Battle of Voi

"Marines, the Prophet of Truth doesn't know it yet, but he's about to get kicked right off his throne. You will take our city back. And drive our enemy into the grave they've been so happily digging. One final effort is all that remains."

- Fleet Admiral Terrence Hood

The Battle of Voi, also called the Siege at Voi / Siege of Voi and the Third Battle of New Mombasa, was an engagement between the UNSC-Sangheili alliance and the Covenant, and later the Flood within the town of Voi, Kenya on November 17, 2552. It was the last engagement in the Battle of Kenya at the close of the Covenant's invasion of Earth.

Background
Following the Prophet of Regrets botched attack on Earth on October 20, 2552, a large Jiralhanae-controlled fleet sent by the Prophet of Truth arrived to take control of the battle on Mombasa shortly after Regret performed a slipspace jump over the city of New Mombasa, Kenya. This fleet immediately began to glass the city of Mombasa, in order to excavate the long-buried portal that would lead the Covenant to the Ark, allowing them to fire the entire Halo Array and commence their "Great Journey". Over the next month, fighting would spread across the planet, as Covenant warships continued to arrive, attacking targets such as North America, Australia and the Antarctic, as well as the Yucatán and Cuba. . Despite the widespread combat across the globe, the Covenant under command of the Prophet of Truth and his Jiralhanae loyalists continued to focus most of their attention in eastern Africa, deploying an array of extensive defences around the excavation site around the ruins of Mombasa and heavily occupying the surrounding region of Kenya, including the Tsavo Highway and the industrial city of Voi. The final remaining UNSC stronghold in the region by mid-November was the 20th century airbase Crow's Nest. During the latter days of the Battle of Kenya, the base would house large numbers of Marine wounded during the ongoing conflict.

During the onset of the Great Schism on November 3, 2552, Chieftain of the Jiralhanae Tartarus would attempt to activate Installation 05 using the captured Commander Miranda Keyes. Ultimately he would be stopped by the combined forces of Arbiter Thel 'Vadamee and Sergeant Major Avery Johnson and the activation sequence would be averted. Despite this, Installation 05 would be moved to standby mode whereby it, along with the remaining Halo rings were primed to be activated remotely from the Ark, which lay outside the rim of the Milky Way galaxy and accessible by means of the portal on Earth. To accomplish this goal, the Prophet of Truth departed from High Charity on board the Forerunner keyship Anodyne Spirit as the Covenant holy city fell to the Flood and made a slipspace jump to the Sol system, accompanied by remaining Jiralhanae-held ships of the splintered High Charity defense fleet. Unbeknownst to the Prophet of Truth, Spartan John-117 had managed to stow away on the vessel as it decoupled from High Charity.

While Sangheili warships remained in the Coelest system to quarantine the Flood-infested Installation 05 and High Charity, Commander Keyes and Sergeant Johnson, along with Thel 'Vadam and 343 Guilty Spark, the monitor of the destroyed Installation 04 departed for Earth in pursuit of the Prophet of Truth. While Truth's arrival at Africa would be delayed as the Covenant forces on the Anodyne Spirit attempted to repel the Spartan, Keyes and her forces would arrive on Earth around November 15. Keyes would quickly take command of Crow's Nest, coordinating UNSC resistance against the Covenant and devising a plan to assault the Covenant excavation site beneath the ruins of Mombasa. On November 17, the Anodyne Spirit would descend into Earth's atmosphere, ultimately coming to rest on the now-mostly excavated portal while John-117 was forced to bail out of the ship, landing in the jungles of Tanzania. The Spartan was easily located due to the efforts of UNSC forces battling in Pakistan, and several squads of Marines led by Sergeant Johnson managed to recover John-117 and bring him to Crow's Nest. While Commander Keyes and Admiral Terrence Hood managed to inform John on the plan to neutralize a Covenant anti-aircraft cannon in Voi, the Covenant soon launched an attack on Crow's Nest. Ultimately, the UNSC were able to evacuate all of their surviving personnel before John-117 destroyed the base with a bomb. After surviving the destruction of Crow's Nest, John regrouped with a number of Marines led by Gunnery Sergeant Reynolds in an underground vehicle bay. The group took several Warthogs and left the base, rallying Marines scattered across the Kenyan savanna, including the survivors of a devastated resupply convoy led by Gunnery Sergeant Stacker. After re-establishing contact with Commander Keyes and regrouping as many UNSC forces as he could, John-117 led an assault on the Tsavo Highway, which was heavily occupied by Covenant armor. After a protracted struggle, the Master Chief was able to defeat all of the Covenant forces on the highway, opening up the path to Voi. Once mobilized, and with a final motivational speech given by Admiral Hood, John and a convoy of UNSC vehicles proceeded towards the embattled city of Voi.

