Are there flood in reach

Explore Wikis Community Central. Register Don't have an account? Edit source History Talk 0. Multiplayer Gametypes. Basic Training. Categories Gametypes Halo 4 Multiplayer Add category. The Gravemind gives each playable hero a mission and then sends them away. Master Chief leaves Cortana behind on High Charity, the Covenant capital city now infested with Flood, and follows the Prophet of Truth on his adventure to find the Ark , the installation that built the original Halo rings and can set off all the Halos simultaneously.

Halo 3 starts with Master Chief jumping from the spaceship in Halo 2 and plummeting down to Earth in nothing but his Mjolnir armor. A group of marines revive him, and the Arbiter shows up to assist. The two form an uneasy alliance in an effort to kill the Prophet of Truth before he can activate the Ark.

The Covenant find an artifact on Earth that creates a portal to the Ark, and the Flood reach Earth via a hijacked ship. A fleet of Elites shows up to forge an alliance with humans.

Chief and the Arbiter fight their way to the central Citadel and kill the Prophet of Truth with the Gravemind 's help, but not before Truth kills Miranda Keyes. The Gravemind then turns on Chief and the Arbiter, siccing an army of Flood on them. The Ark is hard at work building a new Installation 04 to replace the one Chief broke in the original Halo.

To stop the Flood, Chief and the Arbiter attempt to activate the half-built Halo. But first, Chief needs Cortana. He battles through a crashed, overrun High Charity to get his AI back in one of the worst Halo levels of all time. Master Chief goes into cryosleep until his next adventure. Cortana wakes Master Chief up four years after Halo 3. A subset of Covenant have found the Forward Unto Dawn, and they stage an attack.

Just as the fight between John and the Covenant starts to get good, the world underneath the ships, Requiem , opens up and pulls the Covenant fleet and Chief inside. Cortana and Chief attempt to find a way off the planet to return Cortana to Dr. Halsey so she can cure the rampancy. But instead, Chief and Cortana accidentally unleash the Didact, the commander of the Forerunner army. To make matters worse, the Covenant ally with the Didact and his army of Promethean soldiers, believing the Forerunner to be a god.

A vision from the Librarian informs Chief that the Didact wants to acquire a device called the Composer and use it to finally control humans. The heroes attempt to defeat the Didact, which involves Chief violating direct orders to abandon Requiem and the fight. John and the Arbiter reluctantly accepted the Gravemind's help and the two attacked the Covenant forces while the Flood assisted them.

Finally, they came to the end of the hall. Johnson was holding Miranda, even though it was too late, and told the two to kill Truth and stop the rings from firing. Thel 'Vadam managed to capture Truth while John deactivated the rings. While Truth attempted to convince the Arbiter to help him, the Gravemind managed to infect Truth, corrupting him from the inside. Thel 'Vadam thrust his energy sword into the Prophet. With the most dangerous threat out of the way, the Gravemind then betrayed the two, having his forces in the Citadel attack them.

However, Sentinels managed to subdue some of Flood, while John and Thel 'Vadam fought their way through. They escaped through a small hole at the end of the hallway. There, the two saw the newly finished Installation John and Thel 'Vadam formulated a plan, a plan that, if it worked, would mean the end of the Flood.

John needed Cortana to execute this plan, however, so he took a Banshee and flew straight to High Charity, which had crashed on the Ark. John managed to enter High Charity and fight his way through. The Gravemind was worried, but believed its Flood forms would be enough to stop the Spartan. However, John pushed ever deeper through High Charity.

The Gravemind, in an attempt to stem the Spartan's progress, started torturing John with telepathic messages, all while Cortana was contacting John, nearing rampancy.

John continued to push into High Charity, finally reaching the reactor room, where he fought through into the Sanctum of the Hierarchs.

The Gravemind then realized what John was trying to do, but it was too late. John rescued Cortana and managed to overload the reactors by destroying three connecting pylons.

As he escaped High Charity , the Gravemind started going mad. It sent Combat forms to stop the Spartan, but John fought through them all. He raced back to find Thel 'Vadam attacking Flood Pure forms.

