Military metaphors shape the limits and possibilities for conceptualising and responding to complex challenges of contagion. Although they are effective at communicating risk and urgency and at mobilising resources, military metaphors collapse diverse interests and communities into ‘fronts’, obscure alternative responses, and promote human exceptionalism. In this article, I draw from criticisms of the use of military metaphor in scientific and policy descriptions of antimicrobial resistance (AMR) over the past sixty years on order to compare with and explore the use of military metaphors in descriptions of the COVID-19 pandemic. As AMR research has recognised the importance of symbiotic human–microbe relationships and new areas of interdisciplinary collaboration in recent years, a corresponding decline in the use of military metaphor in scientific discourse has begun to emerge. I ask how the legacy of the military metaphor in AMR research can offer lessons regarding or alternatives to the martial language currently saturating responses to the COVID-19 pandemic in the UK.