 Conchobor son of Donnchad invaded Brega and camped at Gualu.He invaded southern Brega again and a vast number of the men of southern Brega fell by him, and the Uí Chernaig submitted under compulsion.Murchad had Cumuscach son of Tuathal, king of Ard Ciannachta assassinated in 822 probably in retaliation for his failure.