United Earth Directorate (formerly) and numerous other factions
Urthos III is a small, mineral rich moon within the Koprulu Sector. It was one of the most fiercely contested territories during the UED Conflict. It changed hands so often (and in such a bloody fashion) that the area eventually became known simply as the Meatgrinder. Thousands died there in pitched battles that often involved multiple forces from each species. Even today, the area is constantly visited by those seeking minerals to fuel their war machines.
Meat Grinder. StarCraft Compendium Map Archives.