The Marine unit aboard the USS Excalibur-A is not a full unit of Marines as with some stations and ships. Instead, two highly specialized squadrons are assigned to the ship. These squadrons are there to provide support to Starfleet personnel as needed in a variety of situations. Collectively, the dual squadron group is known simply as 'The Knights' of Excalibur, each with their own division colors.
Fighter Squadron & Search and Rescue (SAR) Team (Black Knights)
The Fighter Squadron is housed on Deck Nine, in the fighter bay. The fighter bay is designed for the housing, refueling and maintenance of the fighters. The squadron is made up of seven Eagle class fighters on constant standby. Adjacent to the bay is a turbolift leading directly to the Marine Control Center on Deck Nineteen.
The SAR team is made up of non officers with various skills and lead by one officer. They are equipped with special weapons and equipment, kept in the Marine armory, found in the Security department. The team is used for searches of things from ships to alien installations and for rescues of Federation citizens as well as any others who have need. The team, being made of pilots, medics and combat engineers is capable of handling any situations they find themselves in.
Covert Intelligence Unit (White Knights)
The unit is comprised of specialized Marines with varied backgrounds. Within the CIU are the Intelligence Division, Counter Intelligence Division, PsyOps, and two Black Ops Teams. Each serving a different purpose, but under the command of Brigadier General Maxwell Hayes, their facilities take up most of deck 19. They share the MCC with the Black Knight Fighter Squadron. No Marine in the White Knights has any operational authority on the vessel itself, except in extreme circumstances and only when directly ordered by the vessel CO.
Marine Facility on Deck Nineteen
The main room is the Marine Control Center (MCC) where flight and ground operations can be planned and overseen. The information gathered there is shared automatically with the Bridge stations. Adjacent to the MCC are a handful of offices including the commanding officer of both the Black and White Knights. Deck Nineteen also houses the Marine's Enlisted and Officers Mess, a place where the marines can dine and relax in the company of their fellow marines. A briefing/muster room and a change room can also be found on Deck Nineteen. There is also a turbolift leading directly to the fighter bay on Deck Nine.