Leader of Sinn Féin joined opposing sides with De Valera leading the Anti-Treaty faction, while Griffith joined the Pro-Treaty faction, which later became Cumann na nGaedheal. De Valera’ successor John J. O'Kelly was one of four leaders who served for brief periods of time as Sinn Féin’s party membership declined in favour of Fianna Fáil and Fine Gael. In 1937, Margaret Buckley became the first female President of Sinn Féin. During her thirteen years as leader, she vastly improved the relations between the IRA and the party. She was succeeded by Paddy McLogan and Tomás Ó Dubhghaill who both helped rebuild party support in
Sinn Féin Sinn Féin Sinn Féin ( ; ; is a left-wing Irish republican political party active in both the Republic of Ireland and Northern Ireland. The original Sinn Féin organisation was founded in 1905 by Arthur Griffith. It took its current form in 1970 after a split within the party (with the other side becoming the Workers' Party of Ireland) and has historically been associated with the Provisional Irish Republican Army (IRA). Mary Lou McDonald has been party president since February 2018. Sinn Féin is the largest nationalist party in the Northern Ireland Assembly, and the joint-largest overall (alongside the Democratic