Adda was one of several sons born to Ida, the first ruler of Bernicia, as was his successor Æthelric.
Adda may have been the Bernician commander at the battle of Caer Greu, where the British kings Peredur and Gwrgi of Ebrauc were killed.
The Annales Cambriae state that the Battle of Caer Greu took place in 580.
The evidence for Adda being the Bernician king in question is that the Welsh Triads identify that leader as Ida.
The earliest authorities differ widely on the order and the regnal years of the Bernician kings between the death of Ida and the beginning of Æthelfrith's rule in 592/593.