Dictionary of National Biography, 1885-1900/Adda
ADDA (d. 565), king of Bernicia, the eldest son of Ida, founder of the Anglian kingdom of Bernicia, succeeded his father in 559, and, according to Nennius, reigned eight years. Simeon of Durham and the Chronologia, prefixed to Bishop More's MS. of Bæda, place the reign of Glappa lasting for one year between the reigns of Ida and Adda. The Genealogia in the Appendix to Florence of Worcester makes Adda reign for seven years after the death of his father, and puts Clappa (Glappa) after him. The early Northumbrian chronology is confused and uncertain (see Mon. Hist. Brit. p.75 note). The gradual conquest made by the Bernicians, in which at one time the invaders and at another the natives were victorious, must have made the reign of Adda full of fighting. He died in 565. The name Adda may probably be discerned in conjunction with the patronymic syllable ing in Addington.
[Nennius; Simeon of Durham; App. to Florence of Worcester; Mon. Hist. Brit. 74, 75, 290, 524.]