Which side did Eamon de Valera support during the Irish Civil War?

During the Irish Civil War (1922–1923), Eamon de Valera supported the anti-treaty side.1

He opposed the Anglo-Irish Treaty of 1921, which established the Irish Free State, primarily because it required members of the Irish parliament to take an oath of allegiance to the British monarch. Following the Dáil's ratification of the treaty, de Valera resigned as president of the republic in protest. He subsequently became the leader of the anti-treaty faction, which engaged in armed resistance against the pro-treaty provisional government led by Michael Collins and Arthur Griffith. By October 1922, de Valera had established a rival republican government, though the anti-treaty forces were ultimately defeated.213