The traitors gained nothing by their treachery except the contempt of posterity.  Brian was not slow in avenging his brother.  “He was not a stone in place of an egg, nor a wisp of hay in place of a club; but he was a hero in place of a hero, and valour after valour."[211]

Public opinion was not mistaken in its estimate of his character.  Two years after the death of Mahoun, Brian invaded Donovan’s territory, drove off his cattle, took the fortress of Cathair Cuan, and slew Donovan and his Danish ally, Harolt.  He next proceeded to settle accounts with Molloy.  Cogaran is sent to the whole tribe of Ui Eachach, to know “the reason why” they killed Mahoun, and to declare that no cumhal or fine would be received, either in the shape of hostages, gold, or cattle, but that Molloy must himself be given up.  Messages were also sent to Molloy, both general and particular—­the general message challenged him to battle at Belach-Lechta; the particular message, which in truth he hardly deserved, was a challenge to meet Murrough, Brian’s son, in single combat.  The result was the battle of Belach-Lechta,[212] where Molloy was slain, with twelve hundred of his troops, both native and foreign.  Brian remained master of the field and of the kingdom, A.D. 978.

Brian was now undisputed King of Munster.  In 984 he was acknowledged Monarch of Leth Mogha, the southern half of Ireland.  Meanwhile Malachy, who governed Leth Cuinn, or the northern half of Ireland, had not been idle.  He fought a battle with the Danes in 979, near Tara, in which he defeated their forces, and slew Raguall, son of Amlaibh, King of Dublin.  Amlaibh felt the defeat so severely, that he retired to Iona, where he died of a broken heart.  Donough O’Neill, son of Muircheartach, died this year, and Malachy obtained the regal dignity.  Emboldened by his success at Tara, he resolved to attack the foreigners in Dublin; he therefore laid siege to that city, and compelled it to surrender after three days, liberated two thousand prisoners, including the King of Leinster, and took abundant spoils.  At the same time he issued a proclamation, freeing every Irishman then in bondage to the Danes, and stipulating that the race of Nial should henceforth be free from tribute to the foreigners.

It is probable that Brian had already formed designs for obtaining the royal power.  The country resounded with the fame of his exploits, and Malachy became aware at last that he should either have him for an ally or an enemy.  He prudently chose the former alternative, and in the nineteenth year of his reign (997 according to the Four Masters) he made arrangements with Brian for a great campaign against the common enemy.  Malachy surrendered all hostages to Brian, and Brian agreed to recognize Malachy as sole Monarch of northern Erinn, “without war or trespass.”  This treaty was absolutely necessary, in order to offer effective resistance to the Danes.  The conduct of the two kings towards each other had not been of