Historically, the movement of military personnel has had serious consequences on global health. From the decimation of native people in the western hemisphere through the introduction of smallpox to the cholera epidemic in Haiti, militaries and military operations have served to spread disease and facilitate the emergence or re-emergence of novel disease organisms. This chapter provides historical insight into these impacts and reviews the impacts of more recent military activities, especially, recent military operations, on the global burden of disease and health to include vector borne disease, infectious diseases, and emerging diseases across the globe. Emphasis will be placed on current military operations.