Abstract: The relationship between lifetime trauma history and posttraumatic stress disorder (PTSD) severity has been established, though the relationship between lifetime trauma history and military-related PTSD symptoms (M-PTSS) has been predominantly studied in reference to childhood trauma alone. The current study was designed to assess the contribution of lifetime trauma history and conflictual military experiences (potentially morally injurious events [PMIEs]) to the experience of M-PTSS and whether the relationship between lifetime trauma history and M-PTSS was mediated by the experience of moral injury during military service. Around 357 Israeli, male, combat veterans completed questionnaires concerning their lifetime trauma history, M-PTSS, and PMIEs as part of a wider study on veteran transition. A regression analysis indicated that higher exposure to PMIEs predicted higher M-PTSS, with betrayal demonstrating the strongest relationship. Furthermore, lifetime traumas predicted M-PTSS, which was partially mediated by betrayal-based PMIEs. Cumulative lifetime trauma history is a potential risk factor for military-related PTSD, in part via an enhanced tendency to appraise betrayal. The current study suggests that adapting commanding doctrines may be beneficial for military-related PTSD prevention and that screening for lifetime trauma exposure may offer an opportunity for targeted support during service. Additionally, viewing betrayal in the military in relation to lifetime trauma history offers an opportunity for integration in therapy.