Within days of the election, the short and bitter Civil War erupted between the supporters of the Treaty and its opponents. De Valera and his supporters sided with the anti-treaty IRA against the National Army. The pro-treaty parties, including the Labour Party and Farmers' Party, sat as the Third Dáil. On 6 December 1922, when the new state came into being, pro-treaty Sinn Féin TDs formed the Executive Council of the Irish Free State. Early in 1923, pro-treaty Sinn Féin TDs led by W. T. Cosgrave formed a new party, Cumann na nGaedheal. The Civil War ended in May 1923, when the anti-Treaty IRA stood down and "dumped arms". In the 1923 general election, Cumann na nGaedheal won 41% of the popular vote and 63 seats; the Anti-Treaty faction (standing as "Republican" and led by de Valera) secured 29% of the vote and 44 seats, but applied an abstentionist policy to the new Dáil Éireann.