Forces of the Umayyad Caliphate abandoned a year-long siege of Constantinople, ending their goal of conquering the Byzantine Empire. Umayyad Caliphate: The Umayyad Caliphate, or the Umayyad Empire, was the second Islamic caliphate, ruled by the Umayyad dynasty from 661 to 750. It succeeded the Rashidun Caliphate, whose third caliph, Uthman ibn Affan, was also a member of the Umayyad clan. The Umayyad family established hereditary rule under Mu'awiya ibn Abi Sufyan, the long-time governor of Syria, who became caliph in 661 after emerging victorious in the First Fitna. Syria served as the caliphate's metropolitan province thereafter, with Damascus as its capital. August 15, 718. Wiki link