When human worlds are threatened, people depend on the Imperial Marines and the Unified Armies -- the Ground Forces. They are the only soldiers most citizens ever see. People may follow orbiting battleships as bright "stars" in the sky, but for the average man it is the Marine in battledress and the imposing bulk of an Army grav tank that embody the Imperium. GURPS Traveller: Ground Forces covers the "ground pounders" of the Third Imperium and their comrades in arms, the sailors of the "wet" navy and the pilots of the Close Orbit and Aerospace Command.