1918 influenza pandemic likely spread via US military camps

On March 4, 1918, Fort Riley, Kansas documented a notable influenza case that historians link to the wider 1918 pandemic. Crowded U.S. training camps such as Camp Sherman and packed transatlantic troop ships spread the virus as the United States mobilized roughly 4.7 million service members and sent about 2 million overseas. The outbreak contributed to a global pandemic that killed an estimated 50 to 100 million people and disrupted military operations and postwar recovery.