Charlemagne was at this time over sixty years of age. His white hair and beard added to his majestic appearance. His fourth wife had recently died, and he now, upon suggestions from Rome, considered a union with the Empress Irene of Greece. The real nefariousness of this woman was not revealed until later; and at this time the Emperor knew no reason why he should not marry her. But it is to be remembered that in every action Charlemagne conducted himself not as a private person, but as the ruler of a great empire. The only question which arose in his mind was whether such a union would accrue to the advantage of the Christian world and his own people. He decided that it would, and entered upon the preliminaries of a settlement. Then came news of the dethronement of Irene and her banishment to Lesbos—an event which was subsequently justified and which proved to be very fortunate for him. An agreement was made with the Saxons in the year 803 at Selz on the Saale, which secured peace for the future. In consideration of the restoration of their old rights and customs they promised to refrain from any resistance to the spread and maintenance of Christianity in Saxony, and to accept the incorporation of their country as part of the Frankish Empire. In 808 the aged hero again took the field. He led an expedition against Gottfried, King of Denmark, who in years past had been so busy inciting Saxon revolt. But the Emperor’s purpose was not to obtain satisfaction for old offences, but to stamp out new hostilities. The Obotrites, allies of the Franks, had been suddenly attacked by Gottfried; Danish vessels had harried the German coast; and the Danes had made several landings and pillaged and murdered. Driven back by Carl, the Emperor’s oldest son, Gottfried reached a spot several miles beyond the Schley, where a wall had been constructed across the country, still known as the “Danewerk.” During this expedition the Emperor was thrown from his horse, which caused his lance to fly from his hand, and his sword to drop from his belt. Many regarded this as an unfortunate omen; but Gottfried and Charlemagne did not meet on the field. Gottfried was slain by some of his own people, and Hemming, his brother and successor, hastened to send a peace embassy to Charlemagne. A treaty was negotiated by which Denmark renounced all claim upon the territory for which it had striven, south of the Eider, which was recognized as the northern boundary of the Frankish Empire. When Charlemagne returned to Aix-la-Chapelle he was taken ill for the first time in his life. He regarded his ailment, however, as nothing worse than a slight feverish attack, and resumed his official duties in a few days. For the first time his people began to realize that he was mortal, and to ask themselves what might happen to the Empire if he were taken away.