Anglo-Irish Treaty, an agreement reached in 1921 between the United Kingdom and the budding Irish Republic that marked the end of the Irish War of Independence and the beginning of the Irish Free State, which was granted the same constitutional status as other countries within the British Commonwealth, with a government system modeled explicitly after that of Canada. The treaty also set the stage for the partition of the 26 counties of southern Ireland from Northern Ireland, made up of six counties that were sometimes called the province of Ulster, which chose to exercise a clause in the treaty that allowed for it to opt out of the Irish Free State. Hotly contested by the different Irish factions, the treaty passed by a slim margin of seven votes in Dáil Éireann, the Irish parliament that had been created in 1919. This ideological split would lead to the Irish Civil War.
The Anglo-Irish Treaty was preceded by the Irish War of Independence, a roughly two-year guerrilla conflict. From 1919 to 1921, Irish republican separatists carried out a series of attacks on British troops, police stations, and other targets on the island. Ireland had attained a semblance of autonomy prior to the conflict when the British government enacted “home rule” in 1914, though that system was never truly implemented because of the outbreak of World War I. In the meantime, many Irish Republicans sought greater freedoms, pushing for a total split from the United Kingdom, which in various forms had controlled nearly all Irish affairs for centuries. Land reform, education, and self-governance were among the separatists’ other major demands. In 1918 the revolutionary party Sinn Féin won 73 out of 105 Irish seats in the general election for the British Parliament, but, rather than take their seats in Westminster, they declared an Irish republic. More than half of the members of the newly elected Dáil were imprisoned by the British when the assembly convened in 1919.
The new Irish Republic, though popular at its outset, did not last long. The Irish Republican Army (IRA) began to run out of ammunition, weapons, and manpower in the summer of 1921. At the same time, back in Britain there was increasing pressure to bring the conflict to a close. No end to the fighting appeared to be in sight, but on July 11, 1921, a truce was reached.
Formal negotiations between the leadership of Sinn Féin and the British began on October 11, 1921, in London. The principal figures on the Irish side were Arthur Griffith, the primary founder of Sinn Féin; Michael Collins, the republic’s minister of finance; Éamonn Duggan; Robert Barton; and George Gavan Duffy. Notably absent from the Irish delegation was the president of the nascent Irish Republic, Éamon de Valera, whose motives for not attending have been debated by historians. The British delegation was made up of Prime Minister David Lloyd George; Austen Chamberlain, the Conservative Party leader; Frederick Edwin, the lord chancellor; Winston Churchill, the chairman of the cabinet commission on Irish affairs; Laming Worthington-Evans, the minister of war; Hamar Greenwood, the chief secretary for Ireland; and Gordon Hewart, the lord chief justice. By December the two sides had agreed to terms.
Among the consequential, far-reaching conditions of the treaty were:
Some of these accords became major points of contention when the treaty returned to Ireland for ratification. In particular, the oath to the British king was something many republicans could not accept. The question of Ulster’s fate was hotly debated. Ultimately, Northern Ireland opted not to join the Free State but to instead remain a part of the United Kingdom with a devolved parliament. This decision led to the partition of the Irish island and years of conflict, particularly in the latter half of the 20th century, as 30 years of sectarian violence wreaked havoc upon Northern Ireland during “The Troubles.”
The Anglo-Irish Treaty was ratified after debate by a slim margin of seven votes in the Dáil. Almost immediately, Ireland descended back into conflict. De Valera resigned as president in protest, adding instant legitimacy to the anti-treaty political position. The IRA also split, with a most of its members opposed to the treaty. A bitter civil war (1922–23) followed that cost more than 1,000 lives, including that of Collins, who was killed in an ambush on August 22, 1922. The war ended in the defeat of the anti-treaty forces.