Over the years I have had the opportunity to meet and work with a range of military personnel, and it is the Marines who blow me away with the level of their knowledge about martial arts. They understand it from both the physical and psychological levels. Many of them train at MA schools in Okinawa and other overseas locations.
I know Army personnel with that level of knowledge as well, it's just seems more imbedded into the Marine traditions.
Be nice, until it's time to not be nice.