Byzantine Defense Repels 626 AD Avar, Slavic and Persian Siege of Constantinople

On 7 August 626, a ten‑day siege of Constantinople was launched by a coalition of Avars, Slavic tribes and Persian forces. The attackers attempted to breach the city from both the Asian and European sides of the Bosphorus, but Byzantine defenses, coordinated by the city’s patriarch Sergius I, held firm.

Contemporary Byzantine sources attribute the failure of the siege to the intercession of the Theotokos (Virgin Mary), whose protection was celebrated in a church sermon recorded shortly after the first anniversary of the attack. The siege marked the first major medieval attempt to capture the imperial capital and demonstrated the resilience of the Eastern Roman Empire against a coordinated foreign assault.