The Irish Citizen Army (ICA) was a paramilitary group of trained trade union volunteers from the Irish Transport and General Workers' Union (ITGWU), founded on this day in 1913. The ICA was founded by James Larkin, James Connolly, and Jack White in Dublin, Ireland, and established for the defense of workers' demonstrations from the Dublin Metropolitan Police.

The ICA was first formed in the turmoil of the Lockout of 1913. The violence at union rallies during the strike prompted Larkin to call for a workers' militia to be formed. During the lockout, they armed with hurleys and bats to protect workers' demonstrations from the police.

In 1916, it took part in the Easter Rising, an armed insurrection aimed at ending British rule in Ireland. Despite the relatively small size of the army, it was more organized than the larger Irish Volunteers, with its members receiving superior training and being less affected by factional and ideological division.

The ICA became involved in the War of Independence, taking responsibility for parts of Dublin and aiding the Irish Republican Army (IRA) in various operations.