 During its first decade , the newly formed Irish Free State was governed by the victors of the civil war . When de Valera achieved power , he took advantage of the <unk> of Westminster and political circumstances to build upon <unk> to greater sovereignty made by the previous government . The oath was abolished and in 1937 a new constitution was adopted . This completed a process of gradual separation from the British Empire that governments had pursued since independence . However , it was not until 1949 that the state was declared , officially , to be the Republic of Ireland . 
