Robert Childers Barton was one of the most enigmatic figures to emerge from the Irish Revolution, and his place in history was assured when he signed the Anglo-Irish treaty. Although he was a confidante of de Valera, Barton accepted the terms on offer in 1921. He voted for the document in both the Cabinet and the Dáil, recommending the treaty to the House in his Treaty Debate speech. Subsequently, however, he took the anti-treaty side in the Civil War. Although he was central to the birth of the nation, Barton has remained understudied and neglected. This first study of his life focuses on his role during the Irish Revolution, charting his political journey from a Unionist background, through Home Rule and Dual Monarchism, to Republicanism and his later anti-treaty stance. Using multiple sources, including extensive archival material, this book traces the life, times and legacy of a remarkable revolutionary.