Tau Ceti IV (a.ka. the Colony) is a planet in the Tau Ceti system. It was the first UESC extra-solar colony, which was colonized by the UESC Marathon before it was destroyed by the Pfhor in 2794. At it's height it housed about twenty-four thousand people.
It flourished for 27 years before the Pfhor attacked it with a scoutship, which was alerted to the human presence by the A.I. Durandal, who was becoming Rampant. Nine Mjolnir Mark IV Cyborgs were on the colony, having been smuggled onboard the UESC Marathon before the voyage to Tau Ceti, turning the tide in the battle for the Colony. While only one of them was aboard the Marathon which was orbiting the colony.
While the initial attack was eventually repulsed, three months after Durandal's departure from the system, the Pfhor returned in force to destroy the entire colony and the Marathon. It is here that they picked up the reanimated Tycho, who would end up working for a Pfhor captain.