In the year 955, Donald O'Neill, son of the brave and beloved Murkertach, was recognised as Ard-Righ, by the required number of Provinces, without recourse to coercion. But it was _not_ to be expected that any Ard-Righ should, at this period of his country's fortunes, reign long in peace. War was then the business of the King; the first art he had to learn, and the first to practise. Warfare in Ireland had not been a stationary science since the arrival of the Norwegians and their successors, the Danes. Something they may have acquired from the natives, and in turn the natives were not slow to copy whatever seemed most effective in their tactics. Donald IV. was the first to imitate their habit of employing armed boats on the inland lakes. He even improved on their example, by carrying these boats with him overland, and launching them wherever he needed their co-operation; as we have already seen him do in his expedition against Breffni, while _Roydamna_, and as we find him doing again, in the seventh year of his reign, when he carried his boats overland from Armagh to West-Meath in order to employ them on Loch Ennell, near Mullingar. He was at this time engaged in making his first royal visitation of the Provinces, upon which he spent two months in Leinster, with all his forces, coerced the Munster chiefs by fire and sword into obedience, and severely punished the insubordination of Fergal O'Ruarc, King of Connaught. His fleet upon Loch Ennell, and his severities generally while in their patrimony, so exasperated the powerful families of the Southern Hy-Nial (the elder of which was now known as O'Melaghlin), that on the first opportunity they leagued with the Dublin Danes, under their leader, Olaf "the Crooked" (A.D. 966), and drove King Donald out of Leinster and Meath, pursuing him across Slieve-Fuaid, almost to the walls of Aileach. But the brave tribes of Tyrconnell and Tyrowen rallied to his support, and he pressed south upon the insurgents of Meath and Dublin; West-Meath he rapidly overran, and "planted a garrison in every cantred from the Shannon to Kells," In the campaigns which now succeeded each other, without truce or pause, for nearly a dozen years, the Leinster people generally sympathised with and assisted those of West-Meath, and Olaf, of Dublin, who recruited his ranks by the junction of the Lagmans, a warlike tribe, from Insi-Gall (the Hebrides). Ossory, on the other hand, acted with the monarch, and the son of its Tanist (A.D. 974) was slain before Dublin, by Olaf and his Leinster allies, with 2,600 men, of Ossory and Ulster. The campaign of 978 was still more eventful: the Leinster men quarrelled with their Danish allies, who had taken their king captive, and in an engagement at Belan, near Athy, defeated their forces, with the loss of the heir of Leinster, the lords of Kinsellagh, Lea and Morett, and other chiefs. King Donald had no better fortune at Killmoon, in Meath, the same