Epidemics and the American Military
Five Times Disease Changed the Course of War
Jack McCallum, Naval Institute Press, 2023, 288 pages
Book Review published on: August 22, 2025
The Frontier Army Museum sits at Fort Leavenworth located adjacent to the schoolhouses of the U.S. Army's premier educational program for field grade officers. In the museum, there is a display case of military medical exhibits, a quiet reminder for the next generation of America's military leaders, that disease and pathogens are as great a threat as any human adversary. Just over one hundred miles away, the 1918 Spanish flu that killed fifty million people worldwide—twice the battlefield casualties of World War I—likely originated at Camp Funston, Kansas.
Militaries throughout history have been at the front lines of disease. The nickname "limeys" originated with the British Navy's campaign to stock citrus fruits to ward off scurvy. The work by Walter Reed and William Gorgas on yellow fever prompted the mosquito eradication program in Panama that enabled construction of the Canal. One of the Frontier Army Museum's exhibits describes the military origins of the EpiPen as a method to counteract exposure to nerve agents.
Author Jack McCallum provides an enlightening journey through medicine and the military in Epidemics and the American Military: Five Times Disease Changed the Course of War. His book is as much science as it is history. The narrative identifies four key tools for addressing disease spread: quarantine (separating the sick and healthy), ecology (changing the environment in which diseases spread), pharmacology (treating disease externally by applying drugs), and immunology (treating disease internally by stimulating the body's natural immune system, e.g. vaccines and inoculations). It examines each medicinal tool in the context of the American military: the impact of smallpox on George Washington's Continental Army; different responses to typhoid reflecting medical advances between the Civil War and Spanish American War; the aforementioned Spanish Flu and World War I; and malaria in World War II.
McCallum walks the tightrope of any author attempting to tackle a technical subject, trying to provide substantive detail at a level accessible to the audience. The resulting book is largely successful, and is an engaging narrative while only somewhat stretching the reader's recall of high school biology terms. It's the kind of book that professionals must engage with to acquire expertise, because it develops subject matter knowledge and does so in an interdisciplinary approach across both history and science.
Military historians will value the creative approach to examining campaigns they may already be well versed in. Scientists will benefit from seeing the impact of their laboratory studies applied to real-world conditions during warfare. At times bleak for its chronicle of death and disfiguration, McCallum also serves as a reminder about the revolutionary impact of germ theory on medicine, and the harsh ignorance which infectious agents hold for nationalities and combatant/non-combatant status.
With a doctorate in medicine and another doctorate in history, McCallum's interest in epidemiology certainly predates the COVID-19 pandemic, and the recent crisis is primarily acknowledged as a prelude to his broader narrative on disease through military history. If past is prologue, the book itself is a valuable context to the current military thinker wrestling with the aftereffects of COVID-19 and the preparations for the next major biological hazard to come.
In the immediacy of 2020, COVID-19 was discussed in the framework of politics and public health. Half a decade after the initial disease outbreak, the military must consider the pandemic with questions about command, leadership, planning, and workforce readiness.
Institutionally, the U.S. military seemed well prepared for enacting force protection measures in a pandemic. There are clear standards for Mission Oriented Protective Posture conditions, anticipating battlefield biohazard threats. In 2020–21, the highest levels in the chain of command gave unambiguous directives to wear masks and include the COVID vaccine among other mandatory inoculations. However, a limited number of military officers refused to do so, joining in the choices made by some civilian counterparts. Unlike the consequences in civil society, these officers left in their wake the example to subordinates of refusing lawfully given orders; and to the detriment of a chain of command, some of those subordinates now question what other orders they themselves may also refuse.
A non-zero percentage of the defense workforce continues today to have workplace accommodations due to immunological vulnerability of themselves and their families. These range from simply wearing protective equipment to requests for telework/remote work. Managers who don't acknowledge the legitimate health concerns of this demographic risk alienating skilled employees, resulting in sub-par organizational performance and higher workforce attrition.
Many prepandemic military duties presumed high levels of security and were performed in secure compartmented information facilities. This posed challenges for continuing mission operations when offices were shut down in the spring of 2020 and forced rapid innovation in DOD policies and processes to enable remote work. Return to office decisions have sometimes neglected the mission flexibility which remote work created. This risks organizations becoming less agile to continue mission in a future crisis, and it makes them more vulnerable as centralized targets for an adversary.
Perhaps the most significant impact of the pandemic is a generation of youth raised during it and their loss of "normal" experiences. An eighteen-year-old recruited in 2024 as a soldier, sailor, or airman spent 25 percent or more of their high school years learning remotely and physically separated from classmates at a key point in their educational, social, and emotional development. Past assumptions about the skills entering military recruits already have what their responses to traditional training measures will be, and their acceptance for a culture of service may not apply. Frontline leadership may have to become more directly engaged at the entry level to produce the same standard of military readiness that the United States has enjoyed for decades.
The United States is fortunate that in 2020, COVID-19 impacts were felt globally and that the most likely military rivals—China, Iran, North Korea, etc.—had their readiness impacted at a level greater than the United States. Despite concerns, no U.S. adversary took advantage of the moment of U.S. weakness to attack in 2020 as they themselves were also suffering. The pandemic is a reminder that the late twentieth century victories from antibiotics and vaccination campaigns against smallpox, polio, measles, and other diseases is an aberration. Warfare in the future, as it has in the past, may heavily involve biological hazards, either naturally from the aggregation of combatants, refugees, and breakdown in sanitation infrastructure, or intentionally due to adversary bioweapon usage. As the Frontier Army Museum notes, "Innovative healthcare will always be needed in times of war."
Book Review written by: Matthew Kiefer, Fort Leavenworth, Kansas