The government of the realm passed into the hands of the great nobles who upheld aethelred, and Dunstan withdrew powerless to Canterbury, where he died nine years later.
During the eleven years from 979 to 990, when the young king reached manhood, there is scarcely any internal history to record. New danger however threatened from abroad. The North was girding itself for a fresh onset on England. The Scandinavian peoples had drawn together into their kingdoms of Denmark, Sweden, and Norway; and it was no longer in isolated bands but in national hosts that they were about to seek conquests in the South. The seas were again thronged with northern freebooters, and pirate fleets, as of old, appeared on the English coast. In 991 came the first burst of the storm, when a body of Norwegian Wikings landed, and utterly defeated the host of East Anglia on the field of Maldon. In the next year aethelred was forced to buy a truce from the invaders and to suffer them to settle in the land; while he strengthened himself by a treaty of alliance with Normandy, which was now growing into a great power over sea. A fresh attempt to expel the invaders only proved the signal for the gathering of pirate-hosts such as England had never seen before, under Swein and Olaf, claimants to the Danish and Norwegian thrones.
Their withdrawal in 995 was followed by fresh attacks in 997; danger threatened from Normans and from Ost-men, with wikings from Man, and northmen from Cumberland; while the utter weakness of the realm was shown by aethelred's taking into his service Danish mercenaries, who seem to have been quartered through Wessex as a defence against their brethren. Threatened with a new attack by Swein, who was now king, not only of Denmark, but by the defeat and death of Olaf, of Norway itself, aethelred bound Normandy to his side by a marriage with its duke's sister Emma. But a sudden panic betrayed him into an act of basest treachery which ruined his plans of defence at home. Urged by secret orders from the king, the West-Saxons rose on St. Brice's day and pitilessly massacred the Danes scattered among them. Gunhild, the sister of their king Swein, a Christian convert, and one of the hostages for the peace, saw husband and child butchered before her eyes ere she fell threatening vengeance on her murderers. Swein swore at the news to wrest England from aethelred. For four years he marched through the length and breadth of southern and eastern England, "lighting his war-beacons as he went" in blazing homestead and town. Then for a heavy bribe he withdrew, to prepare for a later and more terrible onset.
But there was no rest for the realm. The fiercest of the Norwegian jarls took his place, and from Wessex the war extended over East Anglia and Mercia. Canterbury was taken and sacked, aelfheah the Archbishop dragged to Greenwich, and there in default of ransom brutally slain. The Danes set him in the midst of their husting, pelting him with stones and ox-horns, till one more pitiful than the rest clave his skull with an axe.
But a yet more terrible attack was preparing under Swein in the North, and in 1013 his fleet entered the Humber, and called on the Danelaw to rise in his aid. Northumbria, East Anglia, the Five Boroughs, all England north of Watling Street, submitted to him at Gainsborough. aeihehed shrank into a King of Wessex, and of a Wessex helpless before the foe. Resistance was impossible. The war was terrible but short. Everywhere the country was pitilessly harried, churches plundered, men slaughtered. But with the one exception of London, there was no attempt at defence. Oxford and Winchester flung open their gates. The thegns of Wessex submitted to the northmen at Bath. Even London was forced at last to give way, and.aethelred fled over sea to a refuge in Normandy. With the flight of the king ended the long struggle of Wessex for supremacy over Britain. The task which had baffled the energies of Eadwine and Offa, and had proved too hard for the valour of Eadward and the statesmanship of Dunstan, the task of uniting England finally into a single nation, was now to pass, to other hands.