How do military losses impact political behavior? This paper examines the effects of reports about local soldiers killed in action (KIA) during the ongoing war in Ukraine on online political behavior reflecting patriotic sentiment or regime support in soldiers' hometowns. Using more than 20 million posts from 36,000 geo-referenced social media groups, we employ topic-specific engagement metrics as proxies for authorities' approval and patriotism. Leveraging variation in the timing of KIA reports across Russian municipalities and a staggered treatment rollout design, we show that war fatalities lead to a sustained decline in social media engagement with content referencing authorities, with the magnitude of this effect increasing over the course of the war. At the same time, interaction with patriotic and military topics temporarily increases, primarily driven by engagement with posts referencing the war in Ukraine and fallen soldiers. In addition, these effects are amplified in municipalities where local online group administrators publish soldiers' obituaries, highlighting the importance of direct access to information for the effect to develop fully. Sentiment analysis further reveals that engagement with propagandistic content – emotionally appealing and politically relevant – drops after KIA reports for both patriotic and regime-related topics, suggesting that exposure to war fatalities erodes trust in state-promoted narratives. These findings highlight the critical role of personal exposure to war casualties and access to such information in shaping public discourse, with implications for understanding political attitudes in conflict settings.