The Frankish emperor Louis II campaigned against the Emirate of Bari continuously from 866 until 871. Louis was allied with the Lombards of southern Italy from the start, but an attempt at joint action with the Byzantine Empire failed in 869. In the final siege of the city of Bari in 871, Louis was assisted by a Slavic fleet from across the Adriatic. The city fell and the emir was taken captive, bringing the emirate to an end, but a Saracen presence remained at Taranto. Louis himself was betrayed by his Lombard allies six months after his victory and had to leave southern Italy.