Since 1800 the Marines have been in the forefront protecting American lives and property. In 1835, we can find the first recorded instance of direct protective support of an American diplomatic mission. During the next 70 years, scores of landings were made by Marines to provide this protective support to foreign service missions and American communities in periods of unusual turmoil. Because of the increased intelligence activities of various foreign nations following World War II, it became apparent to Congress that a pressing need existed for around-the-clock protection of United States diplomatic missions abroad by alert and reliable American personnel. This need was enacted into law with the passage of the Foreign Service Act of 1946. "The Secretary of the Navy is authorized, upon the request of the Secretary of State, to assign enlisted members of the Navy and the Marine Corps to serve as custodians under supervision of the Principal Officer at an Embassy, Legation or Consulate". This provision has been incorporated in 10 U.S.C. 713 by the 34th Congress.

Under the legislation, the Secretary of the Navy placed the responsibility upon the Marine Corps to provide enlisted Marines who meet the Department of State's security guard requirements at Foreign Service posts throughout the world.