The two quickly boarded a nearby Pelican that crashed into the tower. When Cortana appeared on the holopad, John fired the engines and Thel 'Vadam jumped in. As the Pelican took off, the Gravemind attempted to pull the Pelican back using one of its tentacles, but was burned by the jet wash.

The Pelican raced off as High Charity collapsed behind them. Nevertheless, the Gravemind managed to escape, along with numerous Flood forms. Sergeant Johnson landed the frigate as close as possible to the Control Room. Meanwhile, John's Pelican crashed into the snowy canyon, the place where the Control Room could be found.

As the four make their way to the Control Room, the Gravemind quickly sent its forces to the Control Room. Then, it contacted John once again. The Gravemind sent its forces to begin occupying the new Halo construct. However, Guilty Spark arrived shortly after. As they went up, Sergeant Johnson supported them with his Spartan Laser. Eventually, they reached the top and Guilty Spark opened the door for them. As they hurried to the Control Room, the Gravemind began talking to John again, and Cortana realized that the Gravemind was trying to rebuild its damaged form.

As the four went in, the Gravemind tried to follow them with Combat forms, but was locked out. However, the Gravemind was able to regroup when Guilty Spark went rampant following Johnson's attempt to activate the Halo ring prematurely, mortally wounding Johnson and locking the Arbiter out of the room.

Guilty Spark then did battle with John, using a powerful hard-light beam that easily drained John's shields. Johnson, still alive, shot Spark with his Spartan Laser, before handing it to John while the Monitor recovered from the unexpected attack. The Gravemind, realizing that there was very little chance of survival, attempted to stop John and Thel 'Vadam from escaping Halo.

However, the Gravemind's forces were still battling Sentinels, leaving few Combat Forms to stop the two as they took Johnson's Warthog. As they flew into the Portal, Halo activated, killing the Gravemind and wiping out most of the surviving Flood on the Ark and on Installation 08, although it is known that at least one Flood spore survived.

At least for the moment, the Flood were seemingly defeated. However, the reason that the Forerunners preserved some of the Flood for research on the Halo rings instead of destroying them all was that they knew that the Flood would return sooner or later, and it would be better to fight a researched enemy rather than a foreign one. Despite John destroying High Charity, parts of it still remained intact and remained in the Ark, where the Flood began to recuperate from their disastrous defeat on Installation 08, though the Sentinels quarantined the surrounding area to ensure they could not escape.

Due to a lack of fresh bodies, the Flood improvised with numerous new forms to make up for this weakness. The Flood had accumulated enough biomass to create an especially large Proto-Gravemind, which was nearing critical mass to become a Gravemind. Needing all the resources they could find, the Jiralhanae brothers Voridus and Pavium began scavenging near High Charity. Vordius disregarded Atriox's orders and Pavium's advice to leave High Charity alone; seeking glory and wealth, he had a Banished Scarab breach the shield dome surrounding High Charity and sent three scouts to search inside, all of whom would be infected and turned into Combat Forms.

The Flood immediately took advantage of the naive Jiralhanae's clumsiness and began overwhelming Banished bases and scavenging operations, converting all they could find to fuel the Flood war machine. This in turn also allowed the Proto-Gravemind to expand further onto the surface.

Although the two brothers fought bravely, they knew they were fighting a losing battle. Fortunately, Voridus was able to find a partially intact Forerunner facility. The Flood deployed numerous forms to stop him but failed.

Sentinels began joining the fight against the Flood. When they reached the Proto-Gravemind, the brothers were able to weaken it slightly and send Retrievers that finished it off.

Atriox, who had been informed of the situation by Pavium, arrived shortly after the Proto-Gravemind was killed. He berated the two brothers, mostly Vordius, for the catastrophe that had occurred and ordered them to clean up their mess. As Atriox looked at the remains of the Proto-Gravemind, a horde of Sentinels were seen flying overhead to remove all Flood contamination.

The Flood, a virulent species of parasite, is an anomaly to all known biology, and an anomaly to regular life. This may be explained by the fact that it is an extragalactic species, originating from a different galaxy. The species can reproduce without host bodies, though this is described as a last-ditch effort, and only performed by pure Flood forms. The only known pathway for Flood reproduction and survival is by the infestation and assimilation of other species. They do this through a form of cellular reproduction known as lysogenic replication, where the viral cells infect host cells with their own genetic code, mutating the host cells into viral forms.

