To cut off time and seal away the past, to proclaim a new beginning in the present and project a better future onto tomorrow - and thus to make history - is a key signature of modern social, political and cultural discourses. In this book, this practice is represented through the metaphor of the Zero Hour, which alludes to the wish to rebuild the past in the face of a crisis-ridden present characterised by growing conceptual insecurity, hoping for a more stable future. Indeed, the ever-new construction of our past, sequenced and ordered in explanatory narratives, bears witness to a future that 'ought to be'. As the case studies in this volume show, this is a global phenomenon. Against the backdrop of a confluence of experiences which unsettled conceptual norms after the First World War, this volume presents a novel approach to global history as it examines ways of breaking with the past and the way in which societies, as well as transnational historical actors, employ key concepts to compose arguments for a better tomorrow.