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
Rúaidhrí de Valera 1947, de Valera became the Archaeological Officer for Ordnance Survey Ireland which permitted him to develop the Survey of the Megalithic Tombs of Ireland project. He went on to write significant papers on Irish prehistory which contributed to his doctorate, awarded in 1954. In 1957, de Valera was appointed Chair of Celtic Archaeology at University College Dublin where he worked to enlarge the department whilst continuing to publish on Irish chamber tombs, especially the Court cairns which he proposed first developed in the west of the country. De Valera later excavated at the Mound of the Hostages at Tara. He