Irish Republican Army (IRA), republican paramilitary organization seeking the establishment of a republic, the end of British rule in Northern Ireland, and the reunification of Ireland.

The IRA was created in 1919 as a successor to the Irish Volunteers, a militant nationalist organization founded in 1913. The IRA’s purpose was to use armed force to render British rule in Ireland ineffective and thus to assist in achieving the broader objective of an independent republic, which was pursued at the political level by Sinn Féin, the Irish nationalist party. From its inception, however, the IRA operated independently of political control and in some periods actually took the upper hand in the independence movement. Its membership overlaps with that of Sinn Féin.

During the Anglo-Irish War (Irish War of Independence, 1919–21) the IRA, under the leadership of Michael Collins, employed guerrilla tactics—including ambushes, raids, and sabotage—to force the British government to negotiate. The resulting settlement established two new political entities: the Irish Free State, which comprised 26 counties and was granted dominion status within the British Empire; and Northern Ireland, made up of six counties and sometimes called the province of Ulster, which remained part of the United Kingdom. These terms, however, proved unacceptable to a substantial number of IRA members. The organization consequently split into two factions, one (under Collins’s leadership) supporting the treaty and the other (under Eamon de Valera) opposing it. The former group became the core of the official Irish Free State Army, and the latter group, known as “Irregulars,” began to organize armed resistance against the new independent government.

The ensuing Irish civil war (1922–23) ended with the capitulation of the Irregulars; however, they neither surrendered their arms nor disbanded. While de Valera led a portion of the Irregulars into parliamentary politics with the creation of Fianna Fáil in the Irish Free State, some members remained in the background as a constant reminder to successive governments that the aspiration for a united republican Ireland—achieved by force if necessary—was still alive. Recruiting and illegal drilling by the IRA continued, as did intermittent acts of violence. The organization was declared illegal in 1931 and again in 1936. After a series of IRA bombings in England in 1939, Dáil Éireann (the lower house of the Oireachtas, the Irish parliament) took stringent measures against the IRA, including provision for internment without trial. The IRA’s activities against the British during World War II severely embarrassed the Irish government, which remained neutral. At one point the IRA sought assistance from Adolf Hitler to help remove the British from Ireland. Five IRA leaders were executed, and many more were interned.

After the withdrawal of Ireland from the British Commonwealth in 1949, the IRA turned its attention to agitating for the unification of the predominantly Roman Catholic Irish republic with predominantly Protestant Northern Ireland. Sporadic incidents occurred during the 1950s and early ’60s, but lack of active support by Catholics in Northern Ireland rendered such efforts futile. The situation changed dramatically in the late 1960s, when Catholics in Northern Ireland began a civil rights campaign against discrimination in voting, housing, and employment by the dominant Protestant government and population. Violence by extremists against the demonstrators—unhindered by the mostly Protestant police force (the Royal Ulster Constabulary)—set in motion a series of escalating attacks by both sides. Units of the IRA were organized to defend besieged Catholic communities in the province and were sustained by support from units in Ireland. In 1970 two members of the Fianna Fáil government in Ireland, including future prime minister Charles Haughey, were tried for importing arms for the IRA; they subsequently were acquitted.

Conflict over the widespread use of violence quickly led to another split in the IRA. Following a Sinn Féin conference in Dublin in December 1969, the IRA divided into “Official” and “Provisional” wings. Although both factions were committed to a united socialist Irish republic, the Officials preferred parliamentary tactics and eschewed violence after 1972, whereas the Provisionals, or “Provos,” believed that violence— particularly terrorism—was a necessary part of the struggle to rid Ireland of the British.

Beginning in 1970, the Provos carried out bombings, assassinations, and ambushes in a campaign they called the “Long War.” In 1973 they expanded their attacks to create terror in mainland Britain and eventually even in continental Europe. It was estimated that, between 1969 and 1994, the IRA killed about 1,800 people, including approximately 600 civilians.

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The fortunes of the IRA waxed and waned after 1970. The British policy of interning persons suspected of involvement in the IRA and the killing of 13 Catholic protesters on “Bloody Sunday” (January 30, 1972) strengthened Catholic sympathy for the organization and swelled its ranks. In light of declining support in the late 1970s, the IRA reorganized in 1977 into detached cells to protect against infiltration. Assisted by extensive funding from some Irish Americans, the IRA procured weapons from international arms dealers and foreign countries, including Libya. It was estimated in the late 1990s that the IRA had enough weapons in its arsenal to continue its campaign for at least another decade. The IRA became adept at raising money in Northern Ireland through extortion, racketeering, and other illegal activities, and it policed its own community through punishment beatings and mock trials.

In 1981, after hunger strikes in which 10 republican prisoners died (7 were IRA members), the political aspect of the struggle grew to rival the military one, and Sinn Féin began to play a more prominent role. Sinn Féin leaders Gerry Adams and Martin McGuinness, together with John Hume, head of the Social Democratic and Labour Party (SDLP), sought ways to end the armed struggle and bring republicans into democratic politics. Convinced by the Irish and British governments that a cease-fire would be rewarded with participation in multiparty talks, in August 1994 the IRA declared a “complete cessation of all military activities,” and in October a similar cease-fire was declared by loyalist paramilitary groups fighting to preserve Northern Ireland’s union with Britain. However, Sinn Féin continued to be excluded from the talks because of unionist demands for IRA decommissioning (disarmament) as a condition of Sinn Féin’s participation. The IRA’s cease-fire ended in February 1996, when a bomb in the Docklands area of London killed two people, though it was reinstated in July of the following year. Having agreed that decommissioning would occur as part of the resolution of Northern Ireland’s sectarian conflict, the IRA’s political representatives swore to uphold principles of nonviolence and were included in the multiparty talks beginning in September 1997.

In April 1998 the participants in the talks approved the Good Friday Agreement (Belfast Agreement), which linked a new power-sharing government in Northern Ireland with IRA decommissioning and other steps aimed at normalizing cross-community relations. Significantly, republicans agreed that the province would remain a part of Britain for as long as a majority of the population so desired, thus undermining the logic of continued military action by the IRA. Although the IRA subsequently destroyed some of its weapons, it resisted decommissioning its entire armoury, hampering implementation of key parts of the peace agreement. On July 28, 2005, however, the IRA announced that it had ended its armed campaign and instead would pursue only peaceful means to achieve its objectives. The IRA was back in the headlines in 2015 when an investigation into the murder of a former IRA leader revealed that at least some of the organizational structure of the Provisional IRA was still in place.