Byzantine dependence on Ottoman factionalism.
19. 1422 – Sultan Murad II launched another failed siege. The city remained intact, but by now it was economically and militarily exhausted.
The End: 1453
Le siège de Constantinople (1453) by Jean Le Tavernier after 1455
20. 1453 – Mehmet II, aged only 21, launched a full-scale siege with advanced artillery. After 53 days, Constantinople fell on 29 May.
The last emperor, Constantine XI Palaiologos, died in battle.
The city became Istanbul—capital of the Ottoman Empire.
This event marked the final end of the Roman Empire—more than 1,100 years after the fall of Rome. It also marked the end of the Middle Ages, ushering in the Renaissance and Early Modern period.
The twenty medieval sieges of Constantinople are not isolated episodes. They reflect the entire trajectory of medieval Europe: the struggle between Christianity and Islam, the fracture of Christendom, the rise of Slavic and Turkic powers, the decline of imperial authority, and the shift from medieval to early modern geopolitics.
Through it all, the Theodosian Walls stood—until gunpowder breached them. Their long defence of the Roman ideal was heroic, but not eternal. With the fall of Constantinople, the Middle Ages closed.
Dr Lorris Chevalier, who has a Ph.D. in medieval literature, is a historical advisor for movies, including The Last Duel and Napoleon. Click here to view his website.
Top Image: The Siege of Constantinople (626) by the Avars on a mural at the Moldoviţa Monastery, Romania. The siege depicted in actual fact is the Fall of Constantinople to the Ottomans in 1453, as illustrated by the presence of artillery and the dress of the besieging forces.
By Lorris Chevalier
Between 626 and 1453, Constantinople—capital of the Byzantine Empire and heir to ancient Rome—faced twenty major sieges. Across these eight centuries, the city resisted waves of external threats and internal conflicts, until its final fall to the Ottomans marked the end of the Middle Ages and the last breath of the Roman Empire. Built in the 5th century, the Theodosian Walls stood as stone witnesses to the medieval world: its rise, divisions, violence, and ultimate transformation.
The Theodosian Walls: Fortress of Continuity
Constructed under Emperor Theodosius II in the early 400s, the triple-wall system of Constantinople stretched over 5 km west of the old city and was considered impregnable for centuries. These walls were not only architectural marvels; they also symbolised the continuity of Roman civilisation in the East. Where Rome had fallen to the Goths in 476, Constantinople stood firm, projecting imperial legitimacy and urban permanence long after the Western Empire’s collapse.
The Early Sieges: A City Under Siege from All Fronts
1. 626 – The first major siege of the city in the Middle Ages came during the reign of Emperor Heraclius. A coalition of Avars, Slavs, and Sassanid Persians attacked while Heraclius campaigned in the East. The successful defence, bolstered by divine favour and a naval victory on the Golden Horn, was seen as a miracle and reinforced the city’s mythic invincibility.
2. 674–678 – The first Arab siege, under the Umayyads, marked a new phase: Islamic expansion had reached the walls of Byzantium. Constantinople’s victory, thanks in part to the use of Greek fire, preserved Christian rule in Eastern Europe and slowed the Arab advance for decades.
3. 717–718 – A second and much more dangerous Arab siege under Caliph Umar II tested the empire’s endurance. Emperor Leo III held firm, aided by Bulgarian allies and harsh winter conditions. The failure of this siege was a turning point in the Islamic-Byzantine wars, stabilising the empire’s eastern frontier.
The North Presses Down: Slavs, Bulgars, and Rus’
4. 813 – The Bulgarian Khan Krum laid siege after several victories. The Byzantines, though shaken, held out. The episode showed that the Balkans were no longer imperial hinterlands but contested regions, foreshadowing centuries of northern pressure.
5. 860 – The Rus’, Norse-descended rulers of Kievan Rus’, launched a surprise naval raid. Though short-lived, it signalled the emergence of a new power in the north and exposed Constantinople’s naval vulnerabilities.
