Since 1295, a parliament of English barons and prelates began to gather in Eastern Ireland. Great influence was acquired by English feudal lords, who, despite the ban, intermarried with the heads of Irish clans and inherited their lands. In the 15th century, representatives of the Anglo-Irish Geraldine family – Desmonds and Kildares – almost monopolistically used the post of governor of the island. With the accession of the Tudors in 1485 and the establishment of absolutism in England, the English government began to strengthen its power in the country.
During the entire period of the 12th-15th centuries, the Irish clans waged a liberation struggle against the English conquerors (uprisings of 1315-1318, 1394, 1399, etc.).
The spread of the English Reformation to Ireland in 1536-1537 gave rise to the confiscation of the lands of the leaders and ordinary members of the Irish clans under the pretext of their deviation from the "true" faith. Ireland became the object of colonial plunder both for the ruined English feudal nobility, and for the "new nobility" and the bourgeoisie – classes that arose in the process of initial accumulation, which prepared the establishment of the bourgeois system in England.
The response of the Irish people to the policy of expropriation was to strengthen the liberation struggle. Only during the reign of Elizabeth (1558-1603) there were 4 major uprisings on the island: in 1565-1567 in Ulster (Northern Ireland), in 1570-1573 and 1579-1583 in Munster (Southern Ireland), in 1595-1603 in Ulster and Munster. Against the Irish rebels, the British used the most brutal methods of colonial wars.
The period of the English bourgeois revolution of the 17th century played a decisive role in the colonial enslavement of the island. The colonization policy of England caused a powerful uprising of the Irish masses, which broke out in 1641. In August 1649, the leader of the English bourgeoisie and the "new nobility" O. Cromwell landed in Ireland with an army, who caused a massacre of the Irish garrisons and the population in Drogheda and Wexford. The uprising was finally suppressed in 1652. The Irish people were subjected to severe repression. The "Acts on the Establishment of Ireland" of August 12, 1652 and September 26, 1653 authorized the mass seizure of land by English officers, creditors of parliament, speculators, the conquest of Ireland, the transformation of the island into a citadel of landlords Cromwell prepared the ground for the restoration of the Stuarts (in 1660). Issued in 1662 by the government of Charles II, the new "Act on the Establishment of Ireland" secured the colonizers the lands they had seized. In 1688-1691, a new uprising took place in Ireland, brutally suppressed by the colonizers.