The Irish Citizen Army (ICA) is formed on November 23, 1913, at the height of the Dublin Lockout. Its purpose is to enable the locked-out men to defend themselves in clashes with the Dublin Metropolitan Police and to counteract the demoralizing effects of unemployment by providing discipline, cohesion and purpose. The idea of forming a force apparently is first formally proposed in 1913 by Captain James Robert “Jack” White, an ex-army officer from County Antrim, who had been educated at Winchester College and Royal Military College, Sandhurst. During a speech in August, James Larkin had already suggested that the workers form a force. He publicly repeats this instruction on November 13. James Connolly likewise urges the men to train “as they are doing in Ulster.” Two weeks later drilling begins. According to the ICA constitution, its members are to “work for an Irish republic and for the emancipation of labour.” Larkin is anxious that those who enlist should not only espouse these principles but also be members of unions recognised by the Irish Trades Union Congress.
Despite competition from the Irish Volunteers, which launches on November 25, 1913, ICA membership quickly surpasses 1,000. However, after the dispute is over in January 1914 and the men return to work, the “army” all but disappears. But it is Connolly above all who, after his appointment as its commandant and as leader of the Irish Transport and General Workers Union, rescues it from terminal decline and welds it into a potent force and potential weapon for his own use. He determines its structure, vets its officers and imposes a rigid discipline. He also demands an ideological commitment to revolution and the goal of an independent Irish socialist republic. The force’s guiding principle is that “the ownership of Ireland, moral and material, is vested by right in the people of Ireland.” Its membership remains small but it is otherwise superior to the much larger Irish Volunteers in its unity of purpose, lack of factional and ideological division and in the quality of its training.
After the outbreak of World War I, Connolly has become increasingly committed to fomenting an insurrection in Ireland. This is reflected in his military preparations with the ICA. He uses its headquarters, Liberty Hall, as his base. Fearing he might act on his own, and recognising the merits of collaboration, the Irish Republican Brotherhood Military Council informs him of their own clandestine plans for a rising and an agreement is reached.
During Easter week of 1916, 219 ICA men fight alongside over 1,300 from the Irish Volunteers. As the appointed leader of both forces in Dublin, Connolly skillfully ensures that the ideological and social divisions and personality clashes, which have hitherto blighted their relationship, are largely overcome. ICA forces are mainly concentrated at the General Post Office (GPO), the College of Surgeons and Dublin’s City Hall. They win volunteer admiration for their professionalism, dedication, and ruthlessness. Two of their leaders are subsequently executed – Connolly and Michael Mallin, the ICA Chief of Staff. Constance Markievicz, Mallin`s second-in command, is reprieved. Others are imprisoned or interned. The ICA is not revived after the insurrection. The new leadership of the ITGWU focuses instead on building up the union, safeguarding members’ wages and improving working conditions.