The most determined resistance to reconquest came from the Gaelic chieftains of Ulster (the northeastern quarter of the island), led by Hugh O'Neill, 2d earl of Tyrone, at the end of Elizabeth's reign. In suppressing their rebellion between 1595 and 1603, English forces devastated the Ulster countryside. Once these chieftains had submitted, however, King James I of England was willing to let them live on their ancestral lands as English-style nobles but not as petty kings within the old Gaelic social system. Dissatisfied with their new roles, the chieftains took ship to the Continent in 1607. This "flight of the earls" gave the English crown a pretext to confiscate their vast lands and sponsor scattered settlements of British Protestants throughout west and central Ulster (the Ulster Plantation). The crown's actions indirectly encouraged the much heavier unsponsored migration of Scots to the coastal counties of Down and Antrim. These settlements account for the existence in present-day Ulster of numerous Protestants--many them Scottish Presbyterians--of all social classes.
Elsewhere in 'modern' Ireland, Protestantism has been confined to a small propertied elite, many of whose members were the beneficiaries of further confiscations a generation after the Ulster Plantation. The pretext for these new confiscations was the rebellion of the Gaelic Irish in Ulster against the British settlers in 1641. Indeed, this rebellion triggered the English Civil War, which put an end to King Charles I's attempt to create an absolutist state (represented in Ireland by the policies of his lord deputy, Thomas Wentworth, 1st earl of Strafford). When the Puritan party defeated Charles, their leader, Oliver Cromwell, quickly imposed (1649-50) English authority on Ireland. Cromwell repaid his soldiers and investors in the war effort with land confiscated largely from the Anglo-Irish Catholics of the Irish midlands who had joined the rebellion hesitantly and only to defend themselves against Puritan policies.