Murkertach, or Murtogh O'Brien, was of nearly the same age as his rival, and his equal, if not superior in talents, both for peace and war. During the last years of his father's reign and illness, he had been the real ruler of the south, and had enforced the claims of Cashel on all the tribes of Leath Mogha, from Dublin to Galway. In the year 1094, by mutual compact, brought about through the intercession of the Archbishop of Armagh and the great body of the clergy, north and south—and still more perhaps by the pestilence and famine which raged at intervals during the last years of the eleventh century—this ancient division of the midland _asker_, running east and west, was solemnly restored by consent of both parties, and Leath Mogha and Leath Conn became for the moment independent territories. So thoroughly did the Church enter into the arrangement, that, at the Synod of Rath-Brazil, held a few years later, the seats of the twelve Bishops of the southern half were grouped round the Archbishop of Cashel, while the twelve of the northern half were ranged round the Archbishop of Armagh. The Bishops of Meath, the ancient mensal of the monarchy, seem to have occupied a middle station between the benches of the north and south. Notwithstanding the solemn compact of 1094, Murtogh did not long cease to claim the title, nor to seek the hostages of all Ireland. As soon as the fearful visitations with which the century had closed were passed over, he resumed his warlike forays, and found Donald of Aileach nothing loath to try again the issue of arms. Each prince, however, seems to have been more anxious to coerce or interest the secondary chiefs in his own behalf than to meet his rival in the old-style pitched battle. Murtogh's annual march was usually along the Shannon, into Leitrim, thence north by Sligo, and across the Erne and Finn into Donegal and Derry. Donald's annual excursion led commonly along the Bann, into Dalriada and Ulidia, Whence by way of Newry, across the Boyne, into Meath, and from West-Meath into Munster. In one of these forays, at the very opening of the twelfth century, Donald surprised Kinkora in the absence of its lord, razed the fort and levelled the buildings to the earth. But the next season the southern king paid him back in kind, when he attacked and demolished Aileach, and caused each of his soldiers to carry off a stone of the ruin in his knapsack. "I never heard of the billeting of grit stones," exclaims a bard of those days, "though I have heard of the billeting of soldiers: but now we see the stones of Aileach billeted on the horses of the King of the West!"