Irish Republic the Third Dáil, and all future institutions arising from it, as illegal. (See Second Dáil). The anti-Treaty side was then defeated in the Civil War. Most militant opposition to the Free State came to an end on 24 May 1923 when Frank Aiken, chief-of-staff of the IRA issued the order to "dump arms" and Éamon de Valera issued his address to the "Legion of the Rearguard". Éamon de Valera continued as president of the Sinn Féin political party. In March 1926, Éamon de Valera, along with most anti-Treaty politicians, founded a new party called 'Fianna Fáil' and ended their boycott
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