The 1918–1919 Influenza Pandemic was one of the deadliest pandemics in world history, infecting hundreds of millions of people and killing approximately 50 million people worldwide. Occurring against the backdrop of World War I, the pandemic added to the horrors and devastation brought on by that conflict.

While it is uncertain exactly how or where the disease originated, the earliest known cases in the United States were reported in Kansas at Fort Riley. With thousands of men stationed together in a relatively small area, away from home for the first time and lacking immunity from the childhood diseases experienced by upbringing in urban areas, the virus spread quickly. Unfortunately, authorities in the U.S. and overseas failed to recognize how lethal the disease could be, leading to its rapid spread through both military and civilian ranks. The constant flow of people, whether on troop transports, supply ships or railroads, easily transmitted the disease. The flu also struck quickly, with a person healthy one minute and sick just a few hours later. With no treatment or vaccine available, little could be done. This first outbreak was highly contagious and spread around the globe in only a few months’ time, leading to its labeling as a pandemic rather than an epidemic. Later in 1918, another wave struck, with peak totals of sick and dead in October and November. A third wave hit in early 1919 and persisted into 1920.

The influenza pandemic had an enormous impact on World War I. Not only did the war spread it more rapidly throughout the globe, the flu also added to the existing military strain by suddenly taking thousands of men out of action - for weeks at a time if they survived. The second wave’s occurrence in late 1918 likely impacted Germany’s ability to continue fighting and influenced the Central Powers pursuit of an armistice. The flu’s connection to World War I, and its historic impact, are exceedingly significant.