The 1921 Anglo-Irish Treaty ended the two-year Irish War of Independence and established an independent Ireland, with the six counties of Ulster remaining British. Because the new Irish Free State remained a British dominion, there was tension between anti and pro-Treaty Sinn Féin, with anti-Treaty Sinn Féin wanting full separation from Britain. While Sinn Féin was united in its fight for independence, the tension between anti and pro-Treaty Sinn Féin factions erupted into Civil War, after pro-Treaty Sinn Féin won the 1922 elections by 58:36. Most of the Irish eastern counties had voted overwhelmingly for complete separation, but still won less seats. The only seat not represented by Sinn Féin was Trinity College, Dublin (TCD). The civil war ended in May 1923 with a pro-Treaty victory and in 1926 those opposed to the Treaty became Fianna Fáil, the dominant party of the Republic of Ireland since the 1930s.
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