The Anglo-Irish Treaty of December 1921 is one of the most important documents in modern Irish history. How was it negotiated? Who signed it? What was life like for the Irish delegation that went to London to conclude it? Using the documentary record that they left behind, much of it published here for the first time, this book explores the world that the Irish delegation lived in for seven fateful weeks in 1921, and how the Treaty that they negotiated came into being. This catalogue is based on an exhibition by the National Archives to mark the centenary of the signing of the Treaty, as part of the National Archives Commemorations Programme 2021-2 marking the National Archives' role as the official repository of the records of the state. They are presented in partnership with the Royal Irish Academy, the National Library of Ireland and the Office of Public Works, with records included from the collections of the Military Archives, Dublin and University College Dublin Archives.