Active duty also applies to a person who is a cadet attending one of the five United States Military Service Academies. Active duty applies to service in the military Reserves or National Guard only if the person has been called up for active duty, mobilized, or deployed. Service as a civilian employee or civilian volunteer for the Red Cross, USO, Public Health Service, or War or Defense Department are not considered active duty. For Merchant Marine service, only service during World War II is considered active duty, and no other period of service.