Wars Where Diseases Killed More Americans Than Combat

During the American Revolution, diseases impacted the course of the war and the outcome of many battles. More soldiers died from diseases – including smallpox, malaria, typhus, measles, and dysentery – than from combat. This was due to a number of factors, including the unsanitary conditions of the camps and the lack of medical knowledge on treating certain diseases.

In the Napoleonic War era, the War of 1812 was fought on land and sea between the United States and Great Britain. American interests included protecting its shipping rights, while Great Britain was attempting to stop the U.S. from interfering in its war with France.

During the war, diseases like typhoid fever, pneumonia, malaria, measles, and smallpox killed more soldiers than combat. These and other diseases, which accounted for about 75% of American troop fatalities, not only took a toll on the soldiers, but also on troop morale.

In the Mexican-American War, nearly 11,000 American servicemen died of disease, accounting for about 88% of U.S. military deaths. Infectious diseases, including dysentery, yellow fever, and, often spread through contaminated food and water, and because of crowded living conditions and poor sanitation and hygiene practices. Diseases ultimately impacted the American tactics and strategy in the war and eroded morale.

The Civil War was the deadliest war in U.S. history. While estimates range, a widely accepted figure is of around 620,000 Union and Confederate fatalities. Though over 200,000 soldiers were killed or mortally wounded on the battlefield, with many others dying of starvation, diseases accounted for the majority of Civil War deaths.

Many of the soldiers left their communities for the first time to join the war effort, exposing themselves to diseases for which they had no developed immunity. Diseases that ravaged the armies of both the North and the South during the war included intestinal disorders such as typhoid fever and dysentery, as well as various fevers, measles, and smallpox.

For every American soldier killed on the battlefield in the Spanish-American War, nearly seven died from disease. Unsanitary conditions at military camps and poor hygiene among troops allowed for the rapid spread of diseases like typhoid fever and dysentery. Diseases like yellow fever were also spread by mosquitoes among U.S. troops stationed in Cuba.

The Philippine-American War, which lasted from early 1899 to mid-1902, resulted in the deaths of 4,300 American servicemen – nearly two-thirds of whom died of disease. On the Pacific Island nation, located more than 8,500 miles from Washington, D.C., outbreaks of cholera, dysentery, and malaria were devastating to American forces who were fighting to maintain control of the country the U.S. had recently purchased from Spain, following the Spanish-American War.

World War I was the final war in which more Americans died from disease than combat. Of the 4 million Army hospital admissions during the war, a reported 86.3% were due to disease. Though by the time the U.S. joined the war effort, advances in water treatment and vaccines greatly reduced instances of diseases like dysentery and typhoid, the global outbreak of influenza, known as the Spanish Flu, alone killed an estimated 45,000 American troops. Military hospitals were also overwhelmed by more than 23,000 cases of tuberculosis during the war.