The Flood assimilate almost any species possible to their cause, although the Mgalekgolo and Yanme'e are supposedly ignored as biomass; the former being too small and lacking a central nervous system and the latter having a chitinous body which would lack calcium. This is seen during the Flood's occupation of Truth and Reconciliation , as Cortana saw them amass Sangheili and Unggoy corpses in corners of one of its hangers.

It would seem that the Flood can infest any living organism, but that they prefer hosts with a large brain capacity to accelerate the formation and expansion of the Gravemind hive intelligence and the Flood intelligence as a whole. They are only as intelligent as the beings they infect; the more cunning the enemy, the more dangerous the Flood will be.

As the Flood spread and replicate, they will alter the environment to better suit their needs. This takes the form of biomass growing on any available surface, and the air being filled with spores. This appears to be part of the Flood life cycle and is done automatically, and leads to the development of a Gravemind as well as a Flood Hive.

The Flood seem to thrive in moist and humid areas, which lends itself to the fact that the Quarantine Zone is bereft of organic life, and is cold and perpetually snowy, to hinder the development of the Flood. Infection forms selectively target other species that possess sentient intelligence and are of sufficient biomass, and can infest living or lightly wounded dead bodies. Infection forms have long tendrils that pierce the skin of the host and find their way to the spinal cord. They then synchronize with the host, matching frequencies with the host's nervous system and killing them almost instantly.

From there, they take control of the host body, replacing whatever mind originally resided there with the ravenous and voracious psyche of the Flood, although certain higher-level cognitive abilities, such as combat techniques and technical knowledge which may be useful, are retained, scanned from the victim's brain after death.

Despite this lingering of certain memories, no trace of the original mind's personality remains; only a simplistic and primal urge to assimilate or destroy other species drives the organism after infection.

In isolated cases, such as when the Flood seek very specific information from an individual's mind, they utilize an alternate, undescribed method of infestation that does not kill the host immediately; this allows the Flood to "burrow" into the host's mind, eventually giving them access to the entire scope of the host's memories. This has only been specifically seen when the Flood sought information from Captain Jacob Keyes , such as the location of Earth or a starship that would free them from Installation If a greater Flood intelligence, such as a Gravemind , is activated, then it is capable of overriding the primitive instincts of all other Flood forms, taking direct control of each and every Flood organism and making them much more dangerous, a result of being guided by a sentient mind.

It is unknown what would have happened to a still-living host such as Private Jenkins when a Gravemind attempted to influence control over it, as no living hosts were ever encountered after the activation of a Gravemind.

In addition to controlling the physical movements of the host body, the Gravemind can utilize the vocal cords of combat forms made from former Jiralhanae, Humans, and Sangheili to communicate, as well as the moans they use as observed on The Covenant , where the drop pod crashes into the third shield tower.

While baseline neurological assimilation is the same regardless of host species, The Flood's infestation includes physiological mutilation, which is species-specific. Higher-level species capable of combat, such as Humans, Jiralhanae, or Sangheili, are selectively infected to become Combat Forms.

Combat Forms retain the general profile of their original species, although they are significantly mutated. Organ systems are corrupted, organ-specific functions are decentralized, and body cavities are decayed, making hitbox-selective incapacitation impossible; organ functions are decentralized, thus, decapitation does not kill a combat form. Furthermore, highly area-specific munitions, such as sniper rifle projectiles, are completely ineffective, as picking off selective areas of a combat form leads to no wide-scale physiological impediments, and the projectile will punch through the decayed flesh rapidly, exiting through the other side of the combat form without consequence.

Combat forms also generate tentacles very quickly without regard for the skeletal structure of the host, with tentacles protruding from the combat form at odd locations, typically localized to the chest axial regions, such as the neck, armpits, or torso. A single arm is oftentimes mutated to a claw like or tentacle-like structure that splits into multiple angular, hand-like structures, replacing the hand's usage, though it will still be there.

