Under the banner of martial empiricism, we advance a distinctive set of theoretical and methodological commitments for the study of war. Previous efforts to wrestle with this most recalcitrant of phenomena have sought to ground research upon primary definitions or foundational ontologies of war. By contrast, we propose to embrace war’s incessant becoming, making its creativity, mutability and polyvalence central to our enquiry. Leaving behind the interminable quest for its essence, we embrace war as mystery. We draw on a tradition of radical empiricism to devise a conceptual and contextual mode of enquiry that can follow the processes and operations of war wherever they lead us. Moving beyond the instrumental appropriations of strategic thought and the normative strictures typical of critical approaches, martial empiricism calls for an unbounded investigation into the emergent and generative character of war. Framing the accompanying special issue, we outline three domains around which to orient future research: mobilization, design and encounter. Martial empiricism is no idle exercise in philosophical speculation. It holds the promise of a research agenda apposite to the task of fully contending with the momentous possibilities and dangers of war in our time.