The history of Ireland from 1691–1800 was marked by the dominance of the Protestant Ascendancy. These were Anglo-Irish families of the Anglican Church of Ireland, whose English ancestors had settled Ireland in the wake of its conquest by England and colonisation in the Plantations of Ireland, and had taken control of most of the land. Many were absentee landlords based in England, but others lived full-time in Ireland and increasingly identified as Irish.. During this time, Ireland was nominally an autonomous Kingdom with its own Parliament; in actuality it was a client state controlled by the King of Great Britain and supervised by his cabinet in London. The great majority of its population, Roman Catholics, were excluded from power and land ownership under the penal laws. The second-largest group, the Presbyterians in Ulster, owned land and businesses but could not vote and had no political power. The period begins with the defeat of the Catholic Jacobites in the Williamite War in Ireland in 1691 and ends with the Acts of Union 1800, which formally annexed Ireland in a United Kingdom from 1 January 1801 and dissolved the Irish Parliament.

Ireland during the period of 1536–1691 saw the first full conquest of the island by England and its colonisation with mostly Protestant settlers from Great Britain. This would eventually establish two central themes in future Irish history: subordination of the country to London-based governments and sectarian animosity between Catholics and Protestants. The period saw Irish society outside of the Pale transform from a locally driven, intertribal, clan-based Gaelic structure to a centralised, monarchical, state-governed society, similar to those found elsewhere in Europe. The period is bounded by the dates 1536, when King Henry VIII deposed the FitzGerald dynasty as Lords Deputies of Ireland, and 1691, when the Catholic Jacobites surrendered at Limerick, thus confirming Protestant dominance in Ireland. This is sometimes called the early modern period.