The musculature of the combat form dramatically changes as well, and the form is given prodigious arm and leg strength, allowing for heavy blows with its arm-like structures and for incredible speed and jumping height with its legs.

The Flood are also prodigious climbers, able to scamper on walls with little hindrance to the organism. Metabolic requirements, however, appear to be extreme on the organism: blood vessels become extremely prominent on the surface of the Combat Form, with thick and distinct blood-colored vessels spawning all across the creature's surface, most prominently so on the head.

There is no confirmed way to effectively prevent a Flood infection once an Infection Form infects a host, and there is no way to reverse the effects of flood infection. However, there are known medical conditions that scramble the neural frequencies of the host apparently without major negative manifestations in the host which subsequently prevents flood infection.

For example, flood infection is impossible in a host that has contracted " Boren's Syndrome ," a neurological condition caused by radiological exposure that creates electrical anomalies in the nervous system. It has been suggested that the scrambling of neural frequencies caused by Boren's Syndrome and similar conditions renders an Infection Form incapable of tapping into the host's nervous system to kill and infect him or her.

The Infection Form is therefore unable to enact any large-scale physiological mutation; however, some Flood DNA is still spliced with the host's DNA, apparently imparting the host with enhanced regenerative capabilities.

However, this is only speculation and has yet to be independently verified. Avery J. However, the Boren's Syndrome was a story invented to cover his past in the ORION Project and the side-effects of his experimental enhancements, so the validity of each as a countermeasure against Flood infection is questionable. In the novel Halo: The Flood , Cortana uses an electrical charge which she generates from John 's suit to destroy an infection form that was attempting to infect him.

While Boren's Syndrome, if left untreated, can leave the patient immune to the Flood infection, the disease will prove fatal within a couple of years. Halsey once stated that there is a one in a billion chance that research, from someone so inflicted with Boren's Syndrome in a way that they cannot be infected, could be carried on to produce a cure. Since the Flood is a parasitic life form, they depend on other organisms for survival. Thus, the only logical foolproof way to eliminate them permanently is to take away their food sources.

The Forerunners attempted this by bombing large population centers, but this was seen as one of their last resorts and as such was performed too late in the war to make much difference.

The absolute last resort was the use of the Halo installations, which effectively destroyed all life in the galaxy and starved the Flood into extinction. However, the Forerunners' plan included some measures to preserve sentient life and return them to their home planets, allowing the Flood's "food source" to persist. Unfortunately, at the same time, specimens of Flood spore cells were kept for analysis on the Halo Installations, allowing the threat of the Flood to be merely forestalled, not eradicated.

Environmental stimuli seem to have an effect on Flood metabolism. Halo installations typically artificially incorporate low temperature into environments suffering Flood outbreak and to create natural obstacles to Flood progress, regarded as Quarantine zones.

The Flood are also vulnerable to temperatures on the other end of the spectrum. Plasma weapons will burn through them, as well as Sentinel Beams , which were specially designed to counter the Flood, indicating that the Forerunners had determined energy weapons to be the best 'basic countermeasure' available to fight the Flood. It may be a side-effect of the Flood's conversion of the body into biomass, breaking down cellular integrity and increasing flammability. There was a Forerunner belief that during their final years, Prehistoric Humanity had found a cure to the Flood.

In spite of massive Forerunner efforts to recover the data, it was either lost or destroyed when, in anticipation of their inevitable defeat by the Ur-Didact's Fleet, humanity began systematically destroying their own technology.

The lost cure altered the DNA of inoculated humans in a manner that upon infection, the altered DNA would act as a corruptive catalyst when bonded with the aggressive Flood mutagen; resulting in the physiological degradation of the Flood's neural inhibitions, to the extent that when this new Flood entity arose, it would consume all biological entities - including other flood both the traditional and Human-mutated specimens , which would in turn awaken as more altered organisms, thus self-perpetuating the disease into proportions sufficient to cause genocide through mass cannibalistic attrition.

