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[Creeperopolis]

The first Arab siege of Constantinople in 674–678 was a major conflict of the Arab–Byzantine wars, and the first culmination of the Umayyad Caliphate's expansionist strategy towards the Byzantine Empire, led by Caliph Mu'awiya I. Mu'awiya, who had emerged in 661 as the ruler of the Muslim Arab empire following a civil war, renewed aggressive warfare against Byzantium after a lapse of some years and hoped to deliver a lethal blow by capturing the Byzantine capital of Constantinople.

As reported by the Byzantine chronicler Theophanes the Confessor, the Arab attack was methodical: in 672–673 Arab fleets secured bases along the coasts of Asia Minor and then installed a loose blockade around Constantinople. They used the peninsula of Cyzicus near the city as a base to spend the winter and returned every spring to launch attacks against the city's fortifications. Finally the Byzantines, under Emperor Constantine IV, destroyed the Arab navy using a new invention, the liquid incendiary substance known as Greek fire. The Byzantines also defeated the Arab land army in Asia Minor, forcing them to lift the siege. The Byzantine victory was of major importance for the survival of the Byzantine state, as the Arab threat receded for a time. A peace treaty was signed soon after, and following the outbreak of another Muslim civil war, the Byzantines even experienced a brief period of ascendancy over the Caliphate. The siege was the first major Arab defeat in 50 years of expansion and temporarily stabilized the Byzantine Empire after decades of war and defeats.

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 in 669, led by Mu'awiya's son, the future ruler Yazid. As a result, the veracity of Theophanes's account was questioned in 2010 by Oxford scholar James Howard-Johnston, and more recently by Marek Jankowiak. Their analyses have placed more emphasis on the Arabic and Syriac sources, but have drawn different conclusions about the dating and existence of the siege.

News of a large-scale siege of Constantinople and a subsequent peace treaty reached China, where they were recorded in later histories of the Tang dynasty.