 Edmund's reign was marred by a war he had inherited from his father; his cognomen "Ironside" was given to him "because of his valour" in resisting the Danish invasion led by Cnut the Great.Edmund was not expected to be King of England; however, by June 1014 two elder brothers had died, making him heir apparent.England was conquered by Sweyn Forkbeard at the end of the same year, but he died shortly thereafter, paving the way for Æthelred to return to the throne, which he did, but not without opposition.