The 2022 Russian invasion of Ukraine demonstrates once again the vulnerability and significance of cities in war. In this article, and with inspiration from Ian Hacking’s historical ontology, I draw on a varied source material to argue that there is today something new and qualitatively distinct in how the U.S. military approaches war and combat in urban environments. By investigating the historical-conceptual trajectory of “the urban” in U.S. military practice from the mid-eighteenth century until today, the article argues that a gradual shift has occurred in terms of how the armed forces have begun to think of and act on the urban as a distinct object that can be made “known” and managed in and through a specialized knowledge. A “military urban” has come into being, conditioned by a particular epistemic and implying a new way for urban spaces to exist in war. The article’s findings have implications for our understanding of what the urban is for militaries and, relatedly, for grasping the role of epistemics and knowledge practices in conditioning military actions in and on urban spaces.