The Prosperan Army is actually a loosely tied together organization mostly comprised of planetary self-defense forces and garrisons. The Prosperan Army is the overarching term for all military personnel that are not trained for ship-to-ship combat. While there is a high command and a ranking structure, every army unit outside of Phase 1 colonies are self-defined and self-sufficient. Local army units recruit from the local populace, and remain on planet their entire career. Only very rarely do army units get requisitioned by the Navy for actual wartime work, typically when a Marine division needs to be bolstered for anti-insurgency operations on a nearby planet.
The Army stems from the traditional Prosperan Army of the dark [era] as well as the army post-unification, the Republican Guard. The Guard ensured the continuity of unification and put down near and far rebellions. They also acted as colonial police forces up until the creation and expansion of the Prosperan Marines, at which point the army was pushed to first merely being the defense force of Prospera, and then becoming the basic defense force of all planetary land forces.
The Army is trained and equipped to a lesser degree than the Marines in most cases, with the exception of the Republic Guard on Prospera, and certain other state militaries of more wealthy planets. An Army unit is generally equipped with carbines, suited to urban warfare, or long rifles for wilder planets. Army units also specialize more heavily in armored brigades, using tank and armored cavalry effectively alongside infantry units, in comparison with the Marines who rarely if ever use vehicles. On the contrary, Army units very rarely field Battle Dress.
The Army varies widely in population, as every planet has some form of military, but population between planets is very different. On the average planet, the army will make up approximately 1.5% of the population, while planets with more civil unrest, dangers, or paranoid leaders may have a military reaching 5 or 6%.