This study examined the role of cumulative combat experiences with regard to military performance and conduct and mental health among a sample of young soldiers from the Army STARRS dataset (N = 5,283). Higher levels of cumulative combat experiences were directly related to poorer performance and conduct and a greater likelihood of anxiety, depression, and post-traumatic stress disorder (PTSD). Military performance and conduct served as a linking mechanism between combat experiences and mental health. Using moderated mediation structural equation modeling, relationship disruptions were found to exacerbate the adverse effects of combat experiences; conversely, unit cohesion buffered the impact of combat experiences. Implications for military helping professionals include identifying leverage points for intervention, particularly strengthening the social connections of service members within and outside the military.