Beginning
"Chief, the Prophet of Truth has found the Ark. Our only chance of stopping him is a surprise aerial assault. Clear this sector of Covenant anti-air defenses. Make a hole for the Admiral’s ships. Good hunting. Keyes out."

- Commander Miranda Keyes to John-117 as he begins his mission.

After proceeding down the Tsavo Highway, the UNSC convoy arrived outside the entrance to Traxus Factory Complex 09 on the afternoon of November 17, emerging into a parking lot that had been the site of a large battle, with numerous destroyed Warthogs and Marine corpses scattered across the area. Here, most of the Marines as well as John-117 left their Troop Transports behind while several remained on their Chaingun Warthog to provide support. As the group formed up outside the closed factory entrance, the Marine's sergeant told the Spartan to take point while they provided support. The group moved through the first room in the factory, which was empty save for the corpse of a single Marine, before hearing the voice of the Prophet of Truth. After moving up onto a nearby catwalk, the team ambushed a group of Unggoy and Kig-Yar in the next room who were listening to a holographic sermon from the Prophet who revealed that he was close to activating the artifact within the excavation crater, believed by the UNSC to be the Ark but in reality was the portal that would lead to the extra-galactic installation. After clearing the room, John opened the door allowing their supporting Chaingun Warthog to advance alongside him and the Marines. After opening up a second door, the group were confronted by a large gathering of Covenant troops including several Jiralhanae along with their parked Ghosts. As the Covenant's numbers dwindled, their commanding Jiralhanae Captain attempted to make a run for one of the Ghosts but he soon fell alongside the rest of his soldiers. After securing the tunnel, the UNSC forces moved up to the next door, which led out into the first of two lake beds in which the Covenant had stationed anti-aircraft defenses.

The lake beds
"Fleet Admiral Terrence Hood"

- Commander Miranda Keyes

Due to the Traxus facility's close proximity to the crater in which the Covenant had been excavating, the water that had once existed in the nearby lakes had been evaporated by Covenant plasma. Within the dried out ruins, the Covenant had placed a series of Anti-Aircraft Wraiths to supplement the Mantis Anti-Aircraft Cannon they had stationed near the factory. These Wraiths were already using their fuel rod cannons to devastate UNSC Hornets that were engaging squadrons of Banshees in the airspace above the factory complex by the time John-117 and his assault force arrived in the first lake bed. A single Anti-Aircraft Wraith was stationed in the lake bed, protected by a unit of Ghosts. A Phantom arrived, killing a Marine operating a missile pod on the roof of the small dock office in the center of the lake bed, forcing several other Marines to retreat while it deployed a lance of troops into the office. With the Spartan's assistance, the UNSC were able to retake the office and destroy many of the Covenant vehicles in the area. The Covenant attempted to reinforce their position in the lake bed by deploying a Wraith and more Ghosts into the area but eventually John and the other UNSC forces prevailed and the Spartan was able to destroy the Anti-Aircraft Wraith. A group of Covenant infantry arrived from the next section of the facility, deploying a plasma cannon while several Banshees attempting to strafe the Master Chief were intercepted by UNSC Hornets. In the next section of the Traxus facility, a small group of Marines defending the gate with a machine gun turret were attempting to hold out against a group of Covenant forces led by a Jiralhanae War Chieftain. The Covenant had entrenched themselves in a nearby office preventing the Marines from flushing them out and forcing them to defend against repeated assaults while further down the factory, in an an adjacent tunnel, an anti-tank unit was assembling to assault the next lake bed, where the Covenant had stationed a pair of Anti-Aircraft Wraiths and more vehicles. Fortunately for the UNSC forces, John arrived along with the forces from the now-secure first lake bed. After wiping out the Covenant infantry guarding the entrance, John made his way inside. The beleaguered Marines on the machine gun encouraged the Spartan to use a nearby door to flank the Covenant in the office and drive them out into the open where they could be cut down by the machine gun. Between John-117 and the Marine heavy machine gun, the Covenant soldiers soon fell.

