"The Citadel" is a military school, I think tied to the Marines. But more of like a JROTC thing that some people take real serious. I don't think they're actually in the military.
I was Navy stationed in Charleston and they'd always be out in their uniforms with giant egos.
It is a private military academy - think West Point, but a private school. Students are basically officially ROTC, but unlike ROTC at a normal university, it’s a full time thing with both daily and formal uniforms, marches, etc.
Like West Point, Citadel grads form an old school ties network in the military.