Nicephorus, went so far in allying himself with Charles, that he consented to recognise him as Emperor of the West, a concession accepted with pride by the Franks, and regarded as a lamentable token of weakness by the Constantinopolitans (812). One of the consequences of the conquests of Charles in Italy was to bring the Franks into collision with the Saracen pirates, who infested the central Mediterranean, making their harbourage in the ports of the islands which face the western coast of the peninsula. [Sidenote: Wars with Saracen pirates.] At a date which cannot be accurately fixed, the Franks took possession of Corsica and Sardinia, hunting out the Saracen colonists who had conquered the islands from the East-Romans some fifty or sixty years before. In 799 the Franks also took possession of the Balearic islands. These distant dependencies were attacked and ravaged by fleets from Spain on more than one occasion, but they were held down to the close of the reign of Charles. They were given in charge to the counts of Genoa and Tuscany, who seem to have been able to raise a considerable fleet, and more than once gained naval victories over the plundering Moor. But the most serious struggle between Charles and the Moslems took place in Spain, where during the whole of the second period of his reign the fighting was almost continuous. The permanent advance of the Christians beyond the Pyrenees began with the capture of Gerona in 785. The conduct of the war fell mainly into the hands of Lewis, the third son of Charles, whom his father had named king of Aquitaine, and trusted with all the affairs of the south-west. He and his chief captain and councillor William, count of Toulouse—a great hero in the Frankish romances—had to deal with the two first Ommeyad kings of Cordova, Abderahman (755-88) and Hisham (788-897), both strong and capable rulers, from whom it was by no means easy to win territory. [Sidenote: Conquests in Spain.] Nevertheless the Christian border slowly advanced, owing to the seditious and turbulent Moslem governors, who were always rebelling against their masters, and calling in Frankish aid. In 795 the newly-won land beyond the Pyrenees—around the towns of Gerona, Cardona, Urgel, and Ausona—was made into a separate government, the March of Spain, and intrusted to a Margrave of its own, instead of forming a dependency of the duchy of Septimania. Barcelona, the greatest town of Catalonia, was added to the March in 797, by the treachery of its governor Zeid, who, failing in a rebellion against his master at Cordova, handed the place over to the Franks. The Moors recovered it for a moment in 799, but king Lewis then came over the Pyrenees with the whole levy of Aquitaine, and laid siege to the town. It held out for nearly two years, but fell in 801, conquered by famine, after the Franks had walled it in with a circumvallation, and sat before it in their huts for the whole winter of 800-801. The Moorish population departed _en