Installation 05 Flood outbreak

The Gravemind built by the Flood during the Delta Halo outbreak.

"I wonder about the things the Forerunners did not plan for. Is it perhaps possible that we have not heard from any of the other monitors because they reached the [inevitable conclusion] that what is contained within their installations should not be caged? Have they already acted upon that [belief]?"

— 2401 Penitent Tangent discussing the Flood with 343 Guilty Spark.

A large-scale Flood outbreak occurred on Installation 05 in the hundred millennia between the firing of the Halo Array and the modern day. The outbreak occurred due to a failure of the containment facilities on the ringworld, which was further propagated by the lack of attention by, and accelerating rampancy of, the ringworld's monitor, 2401 Penitent Tangent. The monitor's inattentiveness allowed the Flood to spread rapidly and reach the Coordinated Stage, building a full-grown Gravemind which was able to capture the monitor and gain some control over the ringworld's systems.

History

Background

In 97,445 BCE, the Halo Array (including Installation 05) was fired, sterilising the galaxy of life and ending the Forerunner-Flood war. At this point 2401 Penitent Tangent was left alone on the ringworld as its monitor, similarly to the other installations. As with the other installations, Penitent Tangent was seemingly afflicted by the effects of rampancy as a result of his isolation, though he remained lucid enough to uphold his duties. By the time of the first scheduled maintenance check-in between the monitors of the Halo Array, centuries after the rings had fired, only Penitent Tangent and 343 Guilty Spark of Installation 04 were in contact.

Due to the limited bandwidth available for FTL communications, the two monitors' messages were slow and limited, with simple conversations taking centuries. Thanks to his emerging rampancy, Penitent Tangent demonstrated some unique deviations from Guilty Spark's interpretation of the directives left for them by the Ecumene Council such as refusing to provide a status update on his installation until all monitors of the array were present and accounted for.

The outbreak

Delta Halo's Flood containment facilities were predominantly located in the swamplands, to dissuade outside meddling. This site was one of the first to be breached by the Flood, leading to the formation of a Gravemind.

What is known of the early outbreak on Installation 05 largely comes from second-hand sources: communiques between Penitent Tangent and Guilty Spark, and a series of reports filed by the ancilla of a Flood Cold Storage facility on the ring. As such, the precise order of events is difficult to exactly lay out.

At the end of the first conversation between Penitent Tangent and Guilty Spark, the former took his leave, noting that an "urgent matter" required his attention—presumably the initial breach of the Flood from containment. The initial Flood outbreak was seemingly a mechanical failure of the Cold Storage Flood containment facility systems. Based on a series of reports filed by the submonitor of the facility, the outbreak occurred due to a mechanical failure of the Flood containment facility's containment systems. The facility sub-monitor responded by sealing off all ingress/egress points and reduced the facility's temperature and pressure to conditions unsuitable for Flood growth, requesting assistance for containment cleanup. No response came from Penitent Tangent, and as a result the submonitor repeated its containment failure reports.

After 290 years of no response, the Flood were able to breach the containment facility's local slipspace translocation grid; as a result the facility monitor altered the teleporters into a recursive mode, meaning that any attempt to use them would only lead back into the containment area. At this point the monitor formally reported Penitent Tangent for dereliction of duty. Evidently, the local Flood outbreak was able to spread enough that it began to affect Penitent Tangent via the logic plague, by this point possibly having began to mature into a Proto-Gravemind or Gravemind. In communications with 343 Guilty Spark, Penitent Tangent began to propose that firing the Halos and interring the Flood had been the wrong decision, and that the lack of word from the other monitors of the array was because they had reached similar conclusions. He also began interrogating Spark for information on his previous life as a human, of which Spark had no memory, and for information about the Primordial. When Spark refused to give way, Tangent instead began talking with the emergent-Gravemind on Delta Halo to gain the information he sought.

The interior of the cold storage facility which saw a containment failure.

