Éamon de Valera new line. However, a vote to accept the Free State Constitution (contingent on the abolition of the Oath of Allegiance) narrowly failed. Soon afterward, de Valera resigned from Sinn Féin and seriously considered leaving politics. However, one of his colleagues, Seán Lemass, convinced de Valera to found a new republican party. In March 1926, with Lemass, Constance Markievicz and others, de Valera formed a new party, Fianna Fáil ("The Warriors of Destiny"), a party that was to dominate 20th-century Irish politics. While Sinn Féin still held to an abstentionist line, Fianna Fáil was dedicated to republicanising the Free State from
Éamon de Valera the work of Michael Collins and based on three sources: British oaths in the dominions, the oath of the Irish Republican Brotherhood and a draft oath prepared by de Valera in his proposed Treaty alternative, "Document No. 2"). De Valera began a legal case to challenge the requirement that members of his party take the Oath, but the assassination of the Vice-President of the Executive Council (deputy prime minister) Kevin O'Higgins on 10 July 1927 led the Executive Council under W. T. Cosgrave to introduce a Bill on 20 July requiring all Dáil candidates to promise on oath that if