With the area secure, the Marines opened up the gate for the Spartan and his forces to continue. While passing through the next room, where the UNSC had been stockpiling weaponry, a Phantom appeared above, shattering the glass roof and disgorging a swarm of Yanme'e to ambush the UNSC forces. Despite the overwhelming number of the insectoid Covenant soldiers, John-117 and the Marines were able to inflict heavy losses on the swarm, forcing the Phantom to withdraw and the surviving Drones to retreat too. As John-117 moved down the tunnel towards the Marine anti-tank unit, he was confronted by a hallucinatory vision of Cortana stating that she had "defied gods and demons", hinting to her struggle with the Gravemind on High Charity. As the anti-tank unit mounted up; a force of four Mongoose ATVs with personnel wielding rocket launchers, one of the drivers offered his vehicle to the Spartan, who obliged. With this, the unit moved into the second lake bed. Within the second lake bed, the Covenant had established a heavy presence, with a pair of Anti-Aircraft Wraiths lending their weight to an on-going aerial dogfight between UNSC and Covenant fliers while multiple Ghosts and Choppers patrolled the lake bed near a large boat that was beached due to the evaporation of the lake's water. On the boardwalk at the northern side of the lake bed, a group of Marines manning missile pods fought against a small unit of Covenant infantry. The anti-tank unit made their way into the lake bed, using their vehicle's superior manoeuvrability to their advantage while their passengers used their rocket launchers to demolish both Anti-Aircraft Wraiths and their defenders. With the Wraith's dealt with, a number of Hornets descended to provide support against low-flying Banshees. The Covenant refused to give up the lake bed, sending numerous Phantoms carrying reinforcement Ghosts into the lake bed. Despite their efforts, the UNSC anti-tank unit prevailed and the lake bed was cleared of Covenant forces allowing a Pelican do arrive with another Mongoose. In a last-ditch attempt to repel the humans, the Covenant deployed a Scarab which made its way over the roof of the factory towards the lake bed. While many Marines panicked upon hearing the walker's footfalls, Sergeant Johnson ordered them to find cover as the Scarab crashed down into the lake bed. As missile pods opened up in volleys and the anti-tank unit weaved around the Scarab's legs, Johnson ordered the UNSC forces to focus their fire on the Scarab's vulnerable leg joints. With the assistance of the Marine forces in the lake bed, John was able to destroy the Covenant assault platform. The Spartan and other Marine forces quickly moved away from the Scarab as it began to shake violently, before exploding in a massive conflagration of blue-white flames.

Assault on the anti-aircraft cannon
"Commander Miranda Keyes"

- Fleet Admiral Terrence Hood With the lake bed clear of Covenant forces, Sergeant Johnson informed John that his final target was the Covenant anti-aircraft cannon on the other side of the factory. Another Pelican arrived deploying Arbiter Thel 'Vadam. Upon meeting with John, Thel vowed that he would return honor to the Covenant once more. The two made their way inward to the next section of Traxus Factory Complex 09, which had been secured by the UNSC and was been used as a first-aid station for injured Marines and civilian factory workers. As John entered the room, he was faced with another vision of Cortana proclaiming that she was his "sword and his shield", referencing the origins of the SPARTAN-II program. Through a nearby field radio, a naval officer reported that the Covenant warships were pulling back to the the Prophet of Truth's vessel as well as indicating that the artifact was nearing activation, citing extreme winds and energy cascades across the portal's surface. Commander Keyes then reported that a single Covenant warship had appeared in-system, but Admiral Hood dismissed it, telling her that they would not get another opportunity to attack the Prophet of Truth. Several Marines accompanied John and Thel as they left the first-aid station, moving through an area of corrugated plates before arriving in the warehouse section of the facility, where Marines were pinned down by Jiralhanae forces. The group moved in, eliminating the Covenant soldiers and allowing a Marine to operate the machine gun mounted on a nearby catwalk to support the UNSC advance. A pair of Marines retreated from the next area, pursued by another pack of Brutes while further back, more Jiralhanae were violently killing factory workers. As John and Thel moved forward, clearing out the Covenant soldiers, many cowering civilians armed themselves with pistols and joined the UNSC advance. As the group approached the exit to the warehouse, they witnessed a group of retreating factory workers getting blown up by assault cannon fire. A pair of Mgalekgolo charged into the warehouse to stop the humans while more Covenant infantry led by a Jiralhanae Chieftain waited outside. The Marines and civilians managed to distract the Mgalekgolo long enough for John-117 to kill the gestalts. As the group traded fire with the Covenant outside, killing several Unggoy, the Chieftain and his bodyguards fell back up the street to a larger group of Covenant soldiers and a holotank projecting an image of the Prophet of Truth. While the opposing forces clashed, the Prophet attempted to inspire his forces by claiming that they were close to victory. As the Covenant forces dwindled, the Chieftain charged the UNSC forces with his gravity hammer but ultimately fell before the humans. As the UNSC continued towards the anti-aircraft cannon, Thel briefly paused by the holotank, angrily stating that he would never again be shamed by the Prophet. The team arrived at the base of the hill on which the Covenant anti-aircraft cannon stood, witnessing it shooting down an approaching Longsword. Commander Keyes urged John-117 to destroy the cannon as Hood's battle group was quickly approaching. With that, the group pushed up the hill, wiping out Unggoy and Kig-Yar forces that tried to stop them. Cresting the hill, John and Thel did battle with the final contingent of Covenant troops defending the cannon - a Jiralhanae War Chieftain and his assortment of bodyguards. After a furious battle, the Chieftain and his forces fell to the Master Chief and Arbiter. At Johnson's insistence, the Spartan unloaded his arsenal into the exposed heat-vent on the underside of the cannon. The cannon exploded violently, the top portion of the gun toppling off the cliff. With the threat eliminated, Battle Group Victory made its final approach.

