Fall of Aiur

The Fall of Aiur was the zerg invasion of Aiur, the homeworld of the protoss, and one of the decisive events in the history of the species and of the war between protoss and zerg. It began with the descent of the Overmind and the bulk of the Swarm onto the planet and unfolded at the same time as the Protoss Civil War, the internal conflict between the templar Tassadar and the ruling Conclave. The war ended when Tassadar destroyed the Overmind, but by then the damage was done: the zerg had overrun most of Aiur, slain seventy percent of the protoss population, and left the survivors no choice but to abandon their world. Despite the loss of the Overmind and many of its cerebrates, the zerg were the victors.

Background#

The conflict began soon after the protoss discovered the presence of zerg near terran colonies. The protoss opened the war by sending an expeditionary force to destroy the zerg infestation of Chau Sara. The preliminary campaign failed, and the protoss were unable to save the heavily populated terran world of Tarsonis from a massive zerg invasion.

Executor Tassadar was ordered to return to Aiur, but instead followed a psychic beacon to Char, the zerg base of operations. There he made contact with the Dark Templar, an outcast protoss sect, and together they learned how to slay the zerg. In the process the Overmind learned the location of Aiur. Tassadar's force was stranded on Char and could not prevent the coming invasion. While there, the dark templar and Tassadar's templar allied with a band of terrans, Raynor's Raiders.

The zerg invasion#

The Overmind and the majority of the Swarm descended upon Aiur. One of the Swarm's first tasks was to acquire a khaydarin crystal, which was defended by the Vanguard of Aiur. The Vanguard was defeated and the crystal claimed. The zerg then destroyed an ancient temple that marked the spot where the xel'naga had first set foot on Aiur, defeating a second Vanguard force to do so, and set the crystal in its place. This enabled the Overmind to crash-land on the planet and hold a physical form there.

The protoss were demoralized by their recent losses but immediately tried to retake territory. They fought the zerg to a standstill while suffering severe losses. The Conclave, believing it was winning, sent an expedition to arrest Tassadar over his association with the exiled Dark Templar, whom it considered more dangerous than the zerg. Instead, Tassadar took command of these troops and used them to rescue Dark Prelate Zeratul from the zerg.

The Protoss Civil War#

Tassadar returned to Aiur with a number of dark templar, intending to destroy the Overmind with their powers. This brought him into open conflict with the Conclave and the Vanguard of Aiur, opening the Protoss Civil War alongside the wider invasion.

Tassadar's forces devised a plan to weaken the Swarm. They sent Zeratul to slay two cerebrates commanding broods near the Overmind, intending that their deaths would distract the Overmind and thin the zerg standing between the protoss and their target. The plan succeeded. Together with Raynor's Raiders, the protoss launched a final assault on the zerg, and Tassadar sacrificed himself to destroy the Overmind.

The retreat#

The destruction of the Overmind did not save Aiur. The planet had been left a smoking ruin, and the zerg rampaged across it, destroying seventy percent of the protoss population, including the Conclave.

Zeratul convinced Judicator Aldaris that the Khalai refugees should retreat to the last functional warp gate on Aiur and flee through it to Shakuras, homeworld of the Dark Templar. Zeratul personally led troops to and through the gate, but hundreds of thousands of protoss were killed during the evacuation. Fenix and Commander Jim Raynor volunteered to guard the Aiur side of the gate from the zerg. Large numbers of protoss fled over the course of three days, until Fenix and Raynor were forced to close the gate to stop the zerg from forcing their way through to Shakuras.

Abandonment and the survivors#

The protoss stranded on Aiur scattered in a panic. One group, led by Fenix and Jim Raynor, remained near a warp gate and was later hit hard by the invading United Earth Directorate. During the Fall, high templar Erekul summoned motherships from the edge of protoss-known space; the fleet assembled after the evacuation and tried to rescue stranded protoss, but could not locate those who had fled.

The settlers on Shakuras launched at least two return expeditions to Aiur. One, led by high templar Rihod, former high templar Lekila, and a Dark Templar ship commander, searched the Velari Templar School for the powerful Kassia crystal; under siege by the zerg, Lekila and Rihod fused into a twilight archon to carry the crystal back to their ship.

One group of survivors, calling itself the Shel'na Kryhas, meaning "Those Who Endure," gathered under the templar Ladranix and sheltered in the ruined cities of Antioch. The Shel'na Kryhas later lost many members to a splinter group, the Tal'darim, meaning "The Forged," led by Felanis. The Tal'darim took shelter in caverns beneath Aiur that the Conclave had forbidden thousands of years earlier, where they worshipped a hidden "Benefactor" they called the "Xava'tor" and were controlled by a drug known as Sundrop. They learned to capture zerg and suffered fewer losses than the Shel'na Kryhas, which drew many defectors. Years after the abandonment, only hundreds of Shel'na Kryhas, including just three templar, still remained, while the Tal'darim were in truth being culled by the dark archon Ulrezaj.