As early as 668 the Caliph Muawiyah I received an invitation from Saborios, the commander of the troops in Armenia, to help overthrow the Emperor at Constantinople. He sent an army under his son Yazid against the Byzantine Empire. Yazid reached Chalcedon and took the important Byzantine center Amorion. While the city was quickly recovered, the Arabs next attacked Carthage and Sicily in 669. In 670 the Arabs captured Cyzicus and set up a base from which to launch further attacks into the heart of the Empire. Their fleet captured Smyrna and other coastal cities in 672.