Flood on Earth
"Commander Miranda Keyes"

- Admiral Terrence Hood

John and Thel moved to the edge of the cliff as the battle group soared overhead; several squadrons of Longswords bombarding the Anodyne Spirit while s opened fire with their Magnetic Accelerator Cannons. Explosions carpeted the Forerunner keyship's surface but the vessel was undamaged. The portal began to activate, the keyship lowered into the structure as an energy beam growing in intensity focused through the ship. As the wind of the storm intensified, John and Thel were knocked backward. The portal activated, sending out a shockwave that temporarily caused John-117 to black out. The Spartan came to in time to witness the Anodyne Spirit depart through the now-opened portal, followed by the rest of his fleet. As Thel 'Vadam roared in anger, Admiral Hood asked if the Prophet had activated, to which Commander Keyes responded in the negative. As Hood gave the order for UNSC forces to regroup, the Flood-infested exited slipspace near the city of Voi. The ship flew in low over the city, trailing rancid smoke, before crashing into Traxus Factory Complex 09. As Thel pondered the possible arrival of more Covenant, John responded that it was in fact, a far more dangerous threat - the Flood. As the Flood began to rapidly spread from the Indulgence of Conviction's crash site into the surrounding city of Voi and assimilating the corpses of humans and Covenant killed during the battle, Commander Keyes, recognizing the severity of the threat, ordered John-117 to make his way to the downed CCS-class battlecruiser and overload its engines, knowing that that was their only chance to prevent the Flood from spreading across the entire planet. Admiral Hood agreed with her assessment and John, accompanied by Thel made his way back down the hill towards the Traxus facility. The recently-victorious UNSC forces scattered across Voi began to encounter the new hostiles, and with most of them having never encountered the Flood before, were easily assimilated by the parasite. John and Thel made it back to the entrance of the facility where a squad of Marines were regrouping. Suddenly, swarms of Pod infectors and combat forms descended from the rooftops, landing amidst the Marines and rapidly infecting most of them, forcing John, Thel and the survivors to turn their weapons on them. Eventually beating back the wave of Flood, Thel urged the Spartan to hurry and find the crash site, knowing that speed was imperative to stop the Flood outbreak.

With the main door to the facility sealed, the two entered through a nearby office, arriving just in time to rescue a Marine from a swarm of Pod infectors. In the warehouse, masses of Flood combat forms were attacking scattered groups of Marines led by Gunnery Sergeant Stacker. John and Thel engaged in combat with the large numbers of infested humans and Jiralhanae, eventually clearing the area and rescuing several survivors including the sergeant. In the next area, they arrived too late to save several Marines from the Flood, including one wielding a flamethrower. Despite this, the group managed to wipe out all Flood forms present and John and Thel continued on while the surviving Marines stayed behind. Due to the warehouse doors having been sealed, John and Thel were forced to make their way across a catwalk and into a room with a hole in the floor. The two dropped down into a small room containing UNSC medical supplies and John experienced another vision of Cortana, a seemingly fragmented message warning him that she couldn't tell him much, as the Gravemind was aware that she was in "the system" - this was in truth a part of the message that Cortana had sent on board the Indulgence of Conviction as the vessel departed from the Coelest system. Within the winding pathway of corrugated steel plates, a group of Flood combat forms attempted to ambush the duo, but failed and were eliminated. The former first-aid station was empty aside from a single Marine surrounded by the corpses of his comrades. The Marine, having been driven to insanity by the Flood, babbled about how he had witnessed his squad becoming infected by the Flood and how he had subsequently had to put them down. Holding a pistol to his head, the Marine reasoned that he needed to help himself too. After doing what they could for the Marine, John and Thel proceeded out onto the lake bed on which the Spartan had previously faced the Scarab, now mostly sheared away due to the crash landing of the Indulgence of Conviction.

