The history of the MDDF dates back to colonial days in the 17th century, but it was formally established in 1917 with the mission "to protect public buildings, water supplies, and other properties". It was called the Maryland State Guard. It was disbanded in 1920 to make room for the National Guard to return to duties in the armories. The Maryland State Guard was reactivated in 1939 in response to World War II. It was then deactivated in 1947. As of 1983, the Maryland State Guard was reactivated and renamed the Maryland Defense Force. In 1994, the Maryland Defense Force's missions were expanded to search and rescue, armory staffing, and disaster relief. As of September 11, 2001, the Maryland Defense Force was tasked with its current mission, which is to provide support to the Maryland Military Department as needed.