Ecgberht, the man destined to secure the union of all the Saxon and Angle kingdoms, mounted the throne of Wessex in 802. He had spent a long period of exile from his native land, at the court of Charles the Great, where he received his political and military training. After a quarter of a century of inactivity, broken only by short wars with the Britons, the opportunity of uniting England, came at last. A defeat of the Mercians in the invasion of Wessex in 825, encouraged the subject kingdoms of the former to rise in rebellion. Weakened by two years of warfare and defeated by East Anglia, Mercia yielded without a struggle to Ecgberht, when the latter invaded the kingdom in 827. A year later Ecgberht advanced north into Northumbria and the ancient center and seat of power in England welcomed the rule of the southern conqueror as an escape from the anarchy of the past century. With this submission of Northumbria, the period of the various Saxon kingdoms ended. The time had passed when Anglo-Saxon, shut off from intercourse with the rest of the world, was to wear out his energy in internecine warfare and intrigue. From now on the scope of his activities was to constantly expand. The conflicts between Mercia, Northumbria and West Saxon were to be superseded by those of the English with the Dane and Norman.