Of his boyhood we know as little as of his birth, but he seems at an early age to have mingled in the real business of life, for when only twelve years old we find him despatched to receive and welcome the sovereign pontiff who came to implore his father's aid against the barbarians that threatened Rome. From the usual habits of the Franks, it is also probable that he accompanied Pepin in his campaigns at an early age; but the first time that we really see him in the field, is on the renewal of the war with the rebellious Duke of Aquitaine. [Illustration: Charlemagne.] Upon the death of Pepin, 768, Charlemagne and his younger brother, Carloman, succeeded to equal portions of one of the most powerful European kingdoms, bounded by the Pyrenees, the Alps, the Mediterranean, and the ocean. But this would hardly have enabled the monarchs, even had they been united, to resist successfully the incursions of the barbarous tribes on the German frontiers of France, which had commenced with the first establishment of the Frankish dominion in Gaul; and which was kept alive by the constant pouring out of fresh hordes from the overpopulated North. The situation of Charlemagne was rendered yet more perilous by the passive enmity of his brother, and the rebellion of Hunald, the turbulent Duke of Aquitaine. But fortunately, Charlemagne had a genius equal to the difficulties of his situation; though his brother refused to aid him, he defeated Hunald; and no less illustrious by his clemency than by his valor and military skill, he forgave the vanquished rebel. Desiderius, the king of Lombardy, had made large encroachments upon the states of the Roman pontiff, whose cause was taken up by Charlemagne. This led to feuds, which Bertha, the mother of the Frankish king, endeavored to appease by bringing about a union between her son and the daughter of the Lombard. But Charlemagne soon took a disgust to the wife thus imposed upon him, and repudiated her, that he might marry Hildegarde, the daughter of a noble family in Suabia.