Humanity injected one third of their population with this mutagen and then placed themselves in the Flood's path, ensuring the Flood would assimilate the disease. The plan worked, and the Flood were successfully stopped. However, it was later revealed through discoveries by the Forerunner Bornstellar that there never was a cure; that it was humanity's displayed acts of how far they would be willing to go to survive that prompted the Flood's leaders to spare them. This made humanity the first and only species to pass the Precursor's cryptic 'test'.

The most basic form of Flood evolution is the infection form, unique in its distinctive spherical shape. The infection form is used to infect organisms of other species, physically adhering to their surfaces and inserting tentacles, forcibly "hacking" into its host's nervous system, completely changing its psychology to that of the Flood's, and eventually physiologically mutating it into one of the various parasitic Flood forms of whatever the victim may be.

The Sangheili combat form may use the shield in the armor of the host. The Flood responded by launching a massive attack on the Spirit of Fire's Alpha , Bravo and Charlie Platoons to avoid them returning to the ship.

Despite massive Flood resistance, forces from the Spirit of Fire were able to rescue the platoons before their firebase was overrun by the Flood. With the proto-Gravemind dead, the smart- AI Serina was able to reacquire Anders' actual signal, which led to an ocean under which a docking port leading to the interior shield world was located. During the Spirit of Fire's descent, the outer surface of the ship was infested by the Flood.

With the aid of Sentinels and "cleansing rings" controlled by the installation's AI, the Spirit of Fire crew were able to cleanse the ship and proceed into the shield world. Within, the UNSC forces discovered that the Flood had managed to infest the interior of the shield world as well, though not to as massive of a degree as the surface planet itself. While rescuing Anders, Forge had to save her from three Flood infection forms and ran into some trouble with Flood forces on his following missions, though not to the massive extent they had been seen on the exterior planet.

In order to prevent the Covenant from getting their hands on Etran Harborage's fleet of Forerunner Sojourner -class dreadnoughts , a plan was created to use the reactor from the Spirit of Fire's Shaw-Fujikawa Translight Engine to induce the shield world's artificial star to go supernova. The plan was a success and Etran Harborage was destroyed. The explosion obliterated the Flood on the planet, along with the Covenant forces and the Forerunner fleet.

On January 1, , six years after the events on the Etran Harborage , a Flood outbreak was initiated aboard the UNSC Spirit of Fire by a Pod infector that had managed to remain hidden aboard the ship.

As the Flood threatened to breach quarantine, Serina awoke Jerome who, with the aid of Professor Ellen Anders , was forced to exterminate all infected crew members, ensuring the survival of the Spirit of Fire and its remaining crew.

All traces of the Flood parasite aboard the Spirit of Fire were erased. Although the first firing of the Halo Array starved the Flood that were at large in the Milky Way Galaxy, Flood specimens were kept in stasis within installations around the galaxy, including Installation 04 and various Forerunner research facilities. This would prove to be a grave mistake, as both humanity and the Covenant stumbled upon one of the abandoned Halo rings thousands of years after the firing of the Array.

This led both groups to Installation 04, and in turn, the Flood that were kept there in stasis. After the crash of the Pillar of Autumn on the Halo ring, piloted by Captain Jacob Keyes , the surviving crewmembers dug in for what they believed would be a long and brutal guerrilla campaign against the Covenant forces on the ring. Meanwhile, the pursuing Covenant cruisers among them the Truth and Reconciliation amassed their ground forces on the surface, where they soon discovered an underground Forerunner Flood containment facility in the swamps of the ring.

Due to the secure nature of the facility, the Covenant came to use it as a fortified base of operations and as a storage area for weapons and ammunition, oblivious to its true nature and purpose. At some point, either through a malfunction in containment equipment or a blunder on the Covenant's part, the captive Flood forms within the facility's stasis chambers were released and attacked the Covenant forces inside.

The Covenant had at least a rudimentary knowledge of what the Flood were capable of, and promptly locked the facility down and evacuated all personnel who survived the incident.

Keyes and his team were unaware of these events, and proceeded to move deep into the facility, ultimately coming across one of the unopened Flood containment chambers. Believing it was a weapons cache of some sort, the team unlocked the door, and were attacked and assimilated by the Pod infectors inside. Upon being informed of Keyes' disappearance, John was deployed to Captain Keyes' last known location on the drop ship Echo , proceeding into the facility, only to find out that most of the Marines he had been assigned to rescue, including the Captain himself, had succumbed to the Flood.

