By 3999, Earth had many enemies including Beaus, Malpha, Zephon, and the Eminence Gris. The Empire's key to power was the Great Clock on Earth which served as a counter-weight for hyper lanes, guarded by the Guardian of the Solar System, Mavic Chen. When the Clock was destroyed, (AUDIO: The Guardian of the Solar System) Chen joined the Outer Galaxies in the Great Alliance with the Daleks to destroy Earth, planning to betray them. The plot was defeated, however; Chen was killed, and the Outer Galaxies and Earth turned against the Daleks (TV: The Daleks' Master Plan) beginning the Great War. (PROSE: The Evil of the Daleks)
By the 42nd century, it had spread from an overcrowded Earth throughout the Mutter's Spiral, the Andromeda Galaxy, and another galaxy. The currency of the Empire was the credit. (TV: Planet of the Ood) The Torchwood Archive was consulted by the Empire's rulers, though came to be sidelined.
At one point the Torchwood Archive became aware of an imminent coup against the ruling Empress, however she ignored their advice and ultimately fell victim to the coup, being killed along with her children. Years later the coup fell and Merdiven claimed the throne as Emperor, claiming to be a surviving child of the late Empress. In actuality he was the soldier who had killed her family and he arranged the opening of the late Empress' library at the Great Cobalt Vault to lure and killed members of the court who might realise the truth. The Torchwood Archive sent Zachary Cross Flane and Chloe who survived the intial attack by the robot waiters and realised the truth about the Emperor. Citing that Torchwood's loyalty was to the Empire, not the Emperor, Zachary left Merdiven trapped in the late Empress' library. (AUDIO: Empire of Shadows)
One of the farthest reaches of the Empire was Agelaos. (PROSE: The Weeping) The Empire also launched the Walker Expedition to Krop Tor, unknowingly playing into the hands of The Beast. (WC: Tardisode 8)