Introduction and Aims Effective, structured handovers of care are crucial for patient safety, ensuring accurate reporting of critical information from one provider to another. Communication errors during handovers contribute to 80% of medical errors. At the Uniformed Services University of the Health Sciences (USUHS), medical and advanced practice nursing students were taught handovers in an operational environment through brief lectures and field demonstrations using the MIST mnemonic (Mechanism of Injury, Injuries sustained, Signs & Symptoms, and Treatments rendered). It was unknown whether this usual training produced effective handover quality. This study aimed to identify gaps in our usual handover training and evaluate a new standardized curriculum we called ECCCHO (Effective Combat Casualty Care Handover Operations). Methods This was an observational controlled study of USUHS medical students and advanced practice nursing students across three combat field exercises over different class years. The control group included students from the 2023-2024 classes who were taught patient handovers through brief classroom lectures and field demonstrations. The intervention group included students from the 2025-2027 classes trained under the ECCCHO curriculum. This curriculum was based on a review of quality elements in a patient handover and guidelines published for Tactical Combat Casualty Care (TCCC). Key points included verbally stating MIST elements, asking for readback, stating a definitive handover statement such as “the patient is yours” and then handing over the DD-1380 card. Our intervention consisted of a 15-minute narrated PowerPoint lecture, a video demonstration of a quality MIST handover, and three table-top simulations of a handover with peer observations and feedback. We observed and recorded patient handovers in our field exercises for control and intervention groups during simulated combat conditions. Our outcome variables were the percentage of students who: 1. Verbalized each of the MIST elements, 2. Asked for a readback, 3. Verbalized a definitive handover statement and 4. Transferred the DD-1380 card. All observations were coded and differences analyzed using chi-square tests. Results We recorded 227 handover observations in the control group and 426 in the intervention group. Compared with controls, the intervention group achieved higher completion of nearly all handover elements: Mechanism of Injury increased from 66.5% to 81.9% (p<0.001), Signs and Symptoms from 66.5% to 84.0% (p<0.001), and Treatments Rendered from 89.4% to 99.8% (p<0.001). Injuries Sustained rose from 87.7% to 91.8% but was not significant (p>0.05). Handover Skills improved markedly, requests for readback from 12.6% to 70.8%, definitive handover statements from 2.6% to 80.5%, and DD-1380 card transfer from 45.4% to 84.0% (all p<0.001). Conclusions Our ECCCHO curriculum standardized the handover process and significantly improved communication performance among military medical trainees in simulated combat environments. A brief, structured approach incorporating a MIST handover demonstration and table-top simulation effectively improved patient care handovers compared to our usual approach. Future research will compare groups within the same class over time to look for longevity of training across all field exercises.