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 nominally head of the anti-Treatyites, de Valera had little influence. He does not seem to have been involved in any fighting and had little or no influence with the military republican leadership - headed by IRA Chief of Staff, Liam Lynch. De Valera and the anti-Treaty TDs formed a "republican government" on 25 October 1922 from anti-Treaty TDs to "be temporarily the Supreme Executive of the Republic and the State, until such time as the elected Parliament of the Republic can freely assemble, or the people being rid of external aggression are at liberty to decide freely how they are