6. 907 – A second Rus’ attack, semi-legendary, reportedly ended with a treaty, revealing a shift towards diplomacy and trade.
7. 941 – A third Rus’ assault, more serious, was repelled with Greek fire, underscoring the city’s technological advantage.
8. 959 – The Hungarians, under a leader named Apor, unsuccessfully attempted to penetrate the city’s defences. Their failure demonstrated both the city’s resilience and the growing irrelevance of nomadic cavalry-based warfare in sieges.
Civil Wars and Internal Division
9. 821–823 – The general Thomas the Slav, claiming the imperial title, laid siege during a civil war. Despite wide support, he failed to breach the walls. This siege revealed deep fragmentation within the empire and the dangers of internal division during external threats.
10. 1047 – Leon Tornikios, a cousin of the emperor, led another revolt and attempted a siege. His failure reflected the declining discipline and loyalty in the military aristocracy and foreshadowed the empire’s weakening under the pressures of feudalism.
The Fourth Crusade and the Great Schism
11. 1203 – Crusaders, diverted from their original goal, besieged Constantinople to reinstall the deposed Emperor Isaac II Angelos. Though the city surrendered, this foreign intervention deeply undermined imperial legitimacy.
12. 1204 – A second siege by the same Crusaders resulted in the sack of Constantinople. Churches were looted; a fire devastated the city. The consequences of this siege inckude the Latin Empire replacing the Byzantine state for 57 years, and the final split between Catholic West and Orthodox East—no reconciliation was possible after this act of Christian-on-Christian violence. Byzantium never fully recovered its wealth or power.
Fragmentation, Recovery, and Decline
13. 1235 – A failed siege by Bulgarian and Nicene forces trying to retake the city from Latin rulers.
14. 1260 – A second failed Nicene attempt, reflecting the growing determination to restore Byzantium.
15. 1261 – The general Alexios Strategopoulos retook Constantinople for the Byzantines in a largely bloodless recapture. Though symbolically important, the city was poor, underpopulated, and its empire reduced to fragments.
The Ottoman Shadow
16. 1391–1392 – The first Ottoman siege, during the rise of Bayezid I, showed the strategic vulnerability of the city surrounded by Turkish principalities.
17. 1394–1402 – A longer, more dangerous siege followed. Constantinople was only spared due to the intervention of Tamerlane, who defeated Bayezid.
18. 1411 – During the Ottoman civil war (Interregnum), the city was again threatened, highlighting Byzantine dependence on Ottoman factionalism.
19. 1422 – Sultan Murad II launched another failed siege. The city remained intact, but by now it was economically and militarily exhausted.
The End: 1453
20. 1453 – Mehmet II, aged only 21, launched a full-scale siege with advanced artillery. After 53 days, Constantinople fell on 29 May.
The last emperor, Constantine XI Palaiologos, died in battle.
The city became Istanbul—capital of the Ottoman Empire.
This event marked the final end of the Roman Empire—more than 1,100 years after the fall of Rome. It also marked the end of the Middle Ages, ushering in the Renaissance and Early Modern period.
The twenty medieval sieges of Constantinople are not isolated episodes. They reflect the entire trajectory of medieval Europe: the struggle between Christianity and Islam, the fracture of Christendom, the rise of Slavic and Turkic powers, the decline of imperial authority, and the shift from medieval to early modern geopolitics.
Through it all, the Theodosian Walls stood—until gunpowder breached them. Their long defence of the Roman ideal was heroic, but not eternal. With the fall of Constantinople, the Middle Ages closed.
Dr Lorris Chevalier, who has a Ph.D. in medieval literature, is a historical advisor for movies, including The Last Duel and Napoleon. Click here to view his website.
Click here to read more from Lorris Chevalier
Top Image: The Siege of Constantinople (626) by the Avars on a mural at the Moldoviţa Monastery, Romania. The siege depicted in actual fact is the Fall of Constantinople to the Ottomans in 1453, as illustrated by the presence of artillery and the dress of the besieging forces.
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