Edmund, the son of Ethelred the Unready and half-brother of Edward the Confessor, was born in about 981. In 1015 he defied his father by marrying the widow of a Danish earl in Mercia.

When Canute the Great invaded England in 1015, Edmund raised an army in Mercia and when his father died in April 1016, he was chosen as king by the people of London, however, the Witan selected Canute. After a series of battles, where he obtained the nickname, Ironside, Edmund was defeated at Ashingdon in Essex.

After negotiations, Canute the Great agreed that Edmund could continue to control Wessex. Edmund Ironside died a few months later in November 1016.