In a war of losses, this was another grim revelation for humanity. Shortly after their escape from the containment facility, Flood forces took control of a nearby crashed Spirit dropship, the Brilliant Gift and crashed it aboard the Covenant agricultural support ship Infinite Succor. The Flood quickly spread throughout the ship, infecting its crew and the animals from the vessel's hunting preserve.

The Flood began building a Proto-Gravemind , intending to use the Infinite Succor to flee the Soell system and begin infecting other planets. The ship's Legate, the Minister of Etiology , locked out the Infinite Succor's primary systems while one of the crew's Unggoy managed to send out a distress call. Suspecting human involvement, particularly that of the Demon , Supreme Commander Thel 'Vadamee sent a Covenant Special Operations team led by Rtas 'Vadumee to retake the ship and eliminate the Demon if he were onboard.

Quickly uncovering the true threat, Rtas programed the ship to make a slipspace jump into the system's star which would destroy the Infinite Succor and the Flood infestation onboard.

Though Rtas succeeded, he was the only survivor. After the Flood's escape, the Covenant forces across Installation 04 were overwhelmed by the Flood's assault. While the Covenant were able to hold the line by using vehicular and air support, most of the weaker Covenant soldiers such as Unggoy and Kig-Yar succumbed easily to the Flood, and the few Sangheili who remained were outnumbered and thus infected.

The UNSC, having a much smaller presence on the installation, found out about the Flood's might a short while later, when an ODST force engaged with the Covenant near Alpha Base , was ambushed by the Flood and suffered heavy casualties. Jenkins , who was one of the Marines in the original expeditionary mission to the supposed arms cache, was infected by a weak and elderly Pod infector whose powers of infection had been dulled by centuries of hibernation, making Jenkins' transformation into a combat form incomplete.

Jenkins was still able to resist the pervasive Flood entity in his mind, and although incapable of articulate speech and with a physiologically devastated body, Jenkins was still able to betray the Flood through hand gestures during an interrogation with Major Antonio Silva , informing the UNSC Marine battalion that the Flood planned to assault the UNSC base from a series of underground catacombs underneath their current base of operations.

In response to this intelligence, the UNSC moved to secure them, and prevented the Flood from staging another attack. During these developments, the ring's Sentinels failed to effectively contain the Flood, and because of this, the Covenant and the UNSC sustained heavy losses.

The Flood occupied areas of the ring formerly held by the Covenant, although Covenant and Flood forces continued to wage war on the massive ice plains of the ring. When he was infected, the Flood sensed that he held knowledge that would be especially useful to the Flood. Keyes knew the location of Earth , the birthplace and major stronghold of the human race, a planet with tremendous possible assimilation opportunities for the Flood. Instead of becoming a combat form, he was merged with at least four other victims into a massive, engorged proto-Gravemind aboard the CCS -class battlecruiser , Truth and Reconciliation , a Covenant warship the Flood had taken over.

While he was being incorporated into the proto-Gravemind, the Flood intelligence began to dig through his mind, searching his memories for the location of Earth. Captain Keyes successfully withheld information about Earth by constantly accessing information available on his command neural interface such as his name, rank, and serial number, until John arrived.

However, his arrival was too late, for Keyes was already dead, completely consumed by the Proto-Gravemind. It was at that time that John was forced to punch a hole into Keyes' skull to obtain the Captain's CNI transponder.

The Truth and Reconciliation was a major point of contention between the Covenant Special Operations units and the Flood. The Flood had decimated most of the Covenant crew and garrison on board, leaving only isolated pockets of resistance, mostly small numbers of terrified Unggoy and a few Sangheili aboard the vessel.

However, below the Truth and Reconciliation , in a series of rocky canyons, the Covenant were much stronger in force, with large numbers of Sangheili augmented by Unggoy, Kig-yar, and Mgalekgolo , fighting off the Flood. The Covenant Council of Masters in charge of operations on Installation 04, however, were terrified by the Flood presence.

