From An Illustrated History of Ireland by Margaret Anne Cusack
« start... Chapter XIII. ...continued
The sovereignty of Munster had also been settled on the alternate principle, between the great tribe of Dalcassians, or north Munster race, and the Eoghanists, or southeners. 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. Mahoun then sent for him. An interview took place, which is described in the form of a poetic dialogue, between the two brothers. Brian reproached Mahoun with cowardice; Mahoun reproached Brian with imprudence. Brian hints broadly that Mahoun had interested motives in making this truce, and declares that neither Kennedy, their father, nor Lorcan, their grandfather, would have been so quiescent towards the foreigners for the sake of wealth, nor would they have given them even as much time as would have sufficed to play a game of chess  on the green of Magh Adhair. Mahoun kept his temper, and contented himself with reproaching Brian for his recklessness, in sacrificing the lives of so many of his faithful followers to no purpose. Brian replied that he would never abandon his inheritance, without a contest, to "such foreigners as Black Grim Gentiles."
The result was a conference of the tribe, who voted for war, and marched into the country of the Eoghanists (the present co. Kerry), who at once joined the standard of the Dalcassians. The Danes suffered severely in Munster. This aroused the Limerick Danes; and their chieftain, Ivar, attacked the territory of Dal-Cais, an exploit in which he was joined, to their eternal shame, by several native princes and tribes, amongst whom were Maolmuadh (Molloy), son of Braun, King of Desmond, and Donabhan (Donovan), son of Cathal, King of Ui Cairbhri. The result was a fierce battle at Sulcoit, near Tipperary, wherein the Danes were gloriously defeated. The action was commenced by the Northmen. It continued from sunrise till mid-day, and terminated in the rout of the foreigners, who fled "to the ditches, and to the valleys, and to the solitudes of the great sweet flower plain," where they were followed by the conquerors, and massacred without mercy.
 Chess.—Flann Sionna, Monarch of Ireland, had encamped on this plain, and ostentatiously commenced a game of chess as a mark of contempt for the chieftains whose country he had invaded. His folly met its just punishment, for he was ignominiously defeated. See Wars of the Gaedhil, p. 113, note.