The young Ceolred dramatically collapses and dies in 716 after going into a crazed frenzy at a banquet; in a letter to Ceolred's successor, Æthelbald, Winfird (later Saint Boniface) explained this as demon possession and claims that, in his madness, Ceolred died "cursing the priests of God".

Æthelbald, the son of Alweo, and a grandson of Eowa, brother of Penda, had spent his early years exiled from Mercia, according to the Life of Guthlac of Crowland, who often provided him and his followers shelter.

On Ceolred's death, he returns to become king, succeeding to the rule of all the Midlands and to the control of Essex.