Nine Gallifreys

The Nine Gallifreys or Nine Homeworlds project involved the crypto-forming of eight planets into cloneworlds of Gallifrey during the War in Heaven. (PROSE: The Shadows of Avalon, The Book of the War) However, the count of "nine" was implied to be an understated misnomer, as each secondary Homeworld created its own tertiary Homeworlds; some House Military strategists hoped this would end in every planet in the universe being turned into a Homeworld. (PROSE: The Book of the War)

Creation
The Nine Gallifreys project was originally planned by Greyjan the Sane (PROSE: The Ancestor Cell) and was spearheaded by House Mirraflex's Lady Armourer Mantissa and House Lineacrux four-hundred years later. (PROSE: The Book of the War)

Officially, each Homeworld was run by a caretaker House as a potential replacement if the original Homeworld were destroyed. However, many of the backup Homeworlds actually acted as decoys, with each having its own War King or War Queen and thinking it was the original.

There was a supposedly-total ban on contact between Homeworlds, but Mantissa eventually went into exile on one of the duplicates, (PROSE: The Book of the War) and by the time of the fall of Mictlan, travel between Gallifreys was often performed by the Lord President and his agents. However, even then, not even the President knew which was the original. (PROSE: The Taking of Planet 5)

Some Gallifreys were hidden in pocket universes; (PROSE: The Taking of Planet 5) one Great House (AUDIO: The Eleven Day Empire) notably created a homeworld on Christine Summerfield's Earth in the bottle universe. (PROSE: Dead Romance) A human colony-world was cryptoformed by the Great Houses into a Homeworld between 3560 and 3591, and some of its inhabitants like Verrifant were mutated into regen-inf soldiers. (PROSE: The Book of the War)

Six years before the Cataclysm, the War King became President of what purported to be the original Homeworld, and he continued in that role for over half a century. (PROSE: The Book of the War) When Compassion became the first 102-form timeship two years before the War, (PROSE: The Book of the War) Romana was also War Queen and "Mistress of the Nine Gallifreys" on what seemed to be the original Gallifrey. (PROSE: The Shadows of Avalon, The Ancestor Cell)

The Book of the War speculated that the original Homeworld could have been moved from its original location and replaced with a cloneworld. (PROSE: The Book of the War) Romana III's Gallifrey was located in Kasterborous. (PROSE: The Ancestor Cell, The Gallifrey Chronicles)

Sometime after the wiping of the original Gallifrey, Homunculette was taught the basics of escapology by War Cardinals at a training complex on Gallifrey XII. (PROSE: Alien Bodies) Homunculette and the Lord President once visited Gallifrey Eight, which contained loomstacks and chronoforges to create weapons and soldiers for the Time Lords; D-Mat Guns were stored on Gallifrey Nine. (PROSE: The Taking of Planet 5)

A group of Oldblood Great Houses created many "lesser Homeworlds" which fought simplified models of the War in bottle universes and oxbow realities. (PROSE: A Prelude to a Prelude)

Destructions
In her lecture "The Cultural Impact of War-Time", Entarodora noted that more Homeworlds had been lost "than might be thought prudent". (PROSE: The Brakespeare Voyage)

The incident where a Gallifrey was first lost was called the battle of Mutter's Cluster. At the time, this brought the "official" total down to nine. (PROSE: The Taking of Planet 5)

Romana III's Gallifrey was invaded by Faction Paradox and destroyed sometime before the Eleven-Day Empire was destroyed (PROSE: The Ancestor Cell) in the War's fiftieth year; (AUDIO: The Shadow Play) at that time, the Faction claimed to have written that version of Gallifrey's backups out of existence. (PROSE: The Gallifrey Chronicles)

Most Time Lords perished in the wiping of the original Gallifrey. (PROSE: Alien Bodies)

Several planets appeared to be the remnants of ruined Homeworlds: the legendary world Ardethe in the constellation Kaster Major was populated only by the Shabooj'm; (PROSE: Deadfall) the lifeless planet New Alexandria had the same coordinates as Gallifrey; (PROSE: The Crystal Bucephalus) Winkle's Wonderland occupied the ruins of Rassilon's Foundry toward the end of the universe. (AUDIO: Zagreus)

Christine Summerfield visited a ruined and deserted Homeworld after escaping the bottle universe. (PROSE: Dead Romance)

At least one Homeworld was predicted to be destroyed upon the destruction of the Hydra-Centaurus cluster by the Grandfather's Maw around the year 60,000,000,000. (PROSE: The Brakespeare Voyage)

Despite the destructions of so many Homeworlds, Entarodora argued in her lecture that the total number of War-time deaths by Great House members was nonetheless small because the inhabitants of these other Homeworlds were "mere-sheath echoes" of a "core probability". (PROSE: The Brakespeare Voyage)

When the Eighth Doctor used the Moment to end the Last Great Time War, it was "Gallifrey Original" which convulsed and burst into flame as it was destroyed. (PROSE: Doctor Who and the Time War) In another account, it was the Doctor's next incarnation who (almost) used the Moment to destroy his Gallifrey, with no hints of there being any others. (TV: The Day of the Doctor)