Fort Sheridan became the main center for cavalry training and later was used as the first training facility for Reserve Officer Training.Center (ROTC).
During World War I it was the main induction center for recruits from Illinois, Michigan and Wisconsin. When the soldiers returned after the war, the Great Influenza Epidemic broke out in 1918 and some 60,000 patients were treated there.
Between wars many changes occurred to the fort to accommodate the new autos, tanks and trucks. Structures previously devoted to horses were converted to the new technology.
During World War II, Fort Sheridan was one of the four Recruit reception Centers in the United States and processed huge numbers of troops. The fort also served as the administrative control headquarters for German POW camps in Illinois, Michigan and Wisconsin. Some 15,000 POWs were incarcerated in those states and quite a few at the fort itself.