3 – The Umayyad Caliphate I (674 – 678)
This was the first of two major sieges by the Umayyad Caliphate and lasted a total of four years. In 661, Caliph Mu’awiya I emerged as the leader of the Muslim Arab Empire after winning a civil war. The catastrophic defeat at Yarmouk in 636 had forced the Byzantines to withdraw most of their remaining army to Asia Minor. By leaving the Levant, they opened up a path for the Rashidun Caliphate to conquer Syria and Egypt. Further inroads were made until the First Muslim Civil War which resulted in a temporary halt in attacks.
However, Mu’awiya resumed the attacks on the Byzantines and ravaged Asia Minor annually from 663 onwards. Each year, they returned to their Syrian bases. After several years, Mu’awiya knew it was necessary to capture Constantinople if the Arabs wished to secure Asia Minor. Over the next few years, the Arabs implemented a methodical approach and took important locations such as Kyzikos and Smyrna in 670. By 672/73, the Arabs fleets took several bases around the Asia Minor coast and began a loose blockade on the city of Constantinople.
The Arabs launched attacks on the city’s fortifications every spring for four years and retreated to Cyzicus in winter. Although the Arabs were not having an enormous amount of success, Emperor Constantine IV knew he needed to lift the siege to save other parts of the Empire. At that time, the Lombards attacked territory in Italy while the Slavs attacked Thessalonica. Constantine took a risk and decided to fight the Arabs in a head-on battle in 678.
Eventually, Byzantine ships sailed out of the Golden Horn and attacked the enemy with a secret weapon known as Greek Fire. The exact make-up of the weapon is still not known today. It was shot via a siphon and ignited a flame that enemies were unable to extinguish. At the same time, a Byzantine land army defeated a Muslim army in Asia Minor. The enormous losses suffered by the Arabs forced them to retreat, but they would be back within 40 years.