Edmund II (d. 1016), known as “Ironside” for his stout defence of the realm, king of England (1016), was in his early twenties when accepted as successor to his father Ethelred the Unready in April 1016 and set about continuing the kingdom’s defence against the Danish king, Canute, who had invaded England in the last year of his father’s reign.
He managed to save London but was defeated in Essex in the autumn. The campaign was partly successful in that Canute agreed on a treaty in which the kingdom would be partitioned, with Edmund retaining Wessex; and each would succeed to the throne of England if the other died. Edmund died of unknown causes on 30th November that year, and Canute became king of England.
Reference: “Anglo-Saxon Chronicle” trans. Anne Savage