After the attempted invasion of England by the Spanish Armada in 1588 and subsequent events following that, Queen Elizabeth realised that Ireland was the weakness in her kingdom which could easily be exploited by her enemies in Europe. A fact that was exploited by James Ist during the confrontation with his son-in-law William III in 1690.
At the time the Gaelic lords were openly and secretly organising against her rule in Ireland, a fact emphasised by the following royal proclamation released against Sir Hugh O’Neill who had spent six years in the Royal Courts of London as Baron of Dungannon and was thought of as being loyal to the Queen:-
:“ The Queen made Hugh O’Neill known as ‘The Great O’Neill’ a noble earl. She gave him more than any other earl in Ireland. She gave him allowances every year. Every time he visited London, she gave more land to him and his heirs.
Yet he broke away from her. He has killed her subjects. He has persuaded O’Donnell. Who was loyal, to be part of his rebellion. He has set himself up as Prince of Ulster. He has forced and coaxed the other Ulster chiefs to take part in his rebellion. He has been in touch with her enemy Spain. The Queen is now preparing her armies to capture this great traitor.”
With several failed attempts to pacify the situation with armies, the English changed strategy and built a series of forts around the southern edges of Ulster
, this forced the Gaelic lords to attack which put them in a less favourable position. Eventually this strategy gave the English the upper hand.
Meanwhile O’Neill had gained the support of Spain
who sent troops to support his cause in Ireland bringing the Queen's fears to reality. T
hey landed at Kinsale and prepared to defend it until a Gaelic army under the command of O’Neill and O'Donnell arrived from Ulster
The English under Mountjoy intercepted, engaged and defeated their forces Kinsale in 1601, which forced them to retreat back to Ulster. The Spanish could not hold out against the English at Kinsale and a deal was done which allowed them the retrun with their army to Spain.