"Rule Britannia! Britannia rule the waves.
Britons never, never, never shall be slaves."
In 1016, the English and Danish armies met at Assandun, where Canute the Great defeated Edmund Ironside and took control of England. This led to a period where the Danes controlled England that lasted until 1042. The Normans conquered England 20 years later. However, there was a battle that the English lost that could have been won. Eadric Streona, an Englishman, abandoned his countrymen and the battle was lost.
- "But the traitorous ealdorman, Edric Streona, seeing that the Danish line was giving way, and that the English were getting the victory, kept the promise which he had previously made to Canute, and fled with the Magesetas [Magonsæte], and that division of the army which he commanded; thus craftily circumventing his lord king Eadmund and the English army, and by his craft throwing the victory into the hands of the Danes."
- —John of Worcester
If Eadric Streona had instead been loyal to Edmund, the Danes would have lost the battle. Canute the Great dies in the battle after the Danish lines were broken and his army is scattered. His kingdoms go to war against each other to determine who is his rightful successor, giving the English the power to expel the Danes from Britain.
Welcome to the Rule, Britannia! timeline.