De Clare ruled over much of western Ireland from his castle at Bunratty, yet the English respected Thomond as a sovereign state and remained outside its borders.
When news arrived of his allies' defeat at Corcomruadh, Richard de Clare decided to attack the Gaelic stronghold at Dysert O'Dea.
The first division was headed by de Clare's son and marched northwards to Tullach O'Dea in an effort to cut off any help which might arrive from O'Connor of Ennistymon.
O'Dea intentionally made his forces look few in number, for some time fighting in retreat, and when de Clare charged for an attack the Anglo-Normans were ambushed.
[2] The O'Deas were reinforced by the O'Connors and later the O'Briens, who turned the tide of a potentially unpredictable battle[3][4] along with further decisive assistance from the O'Hehir and MacNamaras; and the English were soon defeated.