From 534 AD to 642 AD, the city returned to eastern Romans under the Byzantine Empire, after a defeat of the vandals in 534, and they build the Fort of Bizerte (now the Fort of Kasba).
Bizerte was taken by Arabs in 647 in their first invasion, but reverted to Byzantine control until they were defeated and driven from North Africa finally in 695-98, by the troops of Charles V of the Holy Roman Empire in 1535 and then by the Turks in 1574.