USS Springfield Marine Detachment

The Marine Detachment or MarDet is a unit of United States Marines aboard large warships including cruisers, battleships, and aircraft carriers. They were a regular component of a ship's company from the formation of the United States Marine Corps until the 1990s. Missions of the Marine Detachment evolved over time, and included protecting the ship's captain, security and defense of the ship, operating the brig, limited action ashore, securing nuclear weapons and ceremonial details.

History
Marines served aboard sailing ships as a small amphibious force able to capture and hold minor port facilities as required for protection of American interests. Marine sharpshooters were often stationed in the rigging during ship-to-ship combat to fire at officers and helmsmen aboard enemy warships. Marines often operated naval artillery during general quarters when the distances of gunnery engagements exceeded the range of small arms.