Battle of the Citadel

"Now, Prophet... your end has come."

- Fleetmaster Rtas 'Vadum as he prepares to strike the Citadel.

The Battle of the Citadel was the final battle of the Human-Covenant War and a battle within the larger Ark Conflict fought between the united forces of the United Nations Space Command and the Sangheili Fleet of Retribution as well as local Forerunner constructs against the remaining forces of the Covenant, and the Flood. The battle resulted in the death of the Prophet of Truth, the final Hierarch, and the dissolution of the Covenant empire.

Background
On November 3, 2552, the High Prophet of Truth, the final remaining Covenant Hierarch, departed from High Charity on board the Anodyne Spirit and took the bulk of remaining Covenant fleets with him, as the holy city fell to the Flood amidst the chaos of the Great Schism. Truth intended to take the Keyship, along with a very massive combined Covenant armada, to Earth, where he would be able to activate the portal beneath the city of Mombasa that had been excavated by his excavation fleet over the course of the previous two weeks. This would take him to Installation 00, where he would be able to activate the Halo Array and begin the "Great Journey". Unbeknownst to the Prophet, Spartan John-117 had managed to make it onto the keyship as it decoupled from High Charity's power grid by riding a power conduit connecting the ship to the city. After arriving in the Sol system on November 8, John-117 attempted to kill the Prophet of Truth, but failed and was forced to escape from Covenant forces. The Spartan bailed from the Keyship as it entered Earth's atmosphere on November 17, landing in the jungles of Tanzania. The Keyship would ultimately land on top of the now-uncovered portal, with the surviving Covenant warships clustering around the keyship.

Over the course of the same day, UNSC forces spearheaded by the Master Chief and Arbiter Thel 'Vadam would launch an assault on Covenant forces within the nearby city of Voi, with the objective of neutralizing Covenant anti-aircraft battery emplacements in order to allow UNSC ships to attack the Keyship. While UNSC ground forces managed to destroy the emplacements, the subsequent assault on the Keyship by Battle Group Victory of the Seventh Fleet led by the failed to destroy the Forerunner vessel. The portal then opened, and Truth fled through it with the Keyship, followed by the rest of his fleet. The UNSC would be prevented from immediately following due to the arrival of the Flood-infested battlecruiser Indulgence of Conviction. Ultimately, the Flood outbreak would be contained due to the arrival of a portion of the Sangheili Fleet of Retribution, who ended up glassing the city of Voi to prevent the parasite's spread. After a short meeting between UNSC and Sangheili leaders on board the Shadow of Intent, the battle group of Fleet of Retribution, along with a portion of the Seventh Fleet including the Dawn, entered the portal in pursuit of Truth.

Upon their arrival at Installation 00, the allied fleet, only composed of several dozens of ships, was immediately attacked by the Prophet of Truth's far larger fleet. Truth himself didn't partake in the battle, instead making his way to a facility near the Ark's core that would allow him to activate the Halo Array with the help of a "Reclaimer". Despite their overwhelming 3-to-1 numerical superiority, Fleetmaster Rtas 'Vadum confidently engaged the massive Covenant fleet with the help of the Commander Miranda Keyes, the Sangheili's superior knowledge of naval warfare tipping the battle in their favor. As the two fleets battled above the Ark, a mission to locate the Prophet of Truth was launched: Six Pelicans containing Marines and ODSTs was launched by the Forward Unto Dawn towards the surface of the installation. Five of these would survive and deploy troops into the vast desert near one of the Ark's Cartographer buildings. A force of ODSTs led by John-117 managed to clear a landing zone allowing the Dawn to deploy armor for the ground forces. Now mobilized, the UNSC advanced on the Cartographer, destroying a battalion-sized force of Covenant protecting the building, including a Scarab, before the Master Chief, Thel 'Vadam, 343 Guilty Spark and a team of Marines moved inside. Meanwhile, the Fleet of Retribution succeeded in completely destroying the Prophet of Truth's fleet save for at least one escaping heavy cruiser, with the Shadow of Intent now descending on the Ark to support UNSC ground forces on their way to the Cartographer. Fighting their way through the facility, John-117 accessed the Cartographer, ascertaining the Prophet of Truth's location and revealing that he had triggered a barrier around the Foundry to prevent a direct assault. Ultimately, the Chief left the Cartographer on board Kilo 023 after defeating Jiralhanae Chieftain Cethegus and his pack.

