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 with the support of at least seven independents. The result was the First Inter-Party Government, with John A. Costello of Fine Gael as its compromise candidate for Taoiseach. Costello was duly nominated, consigning de Valera to opposition for the first time in 16 years. The following year, Costello declared Ireland as a republic, leaving partition as the most pressing political issue of the day. De Valera, now Leader of the Opposition, left the actual parliamentary practice of opposing the government to his deputy, Seán Lemass, and himself embarked on a world campaign to address the issue of partition. He visited