Charles the Great died in the year 814. A short time before his death, he sent for his son Lewis, and in the great church at Aix-la-Chapelle, which was Charles's favourite place of abode, he took from the altar a golden crown, and with his own hands placed it on the head of Lewis. By this he meant to show that he did not believe the empire to depend on the pope's will, but considered it to be given to himself and his successors by God alone. CHAPTER V. DECAY OF CHARLES THE GREAT'S EMPIRE. A.D. 814-887. Lewis, the son of Charles the Great, was a prince who had very much of good in him, so that he is commonly called the Pious. But he was of weak character, and his reign was full of troubles, mostly caused by the ambition of his own sons, who were helped by a strong party among the clergy, and even by Pope Gregory the Fourth. At one time he was obliged to undergo public penance, and some years later he was deprived of his kingdom and empire, although these acts caused such a shock to the feelings of men that he found friends who helped him to recover his power. And after his death (A.D. 840) his children and grandchildren continued to quarrel among themselves as long as any of them lived. Besides these quarrels among their princes, the Franks were troubled at this time by enemies of many kinds. First of all I may mention the Northmen, who poured down by sea on the coasts of the more civilized nations. These were the same who in our English history are called Danes, with whom the great Alfred had a long struggle, and who afterwards, under Canute, got possession of our country for a time. They had light vessels,--_serpents_, as they were called,--which could sail up rivers; and so they carried fire and sword up every river whose opening invited them, making their way to places so far off the sea as Mentz, on the Rhine; Treves, on the Moselle; Paris, on the Seine; and even Auxerre, on the Yonne. They often sacked the wealthy trading cities which lay open to their attacks; they sailed on to Spain, plundered Lisbon, passed the Straits of Gibraltar, and laid waste the coasts of Italy.