Because the CCS-class battlecruiser had been damaged in a previous space battle with the UNSC Pillar of Autumn , it had been grounded, awaiting repairs to its underbelly and plasma carrying conduits, for at least two days.

After The Flood were discovered to be aboard the battlecruiser, the Covenant military leadership sent a Special Operations strike force to the Truth and Reconciliation to commence immediate emergency repairs, prepare it for lift-off into space and neutralize The Flood.

These efforts, however, failed, with the Flood eventually retaking the vessel. Later, the remaining UNSC Marine forces on the ring staged an assault on the Flood-held Truth and Reconciliation , and managed to neutralize most Flood forms on the cruiser in a swift assault, and prepared the battlecruiser for take-off with hastily completed emergency repairs to escape from the ring and return to Earth.

However, there was tremendous risk if the Flood-infected vessel traveled to Earth, if there was even one Flood carrier form aboard, " Earth could fall, " according to UNSC AI Wellsley , because of the Flood's exponential parasitic potential. Against orders, Marine First Lieutenant Melissa McKay destroyed the warship with whatever Flood forms were still aboard, killing hundreds of UNSC personnel, including an infected Jenkins, but saving Earth and possibly billions of lives from the Flood.

The Flood were interested in seizing space-capable vessels, in the hope of spreading the infection away from Installation 04 and across other systems; they attacked the UNSC Pillar of Autumn and cruiser Truth and Reconciliation for this reason. After the UNSC cruiser's crash-landing onto the ring, and after engaging over fifteen enemy warships previously to landing, it had been taken by the Covenant, although a UNSC strike team had managed to temporarily retake the bridge.

On the third and final day of the Battle of Installation 04, however, the Covenant were able to gain control of the crashed warship while one of many Covenant patrols around the exterior of the Autumn was ambushed by the Flood and infected; upon the patrol's return to the vessel, the Covenant garrison was attacked by the infected Elite combat forms of the patrol group.

The combat forms were able to scatter before they could all be destroyed, and a steady trickle of Flood continued to enter the Pillar of Autumn through vents and openings in the hull, waging a tedious guerrilla battle against the Covenant security force on board.

On another occasion, the Flood attempted to enter through cargo containers but were foiled due to the quick thinking of the Unggoy Yayap. Eventually, a force of Sentinels came on board, overwhelming the dwindling Covenant forces as the Flood began to attack the warship in full force, in the end almost completely obliterating the Covenant presence, and severely limiting the Sentinels' numbers on board.

Despite their best efforts and enormous numbers, the Flood, Covenant, and Sentinels were unable to stop John from detonating the wrecked warship's reactors, and escaping in a Longsword interceptor.

The resulting thermonuclear detonation from the destabilized fusion reactor cores severed a portion of the ring world, ultimately destroying it and its capability to annihilate all sentient life, and simultaneously killed all remaining Flood on Installation 04, along with any other life forms that were still present on the ring.

After the destruction of Installation 04, in October , a human prison ship , the Mona Lisa , arrived in the Soell system and managed to retrieve surviving specimens of the Flood for study from the remains of Installation They began to test the parasite on both human and Covenant prisoners, unaware of its lethality. Soon, the infection broke quarantine and the ship was infested by the Flood.

The Flood absorbed the crew and prisoners, then began to build a proto-Gravemind in its engineering section. The Flood absorbed many of her marines, leaving her and a single Sangheili to fight for a single-occupant escape pod. The outbreak was most likely contained when the Red Horse destroyed the Mona Lisa using a Shiva-class nuclear missile. The Flood were also kept in a Forerunner -constructed gas mining facility suspended over Threshold , within at least one of the three arms of the station.

A small Covenant special forces strike team, led by Special Operations Commander Rtas 'Vadumee and the Arbiter Thel 'Vadamee , were dispatched by the High Prophets to silence Sesa 'Refumee , the leader of a heretic faction , who was stationed within the mine.

The heretics released the dormant Flood within the station in an attempt to halt the progress of the Spec-Ops team through the station. The heretics' plan backfired as the Flood killed and infected many of their forces while failing to stop the Arbiter and his team. The Flood broke out of the station's arm and spread to the central core of the station, where they overwhelmed the heretics stationed there.

