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BATTLE // June 1, 0626

Siege of Constantinople

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Overview

The siege of Constantinople in 626 by the Sassanid Persians and Avars, aided by large numbers of allied Slavs, ended in a strategic victory for the Byzantines. The failure of the siege saved the empire from collapse, and, combined with other victories achieved by Emperor Heraclius the previous year and in 627, enabled Byzantium to regain its territories and end the destructive Roman–Persian Wars by enforcing a treaty with borders status quo c. 590.

Overview adapted from Wikipedia, licensed under CC BY-SA 4.0.

Significance

The Siege of Constantinople in 626 was a defining episode of the Byzantine–Sassanid War of 602–628, in which an 80,000-strong Sassanid force moved against a city defended by approximately 8,000 Byzantine troops. Constantinople's position at the junction of Europe and Asia, linking the Sea of Marmara to the Black Sea and situated along the Silk Road, made it the supreme strategic prize of the conflict. Its capture would have severed Byzantine control over a transcontinental hub through which commerce and military movement flowed between the two continents. The city's defense fell to a Byzantine command that included Patriarch Sergius, the general Bonus, and Theodore, operating at severe numerical disadvantage against Sassanid commanders including Shahrbaraz and Kardarigan under the direction of the khagan. The outcome of the siege is not recorded in the supplied sources, but the engagement itself represented the point at which the long war between Byzantium and the Sassanid Empire reached the imperial capital, making it a central moment in the broader contest over dominance of the Near East and the eastern Mediterranean world.

Forces & casualties

Troop strength

  • Sassanid Empire80,000
    medium
  • Byzantine Empire8,000
    medium

Sassanid Empire fielded a 10.0 : 1 numerical advantage

Commanders (7)

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Last verified July 2026
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