The United States Navy Armed Guard were US Navy Gun crews consisting of Gunners, Coxswains and Boatswains, Radiomen, Signalmen, an occasional Pharmacist, and toward the end of the war a few radarmen serving at sea on Merchant Ships.

The US Merchant Marine ran the ships and the USNAG provided gunnery protection and communications services. The Merchant Marine occasionally served as loaders or ammunition handlers but very seldom manned a gun.