Service to the Armed Forces began during the Spanish-American War, when Salvation Army officers accompanied troops to the Philippine Islands. In 1917, National Commander Evangeline Booth initiated a program that ministered to the needs of American military men at home and abroad. In the program, female Salvationists became known as "Sallies" as they served donuts and coffee in the frontline trenches and elsewhere. They became a symbol of love and caring that has endured through the years.

In 1939, as World War II appeared inevitable, The Salvation Army helped create the interfaith movement that led to the formation of the United Service Organization, known as USO.