Anglo–Irish relations

War, diplomacy, and accord have marked relations between the UK and Ireland in the 20th century. In 1900 the island of Ireland was governed by the British government at Westminster as an integral part of the UK. By the end of the century only Northern Ireland (6 of Ireland's traditional 32 counties) remained in the UK, the majority of Ireland having been granted independence as the Irish Free State under the 1921 Anglo-Irish Treaty (Treaty of London). The UK government's Ireland Act of 1949 formally recognized the secession of the Republic of Ireland from dominion status, and confirmed citizens of the Republic in the rights that they had hitherto enjoyed in the UK.

Home rule In 1912 the UK agreed to accept Irish home rule. However, this was opposed by the Protestants in Ulster, who set up the Ulster Volunteer Force (UVF) to oppose home rule by force if necessary. The Catholic Irish nationalists set up the Irish Volunteers to defend the principle of home rule. Civil war was avoided only because of the start of World War I in 1914, and the question of Irish home rule was postponed. In 1916 a group of Irish republicans staged the Easter Rising, an unsuccessful attempt to overthrow British rule in Ireland.

The 1918 general election saw the nationalist Irish Parliamentary Party, led by John Redmond, lose almost all its seats, and the Republican Sinn Fein emerge as the dominant political force in Ireland. Sinn Fein were not prepared to accept home rule – they wanted total independence. The Sinn Fein members of Parliament refused to take their seats in Westminster, set up an Irish parliament (Dáil Éireann) in Dublin, and ignored British rule in Ireland. The subsequent Anglo-Irish War, or War of Independence (1919–21), led to the Anglo-Irish Treaty, and independence for the southern 26 counties of Ireland as the Irish Free State within the British Commonwealth. The northern six counties remained part of the UK, as Northern Ireland.

Irish Free State The Dáil Éireann narrowly ratified the Anglo-Irish Treaty, as many republicans refused to accept the partition of Ireland and the necessity to take an oath of allegiance to George V as Irish head of state. Relations between the Irish Free State and the UK were not close. After the victory of Éamon de Valera's Fianna Fáil party in the 1932 Irish elections, the Irish government refused to pay land annuities due to Britain, an annual sum of £3 million. A trade tariff war erupted between the two countries after Britain tried to recoup its losses through the imposition of duties, until an agreement in 1938 commuted the Land Annuities to a single payment of £10 million; the British government also relinquished its rights to certain Irish ports.

Irish Constitution 1937 In 1937 Irish leader Éamon de Valera introduced an Irish Constitution that further diminished ties between Britain and the Irish Free State, declaring Ireland a sovereign state as Eire. During World War II Ireland remained neutral, causing great resentment in Britain as the Irish were considered to be supporting Hitler's Germany by refusing to fight, although a large number of men and women from Eire joined the British forces or carried out other war work in the UK. Furthermore, the Irish Republican Army (IRA) continued its fight for an independent, unified Ireland through terrorist activities, mainly in Northern Ireland, but also on the British mainland and, to a lesser extent, in Eire.

Republic of Ireland At the end of World War II, Ireland moved towards full independence from Britain, and in 1949 the Republic of Ireland was officially recognized by Britain. Irish people were still able to settle and work in Britain as they had been before 1949. Therefore, by 1950 Ireland was completely separated into an independent republic in the south while the UK retained ownership and control over Northern Ireland.

Northern Ireland Until violence erupted in Northern Ireland in the late 1960s, relations between Ireland and Britain were generally good, with cooperation between Northern Ireland and the Republic of Ireland. However, after 1969 relations deteriorated, as the Republic was accused of supporting and protecting IRA terrorists. In 1971 the Irish government took Britain to the European Court of Human Rights over internment in Northern Ireland. Relations improved with the 1973 Sunningdale Agreement between the Republic of Ireland and the UK, and in 1985 Britain and Ireland signed the Anglo-Irish Agreement, setting up increased cooperation and contact between Britain and Ireland over political, legal, security, and cross-border matters. It was also agreed that the status of Northern Ireland would not be changed without the consent of a majority of the people. However, the clause in the 1937 Irish Constitution claiming ownership of Northern Ireland and the refusal of the Irish government to extradite IRA terrorists to Britain for trial continued to cause disagreement.

The 1990s saw a great increase in joint efforts to encourage the Northern Ireland peace process. In 1993 Britain and Ireland issued the Downing Street Declaration in an attempt to start talks on the future of Northern Ireland and the two governments worked together to convince the various parties in Northern Ireland to end the violence of ‘the Troubles’. In 1998 the Good Friday agreement (Belfast Agreement) set out a programme for the devolution of a wide range of legislative powers to a Northern Ireland Assembly. Although this came into force in 1999, and the Republic of Ireland formally withdrew its claim to Northern Ireland, stalemate over the decommissioning of the IRA continued to cause problems, and caused devolution to be suspended in 2000, and again in 2001.