Battle
"Commander Keyes (COM)"

- Sergeant Major Johnson (COM)

Landing
Having secured the Cartographer and learned of the Prophet of Truth's location, the UNSC and Sangheili prepared to assault the communications array where Truth had taken refuge for the final battle. As the Citadel was protected by an energy barrier, they would need to assault several heavily-defended barrier towers in order to deactivate a small section to allow the Shadow of Intent to target the Citadel. Many Hornets were sent to engage the Banshees surrounding the area before the main force's arrival. The main force composed of five Pelicans and two Phantoms containing the assault force split into three groups. A pair of Pelicans carrying the first group, consisting of John-117 and a team of ODSTs made for the first tower, which was further inland than the others. The two Phantoms containing Thel 'Vadam and his Sangheili approached the second tower and the final three Pelicans ferried Sergeant Johnson and a large squad of Marines to the third tower. As Kilo 023 and her wingman approached the first tower, they came under bombardment from an Anti-Aircraft Wraith. Kilo 023's wingman was struck in her right wing by a fuel rod and slammed into Kilo 023, crushing the Warthog slung beneath the Pelican before plummeting to the ground. Kilo 023 managed to make it through the bombardment and landed further up the beach, depositing John-117 and his team of ODSTs. Meanwhile, high above, a massive battle erupted between Hornet VTOLs and Banshees. The Chief and his team were immediately attacked by a large force of Unggoy led by a Jiralhanae Captain while a pair of Shade turrets opened fire from further down the beach. The Spartan and ODSTs managed to clear out the Covenant infantry and John, armed with a Spartan Laser, destroyed the two Shades. They fought their way up the small hill that the Anti-Aircraft Wraith was situated on, eliminating a War Chieftain and his bodyguards before destroying the Wraith. With the beachhead secure, Commander Keyes approached in her Pelican, depositing several Marines as well as a Warthog and Mongoose for the team while Shadow of Intent began a diversionary bombardment of the citadel, launching plasma torpedoes at the energy shield.

First Tower
The team proceeded towards the first tower, destroying several Ghosts as well as a pair of Banshees that attempted to strafe them. A small Covenant position with another Shade soon fell to the UNSC assault and they proceeded up the hill towards the first tower. The team was forced to contend with heavy Covenant defenses in front of the tower's entrance, including a Wraith, multiple Ghosts, Shade turrets, a pair of Prowlers and a large group on infantry within the tower entrance itself. Once the Covenant forces outside the tower were whittled down, Miranda Keyes' Pelican returned, depositing several resupply canisters for the UNSC ground forces. After re-arming, John and the ODSTs proceeded into the tower. After clearing both floors of Covenant troops, the Spartan proceeded onto the elevator leading to the tower controls alone while the ODSTs held the lower level. Arriving on the upper level as a Jiralhanae Chieftain finished his sermon to his pack, John managed to fight his way through the Jiralhanae and deactivated the tower. At the same time, Thel 'Vadam and his forces were successful in neutralizing the second tower however Sergeant Johnson and his team had come under heavy attack from Covenant reinforcements and were becoming overwhelmed. Keyes told him she would make her way to him but he warned her off due to the heavy Covenant presence before getting cut off. Ultimately, Johnson's entire team would be killed at the third tower save for the sergeant himself, who was captured by the Covenant and taken to the citadel.