Eventually, even the station's Sentinel forces were completely obliterated as the Flood spread to the upper levels of the station. The Flood were unable to escape the station, however, as the Arbiter managed to sever the cable attaching it to the Forerunner support structure far above, sending the gas mine plummeting to Threshold's liquid hydrogen core, destroying it.

On Installation 05, the Flood had been in a continual battle with the Sentinels after the initial firing of the Halos , years prior. Again, a secure facility was breached and a Flood form managed to escape, thus beginning the battle with Sentinels. While the infestation had been contained to a quarantine zone established outside the Installation's Library, and presumably was severely weakened due to a lack of fresh host bodies, the Flood had managed to keep a Gravemind form alive deep within the cavernous tunnels of the ring.

With the arrival of the Covenant and pursuing UNSC forces, the Flood was able to grow its forces considerably and redouble its assault on the Installation's security forces. The Flood, despite a significant vehicular and infantry presence in the Quarantine Zone surrounding the Library, were unable to deny access to the Covenant and the UNSC.

Miranda Keyes managed to slip the In Amber Clad through the Forerunner Enforcer patrols, while the Covenant launched a ground attack, led by Thel 'Vadamee and involving a small team of Spec Ops Elites, using two anti-gravity gondolas to get to the index while attempting to control the gondolas and keep it from slipping into Flood or Sentinel hands.

Later, the In Amber Clad was captured by the Flood. John , who had arrived with Keyes and Johnson , met Thel 'Vadamee in the clutches of the Gravemind , the central controlling intelligence of the Flood hive, created from the combined intellect of tens of thousands of assimilated corpses. The Gravemind attempted to convince Thel, against his own beliefs, and through the use of the captured Monitor , Penitent Tangent , and the semi-revived and consumed Prophet of Regret to not activate the ring.

Even though Thel was still unswayed, although in question of his religion, the Gravemind sent him and John to search for the Activation Index to keep the Covenant from "turning" the "key," transporting John to High Charity , and Thel to Delta Halo's Control Room.

Taking advantage of the distraction that John's presence caused, as well as the ensuing Great Schism , the Gravemind took the opportunity to deliver itself, as well as a multitude of Flood underlings, onto the UNSC In Amber Clad and then slipspace jumped the UNSC ship directly inside High Charity, whereupon it immediately crashed into the city's superstructure to deliver its infectious cargo, while a wave of Flood-controlled Pelican dropships delivered Flood forms all over the city.

The ill-equipped and distracted populace was no match for the Flood onslaught, and the Covenant Holy City was quickly overrun, with even the Prophet of Mercy falling victim to a Pod infector. The Flood soon spread to every district, and Flood spores began to infiltrate and overload the ventilation systems within High Charity; the whole city was becoming terraformed into a gigantic Flood hive.

John, having successfully stayed in front of the wave of Flood running rampant in the streets, stowed away on the Forerunner Dreadnought that was leading Truth's fleet to Earth. Cortana, who had to stay behind to detonate In Amber Clad's engines should the situation arise and Installation 05 be fired, was left in the clutches of the Gravemind, who could potentially learn all possible human knowledge from her, including the entire knowledge directly received from Forerunner systems aboard Installation At the conclusion of the Battle of Voi , with the Prophet of Truth activating the Portal and the Jiralhanae fleet escaping to the Ark , a Flood-infested Covenant cruiser appeared out of Slipspace , having penetrated the Elites' blockade of High Charity and crash landed into the city of Voi in an effort to spread the parasite.

John, with the help of the Sangheili, was able to battle through the Flood forces, including the newly encountered Flood Pure Forms to reach the crashed cruiser where he found a message from Cortana.

Upon this discovery, Guilty Spark arrived, pledging his assistance to the Reclaimers. With the Flood spreading, John boarded a Phantom while the Sangheili went on to glass the infected areas.

The remaining Sangheili forces, fulfilling their mission of removing the Flood from Earth, retreated back to the Shadow of Intent , along with Cortana's message and Guilty Spark.