King Edmund II Ironside's reign was marked by conflict with the Danish invaders led by Sweyn Forkbeard. Sweyn had invaded England in 1013, and by 1015, much of the country had been conquered by the Danes. Æthelred the Unready, Edmund's father, had been driven into exile, and the Witenagemot, the Anglo-Saxon council of elders, elected Edmund as king in April 1016.

During his brief reign, Edmund was able to reclaim some of the territories that had been lost to the Danes and won several notable victories against them, including the Battle of Brentford. However, he was ultimately unable to defeat Sweyn, and in November 1016, the two kings agreed to divide England between them, with Edmund ruling the southern and eastern parts of the country and Sweyn the north and west. However, the peace between them did not last long, and Sweyn soon broke the treaty and continued to press his claim to the entire kingdom. In November 1016, Edmund died, possibly of natural causes, and Sweyn became the undisputed king of England. Edmund's death marked the end of the Danish line of kings in England and the return of the Saxon dynasty with the coronation of King Cnut. Edmund's reign was brief and marked by conflict, but his military successes against the Danes were significant and his death marked a turning point in the Danish invasions and the start of the Danish reign in England.