What causes civilian victimization in conventional civil wars and in conventional wars that experience insurgencies? The authors argue that a key driver of civilian victimization is the vulnerability of the incumbent forces, specifically when the conflict’s front line is shifting. Vulnerability is a function of informational and logistical challenges: when the front line is moving, incumbents face increased informational uncertainty and unstable supply chains that augment their vulnerability. Thus, incumbents will increase the use of civilian victimization in response to a scarcity of high-quality information on the location and identity of insurgents, to limit possible information leaks, and to contain supply disruption and logistics support to adversaries. The authors support their argument using matched difference-in-differences analyses of original subnational data on Nazi-Fascist violence in World War II Italy (1943–1945) and qualitative evidence.