CHARLES MARTEL was " the Mayor of the Palace," the viceroy of the decadent descendants of the great Merovingian house of Frankish kings who had conquered Gaul, and his son Pepin became King of the Franks (751) in name as well as in fact by the grace of Pope Stephen II. It was a step of great importance. The Pope was not yet the holder of any real temporal power, but he was recognised as the con-ferrer of any title to it. He was the head of the universal Church, a supra-national body which confessed a common religion and used Latin as its universal language. Only in the East were his claims to supremacy not admitted. The relations of the Popes, the rulers of old Rome in the absence of any other claimant, with the patriarchs of the new Rome had long been strained, and both the emperors and the patriarchs of Constantinople had shown increasing reluctance to admit the claim to headship on the part of him whom they styled the bishop of Rome. The emperors refused admission on political, the patriarchs on ecclesiastical, grounds. Quarrel succeeded quarrel, with political issues carefully concealed behind theological niceties. Matters of doctrine and discipline divided Eastern from Western Christianity, and all attempts at reconciliation proving vain, Western Christianity tended more and more to develop on its own European lines and claim universal power; the Eastern Church was abandoned to become an agency of the Byzantine Empire. But the universal Church of the West also claimed a temporal power. The Pope of Rome vindicated Rome for his own rule as the patrimony of St. Peter. He might be the Holy Father of Danes, Germans, English ; but he was also an Italian princeling, and to his principality he attached great importance. It therefore became necessary for the Pope to secure possession of his patrimony by acquiring a temporal protector, and it was this need for protection that was the reason for his arrangement with Pepin. The King of the Franks by the grace of the Pope crossed the Alps, subdued the Lombards in the north and drove the Byzantine power from the east of Italy. He had firmly consolidated his power in France, clearing the Moslems finally from the south, and in 771 left to his son Charles the greatest kingdom the West had so far known. Charles (or Karl) rightly called the Great, or Charlemagne, greatest of German and first of French kings, ascended the throne just when the West was at last able to react on the invaders who so far had threatened it. Fixing the capital of a great empire at Aachen on the Rhine, he pushed south and east with untiring energy. An invasion of Spain proved a task beyond his strength. The Pyrenees were crossed and the Moslems routed, but the disaster of Roncesvalles, where the rearguard of Charlemagne's army was cut off and destroyed, showed that conquest had been pushed beyond its limits. Spain was abandoned and the Christians of the hills took up the fight that was to end by driving the Moslem from the peninsula.