Sangheili reinforcements arrives
"Hail, humans, and take heed. This is the carrier Shadow of Intent. Clear this sector, while we deal with the Flood."

- Fleetmaster Rtas 'Vadum as the Shadow of Intent's battle group of the Fleet of Retribution arrives at Earth.

During the ongoing Battle for Earth, the Sangheili warships still at Installation 05 had been hard at work maintaining a quarantine of the Flood-infested High Charity. While they had successfully managed to glass the infested surface of the installation and destroy the majority of Flood-controlled vessels attempting to escape the system, the CCS-class battlecruiser Indulgence of Conviction had managed to bypass the quarantine and move to slipspace, intending to spread the Flood infection to Earth. A portion of the Fleet of Retribution led by Fleetmaster Rtas 'Vadum was quick to follow and they arrived at Earth a short while after the Flood-infested vessel's arrival. Emerging from slipspace in the city of Voi's airspace, 'Vadum sent out a message to the remaining human forces in the area, telling them to vacate the city while they dealt with the Flood. The Sangheili had also learned of what they thought was the AI Cortana's presence on the Flood ship, in truth a message sent by Cortana who was still on High Charity being tortured by the Gravemind. . The Sangheili revealed this to the senior UNSC command, who didn't want to believe them at first. Seeking to recover the AI before destroying the crash site, the Fleet of Retribution disgorged a number of drop pods carrying Special Operations Sangheili to the surface. Several of these pods landed in close proximity to John-117 and Thel 'Vadam, arriving in the ruins of the lake bed and promptly engaging the Flood combat forms surrounding them. John and Thel fought their way over to the team and with the area secure, their commanding Sangheili Major addressed Thel, revealing to the Arbiter the fall of High Charity, the failure of their quarantine effort and the evolution of the Flood. Now accompanied by the team of Special Operations Sangheili, John-117 and Thel continued to push towards the Flood ship's crash site, making their way around the rim of the devastated lake bed while engaging numerous Flood forms that leaped up from below to attack them. After fighting their way around the lake bed, they re-entered the factory, engaging another large group of combat forms. Yet more Flood forms leapt down on them from the broken glass roof where John had fought the Yanme'e previously while another cluster of combat forms approached from the next office. Commander Keyes and Johnson then contacted the Spartan, revealing that Cortana was indeed on board the ship, and his priority was to recover the AI. As they reached the lake bed where the Indulgence of Conviction had crashed, the group was confronted by a pure form: a highly-mobile stalker form, upon being confronted by the team, transformed into a hulking tank form which lumbered into close-quarters combat. After a scuffle, the team managed to put the pure form down. As John, Thel and the Special Operations Sangheili fought their way across the lake bed, fighting more pure forms and combat forms, now including infected Sangheili, a Phantom deployed another team of Sangheili closer to the vessel, but they were overwhelmed by massive numbers of Flood before John could reach them. The team was forced to fight through huge numbers of Flood forms including ranged forms which nestled onto walls and rooftops and fired organic projectiles at the group. Despite fierce resistance, the team managed to fight their way up to the ship, where a rent torn into the hull represented a path into the ship. Thel 'Vadam told John that he would remain behind while the Spartan ventured inside, in order to prevent any Flood forms from entering after him. As John made his way through corridors of thick with Flood biomass and blisters, passing several Sangheili corpses as he went, he was assailed by the voice of the Gravemind. The Flood central consciousness told him in a soothing voice not to be afraid, for he offered "peace" and "salvation". Eventually reaching a ledge, John dropped down to a lower level. As he entered a larger room, he heard the Gravemind's voice again, this time being told that the Flood was infinite, and that he should join them. Regardless, John eventually arrived at a Covenant pod, in which lay a small storage device. After activating it, Cortana's avatar appeared before him. Before she could say anything more than a mention of High Charity, her avatar flickered out of existence due to the damage that the storage device had sustained. At that moment, a separatist Phantom arrived, hovering over the open chamber. From the dropship's gravity lift, 343 Guilty Spark, the monitor of the destroyed Installation 04 arrived. Due to their prior encounter, which had been openly hostile, John kept his assault rifle levelled at Spark. Without warning, the monitor fired his laser beam over John's right shoulder, burning down a Flood combat form that had appeared behind the Spartan. The monitor then proceeded to use a small repair beam to interact with the Covenant storage device. John tore him away, warning him to leave Cortana alone. When Spark attempted to interface with the unit again, John reminded him of the monitor's attempt to kill both him and Cortana. To this, Spark replied that he had only been following his assigned protocol to protect his Installation, and due to its destruction, his sole remaining purpose was to help the Spartan. Reluctantly, John allowed Spark to pick up the storage device with his beam and carry it into the Phantom's gravity lift, with John following him into the ship. As the Phantom departed Voi, the Fleet of Retribution glassed the city and the surrounding countryside, in order to eliminate the Flood presence and prevent it from spreading across the planet and effectively ending the Battle of Voi.

