Roma D was one of many Known Worlds where the Roman Empire never fell. It was populated by clockwork soldiers that could talk and fight like men; Aeneicus was one such soldier. Their shiners could portray pictures as well as voices, and their cities used a vacuum tube transport system. Its regent committed its fearsome "Ferrum Legion" to the Empire of Empires' war against the Greater German Reich during the War in Heaven. (PROSE: Warlords of Utopia)
As veterans of the eternal war, the Iron Legion was led by General Ironicus in conquering the galaxy. They began to take prisoners from other dimensions to feed the Malevilus as offerings; when the Fourth Doctor encountered them in Stockbridge, he escaped into their reality and programmed the Bestiarus to start a revolution by attacking the Legion at key points throughout Rome. Vesuvius then became the leader of the Galactic Roman Empire. (COMIC: Doctor Who and the Iron Legion)