A medical ward during the influenza epidemic at Naval Hospital Mare Island, California, November 1918. Courtesy of the Australian Emergency Management Knowledge Hub.

The influenza pandemic took a terrible toll on all its victims. One group hit particularly hard was the United States military. Of the more than 100,000 American World War I military deaths, more 60,000 died for non-combat reasons including the largest portion from influenza. During September-November of 1918 alone, an estimated 20 to 40 percent of US military servicemen took ill and died from influenza.

After their initial overconfidence in their knowledge of the disease, medics, nurses, and chaplains were soon compelled to don surgical masks at all times to avoid becoming ill themselves. Every soldier, medic, or nurse taken ill cost the military valuable service time as well—the War Department estimates that overall the war effort lost 8,743,102 days to influenza among enlisted men in 1918.