This introduction situates liberal ideas of Europe in the interwar period within the context of recent historiographical debates and reassesses their political significance beyond teleological narratives of European integration. It argues that Europe remained a central, albeit contested, frame of reference between the two world wars, particularly in liberal political, economic, and intellectual discourses. Building on longer traditions of liberal internationalism and European thinking that predated 1914, interwar liberal Europe emerged at the intersection of crisis, reform, and political pragmatism. Rather than functioning primarily as a blueprint for supranational integration, liberal Europe often operated as a situational and practice-oriented concept, embedded in concrete political projects and reform agendas. By examining emblematic constellations such as the Locarno treaties, Aristide Briand's proposal for a European federation, and the Paneuropa movement, the introduction highlights the ambivalences inherent in liberal Europeanism, oscillating between normative aspiration and political constraint. The final sections present the contributions to this special issue and argue that, although interwar liberal European projects ultimately failed, they constituted a 'lost Europe' whose ideas, concepts, and actors proved highly transferable after 1945.
