About 95 percent of the Republic's population is Roman Catholic; most of the rest are Protestant.Over 25 percent of Northern Ireland's population is Roman Catholic; about 23 percent is Presbyterian; about 18 percent belong to the Church of Ireland; the rest are members of other churches or of no stated denomination. Patrick came to Ireland and introduced the Gaels to Christianity.The Catholic Emancipation Act followed in 1829 chiefly due to the activities of the Irish politician Daniel O'Connell.During the 1830s and 1840s a new nationalist movement, Young Ireland, arose.After the Anglo-Irish Treaty was signed in 1921, the Irish Free State, whose constitutional status was tied to the British Commonwealth and required allegiance to the Crown, was established.
All of the first three and part of the fourth are situated within the Republic of Ireland.To keep the Irish subservient and powerless the English enacted a series of brutal penal laws, which succeeded so well that eighteenth century Catholic Ireland was economically and socially wasted.In 1800, two years after the defeat of the rebellion of Protestant and Catholic United Irishmen led by Wolfe Tone, the Act of Union was passed, combining Great Britain and Ireland into one United Kingdom.An important legacy of the Viking invasion was the establishment of such cities as Dublin, Cork, Waterford, Limerick, and Wexford.In the second half of the twelfth century King Henry II began the English Lordship of Ireland and the challenge of the Anglo-Norman Conquest commenced.