New scientific advances have created previously unheard of possibilities for enhancing combatants' performance. Future war fighters may be smarter, stronger, and braver than ever before. If these technologies are safe, is there any reason to reject their use? In this article, I argue that the use of enhancements is constrained by the importance of maintaining the moral responsibility of military personnel. This is crucial for two reasons: the military's ethical commitments require military personnel to be morally responsible agents, and moral responsibility is necessary for integrity and the moral emotions of guilt and remorse, both of which are important for moral growth and psychological well-being. Enhancements that undermined combatants' moral responsibility would therefore undermine the military's moral standing and would harm combatants' well-being. A genuine commitment to maintaining the military's ethical standards and the well-being of combatants therefore requires a careful analysis of performance-enhancing technologies before they are implemented.