Egbert (771/775–839), also spelled Ecgberht, Ecgbert, or Ecgbriht, was King of Wessex from 802 until his death in 839. His father was Ealhmund of Kent. In the 780s Egbert was forced into exile by Offa of Mercia and Beorhtric of Wessex, but on Beorhtric's death in 802 Egbert returned and took the throne.
Little is known of the first 20 years of Egbert's reign, but it is thought that he was able to maintain the independence of Wessex against the kingdom of Mercia, which at that time dominated the other southern English kingdoms. In 825 Egbert defeated Beornwulf of Mercia, ended Mercia's supremacy at the Battle of Ellandun, and proceeded to take control of the Mercian dependencies in southeastern England. In 829 Egbert defeated Wiglaf of Mercia and drove him out of his kingdom, temporarily ruling Mercia directly. Later that year Egbert received the submission of the Northumbrian king at Dore. The Anglo-Saxon Chronicle subsequently described Egbert as a bretwalda, or "Ruler of Britain".
Egbert was unable to maintain this dominant position, and within a year Wiglaf regained the throne of Mercia. However, Wessex did retain control of Kent, Sussex, and Surrey; these territories were given to Egbert's son Æthelwulf to rule as a subking under Egbert. When Egbert died in 839, Æthelwulf succeeded him; the southeastern kingdoms were finally absorbed into the kingdom of Wessex after Æthelwulf's death in 858.
