Irish Republic the Third Dáil, and all future institutions arising from it, as illegal. (See Second Dáil). The anti-Treaty side was then defeated in the Civil War. Most militant opposition to the Free State came to an end on 24 May 1923 when Frank Aiken, chief-of-staff of the IRA issued the order to "dump arms" and Éamon de Valera issued his address to the "Legion of the Rearguard". Éamon de Valera continued as president of the Sinn Féin political party. In March 1926, Éamon de Valera, along with most anti-Treaty politicians, founded a new party called 'Fianna Fáil' and ended their boycott
Éamon de Valera Dáil and the electorate, and the anti-Treatyites under the nominal leadership of de Valera, now descended into the Irish Civil War (June 1922 to May 1923), in which the pro-treaty Free State forces defeated the anti-Treaty IRA. Both sides had wanted to avoid civil war, but fighting broke out over the takeover of the Four Courts in Dublin by anti-Treaty members of the IRA. These men were not loyal to de Valera and initially were not even supported by the executive of the anti-Treaty IRA. However, Michael Collins was forced to act against them when Winston Churchill threatened to re-occupy