Thus Diocletian, who ruled from Nicomedia, promoted two faithful legions from the Illyricum (Legio V Iovia and VI Herculia), the area he was also descended from, to be the personal protectors of the Roman Emperors.
The cognomen of the legion refers to Hercules, to whom Diocletian's colleague, Maximian (also known as Herculius, "the man like Hercules"), was devoted and identified.
VI ''Herculia'' | Legio XVIII | Legio XVII | Legio XV Apollinaris | Legio XIX | Legio V ''Iovia'' | Legio V Iovia | Legio VI Herculia | Legio VI Ferrata | Legio II Augusta | legio VI Ferrata | legio III Gallica | Legio XX Valeria Victrix | Legio XIV Gemina | Legio X Equestris | Legio VI ''Ferrata'' | Legio IV Scythica | Legio II ''Augusta'' | Legio I Adiutrix |