It is believed that the epicenter of the Spanish influenza was actually in France in 1918. Early reports, however, show that it first showed up in the United States at Fort Riley in Kansas and in Haskell County, Kansas. Due to the movement of troops during World War I, the Spanish flu quickly spread. Soon it had spread to northern France and to Sierra Leon in Africa. Within a year, the flu had spread all over the world. The First World War was a major contributor to the spread of the disease. Travel between North America and Europe was more frequent. Soldiers traveled to the front and back home, bringing the disease with them. Supply ships also went back and forth.
The first phase of the Spanish flu resembled the common seasonal flu. Elderly people and those in poor health were more likely to become sickened by it. In the second phase, young people and healthy adults frequently became ill. Many died from the Spanish flu. World War I also contributed to the development of a more serious strain of the flu. In peacetime, people who were ill stayed at home under the care of a doctor. Soldiers fighting in the war were already suffering from horrific conditions. They lived in muddy trenches, in close quarters with other soldiers. When they became ill, they could not easily be isolated. There were already not enough doctors to treat wounded soldiers.
In all, the Spanish influenza killed millions of people around the world. Some estimates suggest that as many as one hundred million people died. It had a devastating impact on people all over the world.