Partition represents the most fundamental revolution in modern Irish history. By 1925 the country had been divided into two states embodying rival religious and political identities, an outcome unthinkable only a decade before. While often analysed through the lens of elite high politics, partition was by definition a mass participation event, where decision making was shaped by elections, propaganda and savage acts of violence in defence of or in opposition to the new settlement. By examining the complex interaction of nationalism, religion and politics, Robert Lynch seeks to understand how partition was constructed and imagined by Irish people themselves, arguing for a relocation of partition at the centre of historical understandings of events in Ireland which spanned the Great War. Lynch highlights the deep confusion and expediency which lay behind the partition plan, and how it failed to provide answers to the complex and enduring problems of Irish identity.