April 23, 1016. Æthelred dies
Edmund Ironside chosen as king by London, and besieged there
Cnut chosen as king by the rest of England at Southampton (?)
Edmund retakes Wessex
Battles of Penselwood, Sherston, Brentford -- Eadric switches sides
The Anglo-Saxon Chronicle notes that Æthelred died on St George's day (April 23), and that after that Edmund was chosen as king by all the counsellors who were in London. The allegiance of the rest of the country is not discussed in the Chronicle, but John of Worcester in the 12th century explains that the chief nobles of the rest of the country renounced the line of Æthelred and concluded a peace with Cnut at Southampton. The facts that in the Chronicle's account the Vikings could besiege Edmund in London with impunity, and that Edmund had to re-take possession of Wessex, tend to support John of Worcester's statement.
Edmund did break out of London and take back Wessex, and receive the submission of the West Saxons. Shortly afterwards he fought Cnut's army at Penselwood near Gillingham, and then again after midsummer at Sherston -- the Chronicle notes that in the battle of Sherston Eadric Streona and Ælfmær Darling were supporting the Danes. Edmund then gathered the West Saxon army and took them to London and relieved the siege and sent the Danes back to their ships. Two days later, Edmund fought the Danes at Brentford and put them to flight, and then he returned to Wessex and collected his army.
Once Edmund had left the Danes besieged London again, but they were successfully repulsed, and went instead into Mercia, and ravaged there, and gathered again in the Medway. Edmund brought his army to Kent, and fought the Danes at Otford according to John of Worcester, and the Danes fled to Sheppey. Eadric switched back to Edmund's side at Aylesford, and the Chronicle records Edmund's acceptance with the doleful comment, "no greater folly was ever agreed to than that was". The Danes meanwhile went back inland into Essex. Edmund overtook them in Essex at the hill called Ashingdon, and fought them there on October 18.
The fate of the other members of Æthelred's family after his death in April 1016 is less certain. A contemporary German observer, Thietmar of Merseburg, records that Emma and her two sons were in besieged London, and that the Danes offered Emma peace if she would give up her sons and pay an appropriate ransome. Thietmar adds that after long deliberation Emma agreed to this, but in the confusion the two brothers slipped away. Later Norse sources credit Edward (the future Confessor) with fighting alongside Edmund Ironside in the battles of 1016, though his presence was probably only symbolic (he can have been no more than 13 years old, since his parents were married in 1002). Edward makes no impression on the contemporary English sources, and a charter he witnesses at Ghent at Christmas 1016 suggests that he was in Flanders by the end of 1016, perhaps on his way back to Normandy after Edmund's death and Cnut's triumph in November 1016. It is uncertain where the other children of Æthelred and Emma (Alfred and Godgifu) were in the course of 1016, but all three of them were in Normandy after 1016 (see further entry on 1033/4).
F. Barlow, Edward the Confessor, 2nd edn (London: 1997)
S. Keynes, "The Æthelings in Normandy", Anglo-Norman Studies 13 (1991), pp.173-205