Charlemagne and his Empire 375 Moors in Spain. Against these it was necessary to protect his realms, and the second part of Charlemagne's reign was devoted to what may be called his foreign policy. A single campaign in 789 seems to have sufficed to subdue the Slavs, who lay to the north and east of the Saxons, and to force the Bohemians to acknowledge the supremacy of the Frankish king and pa}^ tribute to him. The necessity of protecting the Frankish realms agamst any The new uprising of these non-German nations led to the establish- maSaves"^ ment, on the confines of the kingdom, of marches, that is, districts under the military control of counts of the march, or ??iargraves} Their business was to prevent any invasion of the interior of the kingdom. Much depended upon the efficiency of these men ; in many cases they founded powerful families and later helped to break up the empire by establishing themselves as practically independent rulers. At an assembly that Charlemagne held in 777, ambassadors Charlemagne appeared before him from certain dissatisfied Mohammedans ^" ^^^'" in Spain. They had fallen out with the emir of Cordova ^ and now offered to become, the faithful subjects of Charlemagne if he would come to their aid. In consequence of this embassy he undertook his first expedition to Spain in the following year. After some years of war the district north of the Ebro was con- quered by the Franks, and Charlemagne established there the Spanish march. In this way he began that gradual expulsion of the Mohammedans from the peninsula, which was to be car- ried on by slowly extending conquests until 1492, when Granada, the last Mohammedan stronghold, fell. 1 The king of Prussia still has, among other titles, that of Margrave of Bran- denburg. The German word Mark is often used for " march " on maps of Germany. The English and French title is " Marquis." 2 The Mohammedan caliphate broke up in the eighth century, and the ruler of Spain first assumed the title of emir (about 756) and later (929) that of caliph. The latter title had originally been enjoyed only by the head of the whole Arab empire, who had his capital at Damascus, and later at Bagdad (see above, p. 364).
