Army - 6th United States Army - Battle of Phil - World War II with Pacific Service Ribbons - MugSixth Army is a theater army of the United States Army. The Army service component command of United States Southern Command, its area of responsibility includes 31 countries and 15 areas of special sovereignty in Central and South America and the Caribbean. It is headquartered at Fort Sam Houston. The Sixth Army saw extensive service in the South Pacific during World War II, including in New Britain, New Guinea, and the Philippines. Postwar it served