Penitent Tangent's final communication with 343 Guilty Spark was around 92,872 BCE, 4,573 years after the initial firing of the Halo Array. In his final communications he expressed more obvious signs of logic plague corruption from his conversing with the Gravemind, now expressing a regret in the Forerunners' ancient genocide of the Precursors, and his belief that the Flood had been sent both as a punishment for the Forerunners' sins, and that they would inevitably return to consume the entire universe. The transmissions grew increasingly more garbled and incoherent, with the final informing Spark that he had planted a "seed" on Installation 05—presumably starting to aid the growth of the Flood outbreak on his ring. After this point Guilty Spark received no further communications from Installation 05, and the Flood outbreak was in progress.

By around the year 2335 CE, 99,779 years and 204 days after the initial firing of the array, the site of the containment breach was forced to restore its temperature and pressure to normal values as the environmental seals keeping it secure were beginning to fail. By this time Installation 05 had not been visited by any visitors, leading the facility ancilla to suspect mechanical failure over sabotage. Eventually the Gravemind was able to gain access to the facility, and the ring's, slipspace translocation grid. In its final known report, the ancilla once reported Penitent Tangent to authorities on Installation 00 for dereliction of duty. In reality the monitor had been captured by the Gravemind and held in its clutches.

The Sentinel wall and containment shield surrounding the Library.

In the millennia since initial breach, Penitent Tangent's lax attitude toward containment meant that the Sentinels of Installation 05 had no central coordinating force to manage the outbreak. The Flood were able to establish a Gravemind beneath the installation's Library, leading to the establishment of the Sentinel wall and quarantine zone around it to keep the Flood in.

Modern outbreak

Main articles: Battle of Installation 05, Great Schism

By 2552, the Delta Halo outbreak had reached something of a stalemate—the Flood were trapped inside the quarantine zone, and the Sentinels were seemingly-unable to fully root them out. Notably though, the Gravemind's tendrils were able to reach significantly outside of the quarantine perimeter. In early November of that year, the arrival of human and Covenant forces at the ring allowed the Flood to spread once more. During the battle of Installation 05 forces from both sides breached the quarantine perimeter in a race to retrieve the installation's activation index from the Library, supplying the Flood with a new source of biomass to prey upon alongside advanced weapons and vehicles to use in combating the Sentinels. The fighting escalated rapidly and the Gravemind was able to capture a human Stalwart-class light frigate, UNSC In Amber Clad, which it used to escape the ring and spread to the Covenant's capital city-station High Charity—propagating the outbreak on an unimaginable scale amid the Covenant's collapse into civil war. The Flood's spread was further aided by agents of the Governors of Contrition, some of whom let themselves—and their followers—be consumed by the Flood. The risk posed by the Flood gaining control of Covenant starships meant that Sangheili and Jiralhanae forces formed temporary truces with one another to focus their efforts on destroying infected ships.

At this time Cortana used the aborted firing of Installation 05 during the battle to send a signal back to human space warning of the urgent threats posed at Installation 05, declaring codes BANDERSNATCH and HYDRA. Furthermore she recommended to UNSC Fleet Command that Delta Halo be subject to a NOVA bombing to ensure containment of the Flood.

After the initial bout of fighting around High Charity stabilised, the Sangheili fleets in orbit attempted to enforce a strict quarantine of both High Charity and Installation 05, though some ships (such as the San'Shyuum flotilla) were able to run the blockade. The blockade eventually tightened enough to prevent further infection from spreading to the rest of the galaxy for the next two weeks, in which time the Flood turned High Charity into a gargantuan Flood hive and the Sangheili fleets glassed Installation 05's surface to cauterise the outbreak on the ground. This lasted until November 17, when the battlecruiser Indulgence of Conviction was able to breach the quarantine and crash-land in the town of Voi on Earth. This infection risked accelerating to consume the entire galaxy, though was ultimately stopped in the battle of Installation 00 at the war's end.

To contain the outbreak for good the installation was glassed by the Sangheili fleets in orbit. The ring currently remains under quarantine, under observation by the UNSC's Lisbon Station.

List of appearances

• Halo 2 (First appearance)
• Halo: Ghosts of Onyx
• Halo 3
  • Cold Storage
  • Cold Storage Reports
• Halo 2: Anniversary
• Halo: Campaign Evolved
  • Terminals