Civil war
For most of the 16th century England consolidated its rule in Ireland amid a series of bloody conflicts. Peace came in 1603, at least for a period, while English and Scottish Protestants continued to settle in certain counties of Ireland.
War in Ireland began again in 1641, when Irish Catholics rebelled against English Protestant rule. When news of the insurrection reached King Charles I, he and the English Parliament promised to send troops.
Cost
More than 1,000 soldiers reached Dublin by the end of that year, but Parliament resolved that the cost of the army should fall on Ireland rather than the English Exchequer.
Almost every Irish rebellion in the past had been followed by confiscation of land and estates by the English Crown. In March 1642 Charles gave his assent to an Act that promised payment in Irish property to those who had advanced money for the war.
When the Irish insurrection became embroiled with the War of the Three Kingdoms - England, Scotland and Ireland - and, most significantly, the English Civil Wars, much of the money intended for the Irish war ended up funding the English Parliament's fight against the Royalists.
Cromwell
After more than a decade of conflict Oliver Cromwell, one of the commanders of the New Model Army which defeated the Royalists, brutally re-conquered Ireland from 1649-53 on behalf of the English Commonwealth following the execution of Charles I.
All Ireland, wrote the historian J C Beckett, now “lay helpless in the hands of the English parliament”.