Æthelred II, who had earlier been stricken ill, died on April 23, 1016. Edmund succeeded to the throne and mounted a last-ditch effort to revive the defence of England. While the Danes laid siege to London, Edmund headed for Wessex, where he gathered an army. When the Danes pursued him he fought them to a standstill. He then raised a renewed Danish siege of London and won repeated victories over Canute. However, on October 18 Canute decisively defeated him at the Battle of Ashingdon in Essex. After the battle the two kings negotiated a peace in which Edmund kept Wessex while Canute held the lands north of the River Thames. In addition, they agreed that if one of them should perish, territories belonging to the deceased would be ceded to the living.
On November 30, 1016, King Edmund II died in Oxford or London, and his territories were ceded to Canute who then became king of England. Legend has it that soldiers acting in favor of Canute hid beneath a lavatory and thrust a sword up Edmund's posterior when he sat down to relieve himself, resulting in his death. Edmund was buried at Glastonbury Abbey in Somerset. His burial site is now lost. During the Dissolution of the Monasteries any remains of a monument or crypt were destroyed and the location of his body is unknown.