What happens when the stressors of combat, fatigue, separation, and personal conflict affect a Soldier's ability to perform their wartime mission? What happens when an upper extremity injury or a significant trauma impacts a Soldier's ability to fire their weapon or complete their mission? The Army has specialized units known as Combat Operational Stress Control (COSC) Detachments and Combat Support Hospitals (CSHs) deployed on the battlefield to address these issues. Occupational therapists (OTs) work in these units and are responsible for facilitating function when Soldiers are faced with these physical and mental injuries. OTs are involved before, during, and after deployment educating, evaluating, and treating units, leadership, commanders, and Soldiers on a myriad of skills, activities, and tasks that enable Soldiers to optimize their overall performance. The history, functional areas, and specific roles of OT in the COSC unit and in the CSH will be discussed in this article. The effectiveness of occupational therapy intervention in these types of units will be discussed in case studies.