Æthelred makes an alliance with Normandy in 1001, through marriage to the Duke's daughter Emma, in the hope of strengthening England.

He now makes a great error: in 1002 he orders the massacre of all the Danes in England, which has serious consequences.

It angers Sweyn, who unleashes a decade of devastating attacks on England.

Northern England, with its sizable Danish population, sides with Sweyn.

By 1013, London, Oxford, and Winchester have fallen to the Danes.

Æthelred flees to Normandy and Sweyn seizes the throne.

Sweyn suddenly dies in 1014, and Æthelred returns to England, confronted by Sweyn's successor, Cnut.

However, in 1016, Æthelred also suddenly dies.

Cnut swiftly defeats the remaining Saxons, killing Æthelred's son Edmund in the process.

Cnut seizes the throne, crowning himself King of England.