Partition of Ireland
Beginning on 21 January 1919 with the Soloheadbeg ambush, through the Irish War of Independence, Irish republicans attempted to bring about the secession of Ireland from the United Kingdom of Great Britain and Ireland. Meanwhile, Irish unionistsmost of whom lived in the northeast of the islandwere just as determined to maintain the Union. The British Government, committed to implementing Home Rule, set up a cabinet committee under the chairmanship of southern unionist Walter Long. The Long Committee recommended the establishment of two devolved administrations, dividing the island into two territories: Northern Ireland and Southern Ireland. This was implemented as the Government of Ireland Act 1920. The act entered into force as a "" on 3 May 1921 and provided that Northern Ireland would consist of the six northeastern counties, while the remainder of the island would form Southern Ireland. It was intended that each jurisdiction would be granted home rule but remain within the United Kingdom. The government of Southern Ireland never functioned: the war for independence continued until the two sides agreed a truce in July 1921, ending with the Anglo-Irish Treaty on 6 December 1921.
Ireland–United Kingdom relations
Since at least the 1600s, all of these areas have been connected politically, reaching a height in 1801 with the creation of the United Kingdom of Great Britain and Ireland. About five-sixths of the island of Ireland seceded from the United Kingdom in 1921 as the Irish Free State. Historically, relations between the two states have been influenced heavily by issues arising from their shared (and frequently troubled) history, the independence of the Irish Free State and the governance of Northern Ireland. These include the partition of Ireland and the terms of Ireland's secession, its constitutional relationship with and obligations to the UK after independence, and the outbreak of political violence in Northern Ireland. Additionally, the high level of trade between the two states, their proximate geographic location, their common status as islands in the European Union, common language and close cultural and personal links mean political developments in both states often closely follow each other.