Introduction The Korean War (1950-1953) consisted of two phases. The first was a rapid mobile phase, and the second was a slow and stationary phase. During the stationary phase, approximately 3,000 UN troops became infected with a then unknown agent. The resulting illness began with flu-like symptoms and often progressed to a severe hemorrhagic fever leading to kidney failure and death. However, the cause was not to be identified until well over 20 years following the conclusion of the war when Dr. Ho Wang Lee succeeded in isolating Hantavirus from field rodents. The U.S. Military experience with Hantavirus during the Korean War is a case study of the potential impact of war-related environmental change on disease transmission. The lessons learned from this experience should inform future military medical planning and serve as a reminder of the impact that an unknown agent can have on military operations. Materials and Methods A literature review of all available records with respect to the U.S. Military experience with Hantavirus was conducted. PubMed was the primary search engine used for this review. However, primary literature and historical accounts were also evaluated. All records were examined for environmental, epidemiological, and public health data regarding hemorrhagic fever outbreaks among U.S. forces during the Korean War. The quantitative and qualitative data from these sources were analyzed and evaluated within the context of military medical planning and force health protection to derive lessons learned that should be applied to the management and mitigation of viral disease in future wars. Results Widespread deforestation resulting from war-related efforts most likely played a significant role in the outbreaks of Hantavirus among UN forces during the war. A lack of cultural literacy and an overreliance on erroneous assumptions most likely delayed the identification of the true causative agent. It is conceivable that these delays led to an increased casualty rate and that they had a negative impact on military operations during the war. Conclusions A basic understanding of the ecological mechanisms that maintain species diversity in the local environment coupled with an appreciation for the impact of environmental change on this diversity is of paramount importance for the prevention and mitigation of viral disease outbreaks in the deployed setting. Military medical planners should become familiar with the medical literature of the region in which they will be operating as this literature often describes the agents that will most likely be encountered by U.S. forces.