Máel Sechnaill mac Máele Ruanaid

[2] Prior to Máel Sechnaill's coming to power, the southern Uí Néill had been disunited, and until Niall Caille defeated Feidlimid mac Crimthainn, king of Munster, at Mag nÓchtair (County Kildare) in 841, the midlands had been repeatedly ravaged by the Munstermen.

[4] Late in 845 the Norse chieftain Thorgest or Turgesius, who had emulated Feidlimid mac Crimthainn by attacking Clonmacnoise and Clonfert, was captured by Máel Sechnaill, and drowned in Lough Owel.

[5] Máel Sechnaill's reign was portrayed in later sources as being frequently a matter of war with the Vikings and Norse-Gaels, thanks largely to works such as the Cogadh Gaedhil re Gallaibh, a panegyric written for Muircheartach Ua Briain, great-grandson of Brian Boru.

[7] The annals record expeditions to Munster to obtain tribute and hostages in 854, 856 and in 858, when his army killed several kings, wasted the land and marched south to the sea.

It is reported that Cerball joined forces with Ivarr, a king of the "Dark foreigners": in 859, they challenged the power of Máel Sechnaill mac Máele Ruanaid.

[11] The Fragmentary Annals quote a lament for Máel Sechnaill:There is much sorrow everywhere;there is a great misfortune among the Irish.Red wine has been spilled down the valley;the only King of Ireland has been slain.

Áed's incessant warfare with the Norse and Norse-Gaels, while militarily successful, produced unexpected consequences in the long term for the position of the northern Uí Néill.

Power and influence in the 10th and 11th centuries rested increasingly with kings who, like Máel Sechnaill, could exploit the wealth of new trading towns and the forces of the Norse and the Norse-Gaels.