Alpha Halo — ALPHA HALO

**HOST PLANET:** *Threshold*
**HOST STAR:** *Soell*
**STATUS:** *Destroyed (Battle of Installation 04*, *2552*)

POPULATION: 0
SPECIES: N/A

ANCIENT HISTORY

Alpha Halo, formally Installation 04, was one of seven Halos in the Neoteric Halo Array. It was positioned in the Soell system, orbiting the gas giant Threshold, and operated by the station's monitor 343 Guilty Spark. At the tail end of the Forerunner-Flood War in 97,445 BCE, Alpha Halo was fired for the only time as part of the Great Purification that cleansed the galaxy of all sentient life and eliminated the Flood threat.

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Jan 3

Forerunner-Flood War

~97,745 BCE - 97,445 BCE

The Forerunner-Flood War was a military engagement between the Forerunner species and the Flood that took place over approximately three-hundred years from 97,745 BCE until 97,445 BCE.

Jan 3

Great Purification

~97,445 BCE

The Great Purification was the final event of the Forerunner-Flood War, purging the entire Milky Way galaxy of all sentient life, including Forerunners, the Flood, and any other species that may have survived the Flood infestation.

MODERN HISTORY

The installation remained undiscovered until 2552, when the smart AI Cortana, using data recovered from Forerunner artifacts, plotted a course for the UNSC Pillar of Autumn away from the recently glassed Reach and ended up at Alpha Halo. During the Battle of Installation 04, the Flood was released, forcing John-117 and Cortana to destroy the ring by detonating the Pillar of Autumn's reactors. A piece of Alpha Halo, known as Alpha Shard, made an emergency jump through slipspace and ended up in the Orrichon system, where a particular material was harvested from its surface and used as a bio-weapon before finally being neutralized by an ONI team.

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Sep 19

September 19, 2552 – September 22, 2552

Battle of Installation 04

September 19, 2552 – September 22, 2552

The Battle of Installation 04 was an engagement between the UNSC Pillar of Autumn and the Covenant Fleet of Particular Justice on and around the Forerunner megastructure known as Installation 04, or Alpha Halo, in the Soell system.

September 19, 2552 – September 22, 2552

Oct 24

October 24, 2552

Skirmish on Mona Lisa

October 24, 2552

The Skirmish on Mona Lisa was a minor conflict that occurred in the debris field of Installation 04 in the Soell system aboard the prison ship Mona Lisa between UNSC forces and an outbreak of the Flood on October 25th, 2552.

October 24, 2552

Feb 8

February 8, 2556

Mission to Alpha Shard

February 8, 2556

The Mission to Alpha Shard was a joint ONI and Sedran Colonial Guard mission to secure and eliminate the source of the bio-weapon used in the Sedra City Mall Bombing in February 2556.

February 8, 2556