Apart from the campaigns in Saxony, in Italy, and in Bavaria, necessary to the integrity of the Frankish empire, there were various frontier wars undertaken, not for the purpose of incorporating fresh territory, but rather to impress upon contiguous peoples the power and prestige of Frankish arms. The occupation of Bavaria brought Charles in contact with the Avars, and his control of Aquitaine gave him as near neighbors the Moslems of Spain, those enemies with whom his grandfather, Charles Martel, had tried conclusions on the historic field of Poictiers. This defeat had been inflicted on the conquerors of Spain at a time when the Ommayad Caliphate ruled over a united Moslem world. But the great internal revolution had broken this unity in 750, eighteen years before the accession of Charles. The last Ommayad Caliph, Merwan, after the great battle of Mosul, had been obliged to flee from Damascus to Egypt and had there met his death. Shortly afterward eighty members of his house were massacred by treachery at a banquet. Only one of the family escaped, Abderahman, the son of Merwan, who, after many adventures, reached Morocco, and was there invited to assume the rule of Moslem Spain, where the jealousies of the Emirs, the lieutenants of the far-distant Caliph in the East, had produced an era of misgovernment and faction. So began in 755 the Caliphate of Cordova, and with it the most brilliant period of Mohammedan rule in Spain. But Abderahman was not accepted as supreme head of the Spanish Moslems without active protest; the Eastern Caliphate of the Abbasides had many supporters in the peninsula, and it was to Charles that they appealed for aid in resisting the Ommayad house. Naturally, the internal disputes of the Spanish Moslems constituted by themselves no ground for Frankish intervention. But the appeal was reinforced by promises that various Spanish cities would open their gates if Charles would undertake to cross the Pyrenees with an adequate army. This offer was made to Charles by Moslem envoys, who appeared before him at Paderborn, where he was holding a formal assembly (placitum) of the Frankish host during the early course of the Saxon war. The prospects of valuable territorial acquisition prompted the ruler of the Franks to embark on this hazardous expedition. There is no proof whatsoever it was undertaken to aid, as a kind of crusade, the feeble kingdom of the Asturias, where the heirs of the Visigoths were still maintaining the Christian cause against the Moslems.