Sieges of constantinople

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 (r. 610–641) 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.

The Second Arab siege of Constantinople in 717–718 was a combined land and sea offensive by the Muslim Arabs of the Umayyad Caliphate against the capital city of the Byzantine Empire, Constantinople.

The city was defended by, at most, 10,000 men. The Turks had between 100,000 and 150,000 men on their side.Decisive Ottoman victory, Fall of the Byzantine Empire, Constantinople becomes the Ottoman Empire's new capital

The siege left several traces in the legends of the nascent Muslim world, although it is conflated with accounts of another expedition against the city a few years previously, led by the future Caliph Yazid I. As a result, the veracity of Theophanes's account was questioned in 2010 by Oxford scholar James Howard-Johnston, who placed more emphasis on the Arabic and Syriac sources. On the other hand, echoes of a large siege of Constantinople and a subsequent peace treaty reached China, where they were recorded in later histories of the Tang dynasty.