In 750 Eadberht is said to have annexed a large part of Ayrshire to his kingdom.
Eadberht showed considerable independence in his dealings with the church, and his brother Ecgberht, to whom the well-known letter of Bede is addressed, was from 734 to 766 archbishop of York.
In 758 Eadberht resigned the kingdom to his son Oswulf, and became a monk.
Moll JEthelwald, who may have been a brother of Eadberht, succeeded, and after a victory over a certain Oswine, who fell in the battle, abdicated and became a monk probably under compulsion in 765.
Towards the middle of the 8th century Strathclyde was again threatened by an alliance between the Northumbrians and Picts, and in 750 the Northumbrian king Eadberht wrested from them a considerable part of their territories in the west including Kyle in Ayrshire.
A grant, dated by Birch about 725, is made by Nunna to Eadberht, bishop of Selsey, and to this too "Uuattus" appears as a witness.
In 798 he invaded Kent, deposed and imprisoned Eadberht Pra n, and made his own brother Cuthred king.