By the early 26th century, androids were commonplace in Earth Empire society, but were viewed as an under-class. The androids finally became fed up with the situation and moved en masse to the relatively unused Orion System. They set up their own government, with the stipulation that humans living in the system could stay if they accepted android rule. The Earth Empire considered this a violation of sentient rights, and attacked.
After eight years of fighting, the war had reached a stalemate; to break it, the Earth Military sent an agent to the Garazone System to retrieve Cyber-Technology from a derelict Cyberman Star Destroyer, abandoned in the Cyber-Wars a generation earlier. The Eighth Doctor stopped the agent from retrieving the technology and kept the reactivated Star Destroyer busy until it was destroyed by a local ion storm. (AUDIO: Sword of Orion)
The Earth Military found another source, and tried to create their own Cybermen to use against the androids. It turned out to be yet another plot by the Cybermen to take over Earth. Forces from the Earth Military narrowly avoided the Cybermen reawakening in their vaults in Telos. (AUDIO: Cyberman)