A period of comparative repose followed. Many of the Danes became converts to Christian doctrine, and there was, probably, more or less of intermarriage among the higher classes of the rival races. But the Norsemen retained much of their old-time ferocity, and, occasionally, the ancient struggle for supremacy was renewed, with varying success. It is humiliating for an Irish writer to be obliged to admit that some of the Irish Christian princes, jealous of the incumbent Ard-Righ, did not remain faithful to their country, and actually allied themselves with the Danes, participating in their barbarous acts. This explains why, for a period of about three hundred years, in spite of repeated Irish victories, the Norsemen were able to hold for themselves a large portion of Ireland, especially the districts lying close to the sea, where they had no difficulty in receiving supplies and reinforcements from Denmark and Norway. Many of those old Irish princes were, indeed, conscienceless traitors, but the people, as a whole, never abandoned the national cause. The feuds of the Munster chiefs, toward the end of the tenth century, had the unlooked-for effect of bringing to the front the greatest ruler and warrior produced by ancient Ireland. Because of a series of tragedies in which the hero himself bore no blameful part, Brian of Kinkora, son of Kennedy and brother of Mahon, both of whom had reigned as kings of Thomond, or North Munster, ascended the throne of that province. Mahon, progenitor of the southern MacMahons—from whom descended the late President of the French Republic, Maurice Patrice MacMahon, Marshal of France and Duke of Magenta—was murdered by Prince Donovan, a faithless ally. His younger brother, Brian, afterward called Borumah or “Boru”—literally, “Brian of the Cow Tribute”—fiercely avenged his assassination on the treacherous Donovan, and on the Danish settlers of Limerick, who were the confederates of that criminal in his evil acts. Brian, young, powerful, and destitute of fear, after disposing of Donovan, killed with his own brave hand Ivor, the Danish prince, together with his two sons, although these fierce pagans had taken refuge in the Christian sanctuary on Scattery Island, in the Shannon, and then swept the remaining conspirators, both Irish and Danes, off the face of the earth. Prince Murrough, Brian’s heir, then a mere boy, slew in single combat the villanous chief, Molloy, who, as the base instrument of Donovan and Ivor, actually killed his uncle, King Mahon. Afterward, Brian reigned for a brief period, quietly, as King of Thomond. He had a profound insight and well knew that only a strong, centralized government could unite all Ireland against the foreigners, and he designed to be the head of such a government. He had only one rival in fame and ability on Irish soil—the reigning Ard-Righ, Malachy II. This monarch had scourged the warrior Northmen in many bloody campaigns.