The history of bacteriophage therapy is traditionally told as a story of booms and busts: following an interwar high, the antimicrobial era triggered a precipitous decline of therapeutic demand in Western countries – despite ongoing popularity East of the Iron Curtain. But how accurate is this account? And what can studying the ongoing circulation of bacteriophages tell us about challenges facing current therapy efforts? In this presentation, I draw on previously unstudied records at Institut Pasteur to map the persistence of large-scale therapy networks in post-war France. Findings highlight the importance of distinguishing between therapeutic markets in North America and Western Europe, reveal the long-term challenges facing phage therapy, and demonstrate the usefulness of engaging with neglected phage-archives in the genomic era.