The outbreak of the Civil War forced pro- and anti-treaty supporters to choose sides. Supporters of the treaty came to be known as "pro-treaty" or Free State Army, legally the National Army, and were often called "Staters" by their opponents. The latter called themselves Republicans and were also known as "anti-treaty" forces, or Irregulars, a term preferred by the Free State side. The Anti-Treaty IRA claimed that it was defending the Irish Republic declared in 1916 during the Easter Rising, confirmed by the First Dáil and invalidly set aside by those who accepted the compromise of the Free State. Éamon de Valera stated that he would serve as an ordinary IRA volunteer and left the leadership of the Anti-Treaty Republicans to Liam Lynch, the IRA Chief of Staff. De Valera, though the Republican 'President as of October 1922, had little control over military operations. Military operations were directed by Liam Lynch until he was killed on 10 April 1923 and then by Frank Aiken, as of 20 April 1923.. How many days after Liam Lynch was killed did Frank Aiken take over?