In 1919 Childers was made Director of Publicity for the First Irish Parliament. In 1920 Childers published "Military Rule in Ireland", a strong attack on British policy. At the 1921 elections, he was elected (unopposed) to the Second Dáil as Sinn Féin member for the Kildare–Wicklow constituency, and published the pamphlet "Is Ireland a Danger to England?", which attacked British prime minister David Lloyd George. He became editor of the "Irish Bulletin" after the arrest of the young Desmond FitzGerald. He stood as an anti-Treaty Sinn Féin candidate at the 1922 general election but lost his seat.