The centenary of the signing of the Anglo-Irish Treaty recalls not only the emergence of an independent Irish nation but also a new phase in the turbulent relationship between Ireland and Britain. The Treaty was a compromise by no means acceptable to all, as the new Irish Free State would remain under the Crown. The British government’s insistence on this requirement looks, from a historical perspective, obstinate and unnecessary. The bloody civil war which followed, between the two Irish sides, for and against the treaty, set brothers and sisters against brothers and sisters. The resentments were slow to fade and hard to forgive, and British responsibility for causing them has never been properly admitted.