The Irish Citizen Army , or ICA, was a small group of trained trade union volunteers from the Irish Transport and General Workers' Union (ITGWU) established in Dublin for the defence of worker's demonstrations from the 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 and P. T. Daly. In 1916, it took part in the Easter Rising – an armed insurrection aimed at ending British rule in Ireland.