Irish Citizen Army

The Irish Citizen Army (Irish: Arm Cathartha na hÉireann), or ICA, was a small paramilitary group of trained trade union volunteers from the Irish Transport and General Workers' Union (ITGWU) established in Dublin for the defence of workers' demonstrations from the Dublin Metropolitan Police. It was formed by James Larkin, James Connolly and Jack White on 23 November 1913. Other prominent members included Seán O'Casey, Constance Markievicz, Francis Sheehy-Skeffington, P. T. Daly and Kit Poole. In 1916, it took part in the Easter Rising, an armed insurrection aimed at ending British rule in Ireland.

Following the Easter Rising, the death of James Connolly and the departure of Jim Larkin, the ICA largely sidelined itself during the Irish War of Independence by choosing to only offer material support to the Irish Republican Army and not become directly involved itself. Following the ICA's declaration in July 1919 that members could not be simultaneously members of both the ICA and the IRA, combined with the ICA's military inactivity, there was a steady stream of desertion from the ICA. During the Irish Civil War, the ICA declared itself "neutral", resulting in further departures from the organisation.

The ICA ceased to hold any military importance from 1920 until 1934 when the newly formed Republican Congress attempted to revive it. However, when the Republican Congress split and collapsed over ideological in-fighting, so too did the ICA.