Cnut's invasion of England: setting the scene for the Norman conquest

After years of raiding England, Svein knew enough about the English political situation to exploit its weaknesses: Æthelred's court was fractured by internal rivalries, a poisonous atmosphere attributed to the influence of his untrustworthy advisor Eadric, and Svein was able to make a strategic alliance with some of those who had fallen from the king's favour.

The invasion progressed with devastating speed: within a few weeks all the country north of Watling Street – the ancient dividing-line between the north and south of England – had submitted to the Danish king. Next the south was subdued by violence, and before the end of the year Æthelred and his family had been forced to flee to Normandy.

Svein, now king of England and Denmark, ruled from Christmas to Candlemas, but died suddenly on 3 February 1014. The Danish fleet chose Cnut to succeed him, but the English nobles had other ideas: they contacted Æthelred, still in refuge in Normandy, and invited him to come back as king.

They said, the Anglo-Saxon Chronicle tells us, “that no lord could be dearer to them than their natural lord, if he would govern more justly than he had done before”. In response, Æthelred promised to be a better king, to forgive those who had deserted him, and to “remedy all the things of which they disapproved”. On these terms the agreement was made, and Æthelred returned to England. This time he managed to drive out Cnut, and the fleet went back to Denmark.

But a year later the young Danish king was back, hoping to repeat his father’s conquest. Despite his promises, Æthelred did not forgive those who had sided with the Danes: he viciously punished the northern leaders who had made an alliance with Svein, and in doing so caused his son, Edmund Ironside, to rebel against him. When Cnut returned in 1015, Æthelred was ill and England was divided: large parts of the country submitted to the Danes, while Edmund struggled to put an army together.

Only after Æthelred died in April 1016 did southern England finally unite behind Edmund, and six months of war followed, with the two armies fighting battles all over the south.

The last was fought at a place called Assandun in Essex on 18 October 1016 – by strange coincidence, 50 years almost to the day before the battle of Hastings – and there the Danes were victorious. Edmund died six weeks later (likely by wounds received in battle or by disease, but some sources say he was murdered), and Cnut was finally sole king of England.

The immediate aftermath of Cnut's conquest was violent, although not much more so than the last years of Æthelred's reign. Potential opponents were summarily killed, and the remaining members of the royal family were driven into exile. Cnut married Æthelred's widow, Emma, sister of the duke of Normandy, and between them they founded a new dynasty – part Danish, part Norman, but presenting itself as English. There had been Danish kings ruling in England before, some of them famous Vikings whose names were still something to conjure with in the 11th century: Cnut's poets, extolling his conquest in Old Norse verse, compared him to the fearsome Ivar the Boneless and the sons of Ragnar Lothbrok, and in one sense, Cnut was heir to the conquests of these larger-than-life Danish kings.

But at the same time Cnut presented himself as a conciliatory conqueror, eager to learn from the land he had captured: by gifts to churches and monasteries he made amends for the damage his father and previous Danish kings had done, and he ruled in English and through English laws – even as his poets praised him for driving Æthelred's family out of England. When he made a diplomatic visit to Rome in 1027, he was welcomed as the Christian ruler of a new North Sea empire. Almost the only thing many people know about Cnut is that he made a grand display of his inability to control the tide, and this story – first recorded in the 12th century – is not quite as silly as it is sometimes assumed to be: power over the sea was the very basis of Cnut's authority, and a story in which Cnut yields that sea-power to God might have helped to explain the remarkable transformation of a Viking king into a Christian monarch.

When Cnut died in 1035, after ruling for nearly 20 years, he was buried in Winchester, the traditional seat of power of the kings of Wessex. His empire did not long survive him. After the early death of Harthacnut, Cnut’s son by Emma, Æthelred's son Edward (later Edward the Confessor) regained the English throne – “as was his natural right”, the Anglo-Saxon Chronicle says. During his reign Edward had to deal with those, like Earl Godwine and his sons, who had risen to power under Cnut, but before long the impact of the Danish Conquest was to be overshadowed by the second, more famous conquest of the 11th century.

Compared to the Norman victory in 1066 – perhaps the single most famous date in medieval English history – the Danish Conquest has always seemed less important, with few enduring consequences. But the story of Svein’s well-planned invasion and Cnut’s successful reign tells us some interesting things about regional divisions within England, and England’s relationship with Scandinavia and the rest of Europe in the 11th century: in many ways – not least by destabilising the English monarchy and driving Edward into exile in Normandy – the Danish Conquest set the stage for much of what happened in 1066.

Dr Eleanor Parker is Mellon Postdoctoral Fellow in Anglo-Norman England at the University of Oxford. You can follow her on Twitter @ClerkofOxford