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 Sinn Féin. In March 1926, de Valera, along with most anti-Treaty politicians, founded a new party called Fianna Fáil and ended their boycott of the institutions of the Free State.