Æthelberht was the King of Wessex from 860 until his death in 865. He was the third son of King Æthelwulf by his first wife, Osburh. Æthelberht was first recorded as a witness to a charter in 854. The following year Æthelwulf went on pilgrimage to Rome and appointed his oldest surviving son, Æthelbald, as king of Wessex while Æthelberht became king of the recently conquered territory of Kent. Æthelberht may have surrendered his position to his father when he returned from pilgrimage, but resumed the south-eastern kingship when his father died in 858.

Æthelwulf was King of Wessex from 839 to 858. In 825, his father, King Ecgberht, defeated King Beornwulf of Mercia, ending a long Mercian dominance over Anglo-Saxon England south of the Humber. Ecgberht sent Æthelwulf with an army to Kent, where he expelled the Mercian sub-king and was himself appointed sub-king. After 830, Ecgberht maintained good relations with Mercia, and this was continued by Æthelwulf when he became king in 839, the first son to succeed his father as West Saxon king since 641.