This plan of succession, as may be supposed, failed to work peaceably; and, in 942, Kennedy, the father of the famous Brian Boroimhe, contested the sovereignty with the Eoghanist prince, Callaghan Cashel, but yielded in a chivalrous spirit, not very common under such circumstances, and joined his former opponent in his contests with the Danes.

The author of the _Wars of the Gaedhil with the Gall_ gives a glowing account of the genealogy of Brian and his eldest brother, Mathgamhain.

They are described as "two fierce, magnificent heroes, the two stout, able, valiant pillars," who then governed the Dalcassian tribes; Mathgamhain (Mahoun) being the actual chieftain, Brian the heir apparent.

A guerilla war was carried on for some time in the woods of Thomond, in which no quarter was given on either side, and wherein it was "woe to either party to meet the other." Mahoun at last proposed a truce, but Brian refused to consent to this arrangement.

He continued the war until he found his army reduced to fifteen men.