Weis' "Ancestral Roots. . ." (170:7). the following is taken from an Internet posting of Michael R. Davidson of Edinburgh. Scotland, on 23 Oct 1995:
Domnall Brecc mac Eochaid Buid
Domnall Brecc succeeded to the kingship in 629, when his predecessor and distant relative Connad Cerr was killed in Ireland after a three month reign. Domnall was either incompetent, unlucky or both; he never won a battle. His first defeat came in 635 in a battle which was possibly against the Picts. In 637 he was defeated at the battle of Mag Rath in Ireland, and from this point on the kings of Dal Riata completely lost control of their Irish possessions. It was probably about this point that Domnall was demoted to the position of joint king with his third cousin Ferchar, son of Connad Cerr. Domnall was defeated yet again, possibly by the Picts, in 638. He finally met his death in 642, at the hands of the Britons of Strathclyde, and his death was triumphantly recorded in one rescension of _Y Goddodin_, a famous seventh-century Old Welsh poem. He was succeeded by his joint king Ferchar.