Irish Republican Army (1917–22)

Irish Republican Army (Óglaigh na hÉireann)
Participant in the Irish War of Independence
The Seán Hogan flying column during the War of Independence
Active	1919–1922
Leaders	IRA National Executive
Headquarters	Dublin
Area of operations	Ireland
Strength	c. 100,000 enrolled by 1918, c. 15,000 effectives (maximum strength including front-line and support personnel) of whom 3,000 served as fighters at any one time
Originated as	Irish Volunteers
Became	Split into Pro-Treaty Irish Republican Army and Anti-Treaty Irish Republican Army
Opponents	United Kingdom

The Irish Republican Army (IRA) (Irish: Óglaigh na hÉireann) was an Irish republican revolutionary paramilitary organisation. The ancestor to many groups also known as the Irish Republican Army, it was descended from the Irish Volunteers, an organisation established on 25 November 1913 that staged the Easter Rising in April 1916. In 1919, the Irish Republic that had been proclaimed during the Easter Rising was formally established by an elected assembly (Dáil Éireann), and the Irish Volunteers were recognised by Dáil Éireann as its legitimate army. Thereafter, the IRA waged a guerrilla campaign against the British occupation of Ireland in the 1919–21 Irish War of Independence.

Following the signing in 1921 of the Anglo-Irish Treaty, which ended the War of Independence, a split occurred within the IRA. Members who supported the treaty formed the nucleus of the Irish National Army. However, the majority of the IRA was opposed to the treaty. The anti-treaty IRA fought a civil war against the Free State Army in 1922–23, with the intention of creating a fully independent all-Ireland republic. Having lost the civil war, this group remained in existence, with the intention of overthrowing the governments of both the Irish Free State and Northern Ireland and achieving the Irish Republic proclaimed in 1916.

The Irish Volunteers, founded in 1913, staged the Easter Rising, which aimed at ending British rule in Ireland, in 1916. Following the suppression of the Rising, thousands of Volunteers were imprisoned or interned, leading to the break-up of the organisation. It was reorganised in 1917 following the release of first the internees and then the prisoners. At the army convention held in Dublin in October 1917, Éamon de Valera was elected president, Michael Collins Director for Organisation and Cathal Brugha Chairman of the Resident Executive, which in effect made him Chief of Staff.