World War I pushed the boundaries of modern medicine. Doctors, nurses, and others struggled to keep up with the devastating impact of this first, truly modern war. There were over 40 million casualties (both civilian and military) and 20 million deaths as a direct result of the war. The United States had over 320,000 casualties with over 10,000 from Missouri. Disease, particularly the 1918 flu epidemic, caused over a third of all deaths. This presentation will explore how medicine and medical practitioners responded to battlefield injuries and disease during the war.