821. Coenwulf of Mercia dies
Ceolwulf, Cenwulf's brother, succeeds to Mercia
The Anglo-Saxon Chronicle records Coenwulf's death without details. It is in the 12th-century historical poem L'Estoire des Engleis of Geffrei Gaimar that we learn that he died at Basingwerk, at the north end of Wat's Dyke (Stenton, p.230, says this is unlikely to be invention and suggests it may come from a lost version of the Chronicle possessed by Gaimar).
Charters of Ceolwulf calling him the king of the Mercians and the people of Kent show that Ceolwulf retained control of Kent. The East Angles revolted briefly (q.v.), but the rebellion was quashed. Ceolwulf conquered Powys in 822, but was himself deposed in 823.
F. Stenton, Anglo-Saxon England, 3rd edn (Oxford: 1971)