David Kopel of the Volokh Conspiracy has a nice blog post on the Maryland State Guard. The Maryland State Guard was initially created to provide homeland defense during World War II. From Kopel:
With the Army and the National Guard busy overseas, homeland defense was the responsibility of the rest of the American public. On March 10, 1942, Maryland’s Democratic governor, Herbert O’Conor, called forth the militia of Maryland. In a radio address to the People of the State, O’Conor called for the creation of the Maryland Minute Men.
The Maryland State Guard has since evolved into the Maryland Defense Force, a peer institution of the Maryland Army National Guard, Maryland Air National Guard, and the Maryland Emergency Management Agency.
Image by Maryland National Guard / Flickr.