 All these territories would be lost to the Uí Néill in the following century.The date of the battle of Mag Femen is given as 446 in the Annals of Ulster and 447 in the Annals of Inisfallen.However, Devane (p. 189, 2005) proposes that the date has been misplaced, as a result of ""the original source of the entries being wrongly entered by one, if not indeed two, cycles in the Irish 84-year cycle, by the which the Irish and British churches until the sixth century reckoned the date of Easter.