Since the mid-7th century, the Mediterranean Sea had become a battleground between the Muslim navies and the Byzantine navy. Very soon after their conquest of the Levant and Egypt, the nascent Caliphate built its own fleet, and in the Battle of the Masts in 655 shattered Byzantine naval supremacy, beginning a centuries-long series of conflicts over the control of the Mediterranean waterways. This enabled the Umayyad Caliphate to launch a major seaborne attempt to capture Constantinople in 674–678, followed by another huge land and naval expedition in 717–718, that was equally unsuccessful.[2][3] At the same time, by the end of the 7th century the Arabs had taken over Byzantine North Africa (known in Arabic as Ifriqiya), and in c. 700, Tunis was founded and quickly became a major Muslim naval base.