The Introduction establishes the subject of this book, Irish Protestant nationalists, and argues that they constituted an important counterculture in the period. It links the historiography of Protestant nationalists with the competing ‘modernist’ and ‘perennialist’ perspectives on the origins of nationalism, and will argue that Ireland constitutes an important outlier, where both classically modernist and perennialist features co-existed, by reference to Irish history since the Tudor conquest. It argues that although parallels with the central European experience can be discerned, it is difficult to meaningfully place Protestant nationalists within frameworks put forward by scholars of continental Europe. The literature on Protestant nationalists is reviewed, and it is suggested that the way forward for historiography is to follow up the implications of the circles that have been reconstructed by biographers, and produce a collective biography that seeks to reconstruct the entire Protestant nationalist experience. The sources used in this book are discussed, and prosopography, the primary methodology which will be employed, is described and justified. The Introduction closes with a brief statistical summary of the Irish Protestant community in 1901.