Ft. Riley, Kansas where the first major outbreak of the 1918 influenza hit in the United Sates, after it was brought to the United States from China earlier that year. Chinese laborers were imported to serve the British and French military efforts in WWI. They traveled through the United States and brought this disease with them, spreading it to the troops in Fort Riley the spring of 1918. While World War I did not cause the flu, the close troop quarters and massive troop movements hastened the pandemic and probably increased transmission, augmented mutation and may have increased the lethality of the virus. Some speculate that the soldiers' immune systems were weakened by malnourishment as well as the stresses of combat and chemical attacks, increasing their susceptibility.