- You may be looking for the Millennium Wars instigated by Melanicus.
The Millennium War was an epic war that occurred about 150 million BC. It involved most of the advanced races then extant.
This war was started by the Constructors of Destiny, an ancient race which evolved billions of years BC. They were considered gods and affected the development of the early universe and such worlds as Earth and Gallifrey. Eventually, the Constructors of Destiny developed a computer that was built into the very universe and could discover the ultimate truth. Despite the protests of a Time Lord from the future and the Xeraphin, the Constructors of Destiny created the Great Attractor. After it was turned on, its mind snapped and it annihilated its builders. It created an army using Block Transfer Computations, which set out to gather the knowledge to turn the Mad Mind into a god. It took over all the robotic races almost immediately.
The living races in the universe were forced to band together to defeat this army. This army, made of over a thousand fleets from as many planets, set out to try to stop the Mad Mind of Bophemeral. (PROSE: The Quantum Archangel)
The Millennium War lasted over a thousand years. Among the key events were:
- The first move was by the Dæmons, who stopped the Mad Mind from using a dark matter cloud in the Rift of Perseus.
- The Osirans stopped the Mad Mind from creating a wormhole in the Horsehead Nebula, which would have killed quintillions.
- The Euterpians and Greld, using the battle shroud of the Semquess and wielding the Omnethoth, destroyed an entire galaxy to destroy a thousand of the Mad Mind's fleets.
- The Kastrian fleet was utterly destroyed and Kastria was ravaged when the Mad Mind turned their computers against them.
- The Exxilons joined forces with the Uxarieans to destroy the fleets within the Andromeda Galaxy. They were caught in a trap that led to their downfall and the eventual destruction of the Crab Nebula.
- The Sontarans and the Rutans, despite their long-standing enmity, joined forces to attack a drone factory in a pincer movement. Their entire army was blasted into a black hole within seconds.
- The Grey Hegemony and the Influence of Light attempted a psychic attack on the Mad Mind, but they were both mentally damaged in the attack.
- The Time Lords, led by Rassilon, eventually ignored their non-intervention policy and joined the fight. The Maskmakers of the Pageant, the Faction Paradox, and the Ministers of Grace also came from the future to help the war effort.
The final event of the war was fought against the Mad Mind itself. The Nimon, with support from the Osirans, dropped ten million quantum collapsars into the Mad Mind. When the Mad Mind was breached, the Time Lords caught it in a time loop, forcing it to repeat the same nanoseconds over and over again. (PROSE: The Quantum Archangel)
After the war, the survivors met at the Midnight Cathedral on the Moon to consider the aftermath. They asked the Guardians of Time to erase their memories of the Millennium War, which they did with the Key to Time; to date, the only person known to remember the War is the Doctor, whose memory of it was restored by Kronos when the Quantum Archangel sought to release the Mad Mind so the Doctor could prevent its return. (PROSE: The Quantum Archangel)