The wars with Turkey had a special significance because of the ever impending peril from Moslem northern Africa. The pirates of the Berber, or Barbary, Coast, as the lands in northwestern Africa are often called, seemed to be more than ever audacious in the early years of the reign of Charles. Not only did they attack Spanish ships and even Spanish ports, but they also made numerous incursions inland in the peninsula. Aside from the loss in captives and in economic wealth that these visitations represented, they served to remind the authorities of the Moslem sympathies of Spanish Moriscos and of the ease with which a Moslem invasion might be effected. Furthermore the conquests of Isabella and Ximénez had created Castilian interests in northern Africa, of both a political and an economic character, which were in need of defence against the efforts of the tributary princes to free themselves by Turkish aid. The situation was aggravated by the achievements of a renegade Greek adventurer and pirate, known best by the sobriquet “Barbarossa.” This daring corsair became so powerful that he was able to dethrone the king of Algiers and set up his own brother in his stead. On the death of the latter at the hands of the Spaniards in 1518, Barbarossa placed the kingdom of Algiers under the protection of the sultan of Turkey, became himself an admiral in the Turkish navy, and soon afterward conquered the kingdom of Tunis, whence during many years he menaced the Spanish dominions in Italy. Charles in person led an expedition in 1535 which was successful in dethroning Barbarossa and in restoring the former king to the throne, but an expedition of 1541, sent against Algiers, was a dismal failure. On yet another frontier, that of Hungary, Spanish troops were called upon to meet the Turks, and there they contributed to the checking of that people at a time when their military power threatened Europe. The problem of northern Africa, however, had been little affected by the efforts of Charles. [Sidenote: Charles’ failure to stamp out Protestantism.]