Aftermath
Following the battle, UNSC and Sangheili military leaders held a meeting aboard the Sangheili flagship Shadow of Intent. 343 Guilty Spark managed to repair the Covenant storage device, where it was revealed that what was initially thought to be Cortana turned out to be a message from the AI. The message warned the UNSC and Sangheili that the Gravemind itself was coming to infest Earth aboard the former Covenant holy city High Charity. The recording also informed them that beyond the Portal was a means of stopping the Flood without firing the Halo Array. The Sangheili opted to go through the Portal after Truth, but Admrial Hood wanted to stay to defend Earth, despite the Sangheili's insistence that Earth could not survive a full-scale Flood invasion. The Master Chief and Commander Keyes, however, managed to convince Hood to allow the to accompany the Fleet of Retribution through the portal to both stop Truth and find Cortana's solution to the Flood. The Admiral acquiesced and the joint UNSC/Sangheili task force departed for Installation 00 through the portal while Admiral Hood remained behind to coordinate Earth's remaining defenses.

Although the Battle of Voi resulted in the retreat of the Covenant from Africa, remaining Covenant forces had fortified themselves across the southwestern URNA. The Prophet of Truth and his fleet's departure through the Portal sent the Covenant battlenet into disarray, allowing UNSC forces to enact a major counteroffensive in Arizona, which set the stage for eliminating the Covenant presence on Earth once and for all during Operation: MARSH FLASH in early December.

The UNSC/Sangheili task force arrived at Installation 00 on December 11, where they promptly engaged the Prophet of Truth's fleet above the Ark while John-117 spearheaded an operation to locate one of the Ark's Cartographer facilities. In the ensuing battle, Truth's fleet would be completely wiped out by the Sangheili while his location was discovered by John-117. The task force would then launch an assault on the Prophet of Truth, in which the final Hierarch of the Covenant would be killed by Thel 'Vadam, resulting in the ultimate dissolution of the Covenant and ending almost thirty years of war. John would go on to recover Cortana from the remains of High Charity, which had been brought to the Ark through a portal at Mars by the Gravemind, sparing Earth from the expected Flood invasion.

At some point following the battle, but before the official cessation of hostilities on March 3, 2553, the UNSC performed biohazard containment protocols in what remained of Voi—now dubbed the "Voi Exclusion Zone"—as part of Operation: JOINT MONITOR to ensure no Flood presence was left; none was detected. After the Human-Covenant War, the UNSC concealed Voi's glassing as a surprise attack by the Covenant, although some humans outside the UNSC, such as Staffan Sentzke, knew the truth about Voi's glassing. The arrival of the Flood on Earth also made the UNSC realize the full extent of the threat posed by the parasite; the UNSC concluded that if the Covenant had not glassed Voi, Earth would have fallen in hours. After the creation of the SPARTAN-IV Program, the UNSC began to develop training simulations for the Spartans, and create technology against the Flood, in the hypothetical case of the parasite returning to threaten the galaxy.

Ground forces

 * UNSC Navy
 * UNSC Marine Corps
 * S4/BLCE/1/7
 * S4/BRT/1/7
 * Alpha Company
 * Charlie Company

Naval forces

 * Battle Group Victory

Ground forces

 * Fleet of Retribution Special Warfare Group

Naval forces

 * Fleet of Retribution
 * One battle group

Naval forces

 * Truth's fleet

List of appearances

 * Halo: First Strike
 * Petra
 * Halo 3
 * Halo Legends
 * Origins
 * Halo: Spartan Assault
 * Halo: Mortal Dictata
 * Halo Mythos