In the 1801 the London's Parliament vote the Union Act, that suppressed the Parliament of Dublin, fixing the representative shares of Ireland at Westminster. It's the birth of the United Kingdom and the Ireland.
In the 1920 with the Government of Ireland Act, the British set up two different Parliament: Belfast and Dublin.
In the 1921, after two years of clashes between the British government in Ireland and the Irish Republican Army (Ira), the Irish independent war finished, with the respite sealed by the signing of the Anglo-Irish treaty of Peace.
In the 1922-23, the Civil War was fought in 26 Irish countries between supporters and opponents of the Treaty of Peace Anglo-Irish, concluded with the victory of the first one.
1949: On Easter Monday, the Ireland leaves the status of dominion and it became an independent republic.
1921-69: In northern Ireland remains in effect the Government of Ireland Act, that domestic issues were managed by the Belfast's parliament, where prevail always protestant majorities, while from Westminster continue the control of the foreign politics.
1972-1974: At the end of one manifestation for the civil rights in Derry, the paratroopers of the British Army shoot on the mass and the they killed 13 person: this Sunday will be called ‘Bloody Sunday’.
1974/1993: The war continue: the Ira organized a resistance.
1998: On the 10 of April, the Belfast Agreement was signed, known as good Friday. This agreement introduced the North Ireland parliament and it established that the local government respects all the communities.