The Battle of Assandun

Edmund Ironside meets King Canute (Matthew Paris)

Fifty years before the Norman Invasion changed the culture of Britain, the island (or parts of it) changed hands, from the English to the Danes. The Battle of Assandun, on 18 October 1016, was the last phase of the Danes' attempt to re-take Britain.

It was a signifiant enough event that accounts made it into several chronicles. The Anglo-Saxon Chronicle goes into great detail:

A.D. 1016.  This year came King Knute with a marine force of one hundred and sixty ships, and Alderman Edric with him, over the Thames into Mercia at Cricklade; whence they proceeded to Warwickshire, during the middle of the winter, and plundered therein, and burned, and slew all they met.

Edmund Ironside was king; his son, Edmund Ætheling, tried to gather an army, but not everyone answered the call.

Then began Edmund the etheling to gather an army, which, when it was collected, could avail him nothing, unless the king were there and they had the assistance of the citizens of London.  The expedition therefore was frustrated, and each man betook himself home.

Eventually an army was assembled, but ultimately Cnut won. Edmund Ironside was forced to sign a treaty agreeing that Cnut would control all of England except Wessex, and that whichever died first would cede all his territory to the other, the survivor's son becoming the heir to all England.

Mere weeks after signing the treaty, Edmund Ironside died on 30 November 1016. Cnut became king of all England, which he ruled for the following 20 years.