Gaelic Ulster's Culloden
With the death of Shane O'Neill in 1598 at the hands of the MacDonnells a Gaelic star came on the scene in the form of Hugh O'Neill. This son of the murdered Matthew, son of Con O'Neill. Hugh O'Neill. Brought up in England, this Hugh had been returned to Ulster under the English title of Earl of Tyrone. In Hugh O'Neill, Gaelic Ulster was to find a warrior in the Calibre of Brian Boru. Hugh O'Neill took the unpresidented steps of forming alliances with former enemies of the O'Neills, especially with the McDonnells of Donegal and Maguires of Fermanagh. The role of the O'Cahans in the rise and fall of Hugh O'Neill, would lead them to battlefields on the borders of Ulster and to the bottom tip of Ireland to the battlefield at Kinsale.
Kinsale was Gaelic Ulster's Culloden; all of O'Neills and his allies' previous triumphs were now wiped out at a stroke and, though the war continued for more than another year. For Donnell O'Cahan the war was intensified by the scotched earth policy of the English commander Dowcra, on the borders of O'Cahan territory with the construction of three forts, at Dunnalong, Culmore and Derry. Donnell O'Cahan made preparations for heavy raiding by the English. He came to an arrangement with the MacDonnells of Antrim as to the safety of their cattle. The English had raided each Clan and when O'Cahan suffered from attack, he would drive his cattle into the Route, while in the case of the MacDonnells if attacked from the English fort at Carrickfergus, the scots were to drive their cattle into O'Cahan's lands near the Bann river. The English Dowcra determined to counter this plan with the planting of a garrison at Coleraine. This would divide the MacDonnells from the O'Cahans, and facilitate the destruction of crops and livestock in O'Cahans country. The overriding factors that caused the defeat of Gaelic Ulster and the O'Cahans war efforts, were their inferiority in arms and lack of artillery, the scotched earth policy pursued, and the policy of divide and conquer which led to important assistance being given to the English by the Irish of Innishowen namely Niall Garbh O'Donnell, Cahir O'Doherty and Shane Cossagh O'Cahan brother of the O'Cahan Chief. Within the O'Cahan Clan itself there were found among the clansmen those who were willing to act as spies and guides to the English troops. Dowcra's letter of 11th March 1602, to the English government, shows how much the English depended on the efficiency of there spy system. The English had spies in Tyrone to find out if O'Neill was sending O'Cahan reinforcements, and actually had spies within O'Cahan's camp itself who noted what outside forces arrived and what the total strength of O'Cahan's forces was. On the report of these spies, Docwra decided the tactics to be pursued.