By 1919, Sinn Féin claimed to be Ireland's legitimate government, while the IRA openly challenged the forces of the British Crown. In 1921, the war-weary British began negotiations with Sinn Féin that produced the 1921 Anglo-Irish Treaty, granting dominion status to an Irish Free State that would govern Ireland except for six Ulster counties. Die-hard republicans, however, led by Sinn Féin leader Eamon De Valera, rejected the treaty as a surrender of republican principles and declared themselves Ireland's only legitimate government. In the consequent civil war (1922–1923) the IRA, loyal to De Valera, was defeated but nonetheless refused to surrender.
The IRA's fortunes then began a precipitous decline. De Valera abandoned Sinn Féin in 1926 to form Fianna Fail (Soldiers of Destiny), a political party dedicated to advancing republicanism through conventional political arrangements. In 1932 Fianna Fail formed a government under De Valera, who rewarded republicans who accepted his constitutionalism and punished those who did not. He banned the IRA in 1936, and two years later the moribund Sinn Féin ceded its political authority to the IRA leadership. Responding to IRA actions in 1939, governments in Dublin, Belfast, and London adopted strong security measures that, by 1945, had pushed the IRA to the verge of extinction.
Over the next decade, strong leadership revived the IRA, but the offensive launched in Northern Ireland in 1956, the so-called Border Campaign, ended ignominiously in 1962. Afterward, a coterie of IRA leaders steeped in revolutionary Marxist theory and attracted to political, not military, action took control of the organization and ousted many of those responsible for the Border Campaign.
The outbreak of sectarian violence in Northern Ireland during the summer of 1969 created another breach in Irish republicanism, yet the IRA's leadership chose to continue in their political direction. In response, those favoring the IRA's traditional military approach—the majority of the IRA, as it turned out—formed the Provisional IRA and Provisional Sinn Féin in December 1969. The Provos, as they came to be called, almost immediately came to dominate republicanism; for its part, the official IRA dumped its arms in 1972 and faded into relative obscurity by the decade's end. After the split, the term "IRA" actually referred to the Provos.
The Provisional IRA launched a far-reaching campaign of violence in the hopes of forcing a British withdrawal from Northern Ireland, although a lack of modern weapons and a strong British response hampered this effort. Consequently, the IRA adopted the long-war strategy in the mid-1970s; thereafter, The Troubles, as the conflict in Ireland and Britain was known, settled into a dispiriting pattern of terrorism, failed negotiations, military operations, and reprisals. In the early 1980s, the IRA adopted a bullet-and-ballot strategy, thrusting Sinn Féin into conventional politics in Ireland and Northern Ireland while continuing its military operations. This shift eventually caused another split in the republican movement, with the Continuity IRA and Republican Sinn Féin breaking away in 1986.
By the early 1990s, the IRA–Sinn Féin leadership acknowledged that a military victory was unattainable. Encouraged by Sinn Féin's political successes on both sides of the border, the leadership announced a formal cessation of military operations in 1994. In February 1997, the IRA broke the cease-fire but resumed it after only five months. The 1998 Belfast Agreement guaranteed Sinn Féin a place in Northern Ireland's government and provided for numerous governmental reforms. The IRA, however, refuses to disarm completely, and thus the shadow of the gunman still falls across Irish politics as it has for more than ninety years.
Moloney, Ed. A Secret History of the IRA. New York: Norton, 2002.; O'Brien, Brendan. The Long War: The IRA and Sinn Fein. 2nd ed. Syracuse, NY: Syracuse University Press, 1999.