John made his way back to the lower level of the tower, assisting his team as they repelled a small group of Unggoy and Kig-Yar futilely attempting to reactivate the tower. They made their way back outside to their vehicles, and proceeded back to the beach.

Dogfights in the sky
At the beach, John took control of a Hornet in order to clear the airspace between his location and the third tower to allow several Pelicans and Sangheili Phantoms to land safely. John immediately proceeded forward towards the second tower, where the two Sangheili Phantoms were under heavy fire from a swarm of Banshees while a Covenant Phantom deployed an Anti-Aircraft Wraith on a nearby island. As the Chief along with several other Hornets engaged the Covenant forces, the separatist Phantoms engaged their cloaking systems and escaped. After clearing the airspace of the second tower, the strike force continued to the third tower, which was heavily guarded by more Banshees, two Anti-Aircraft Wraiths, a regular Wraith, Shades and a massive pack of Jiralhanae led by a War Chieftain. After a lengthy engagement, the UNSC VTOLs successfully destroyed all of the Covenant aircraft and anti-air, allowing the Phantoms to arrive and deploy Thel 'Vadam and his soldiers to assault the tower from the ground. Between the Hornets and the Sangheili ground troops, the Covenant around the third tower were wiped out. John-117 then landed his Hornet at the tower and formed up with 'Vadam.

Third Tower
As the Spartan and Sangheili pressed inward, wiping out several Jiralhanae stragglers, the Pelicans moved in to land armor and reinforcements outside the tower. In the lower level of the tower, a swarm of Yanme'e and a Mgalekgolo pair emerged to stop the assault but the group managed to bring down the gestalts and deplete the Drone's numbers, forcing the survivors to flee up the elevator shaft. Proceeding to the upper level of the tower, John and the Sangheili fought through another pack of Jiralhanae as well as the surviving Yanme'e. The Master Chief took the elevator to the upper level, meeting a plasma cannon-wielding War Chieftain and a group of Jiralhanae Stalkers. Eventually besting the cloaked Brutes and their commander, John deactivated the tower. With all three barrier towers deactivated, the shield dissipated allowing the Shadow of Intent to approach the citadel. As Rtas 'Vadum prepared to level the facility, the Covenant holy city High Charity, now heavily infested by the Flood, exited slipspace over the installation. As the former Covenant capital plummeted towards the surface of the Ark, it showered debris and Flood matter across the installation. A large chunk of this debris impacted the Shadow of Intent, crippling the assault carrier and forcing it to veer off course. Another chunk flew through the window of the third tower's upper level, delivering Flood forms into the tower. John was forced to fight his way through the parasitic creatures back to the elevator while Thel and his men were attacked by more Flood below. After reuniting with the team of Sangheili, the group made their way outside where they assisted the newly-landed UNSC reinforcements in wiping out the Flood threat. 343 Guilty Spark expressed his desire to observe the crash site of High Charity, to which Thel agreed to but refused to get any closer than the top of the nearby hills. As the two departed in a Phantom, the UNSC-Sangheili task force, now supported by heavy armor and Scorpion Tanks, began a direct offensive on the citadel.

The Final Battle
"Citadel in sight! Brutes are mobilizing everything they've got."

- A Pelican pilot informing ground forces over COMs.

As the group advanced through the nearby cave towards the citadel, lush greenery gave way to snow and ice as the group came upon a small group of Covenant commanded by a War Chieftain. After easily destroying the threat, the unit moved on, eventually emerging onto the outer rim of the massive basin that the citadel was situated in. In the airspace above the citadel, UNSC Hornets and Banshees continued to engage in heavy combat. Here, the UNSC and Sangheili were forced to deal with heavy Covenant opposition including Ghosts, Prowlers, Shade turrets and several deployable lookout towers with fuel rod gun-armed Jiralhanae. After neutralizing a final Wraith and lookout tower, Sergeant Stacker informed John-117 that several Hornets were inbound. The Spartan piloted one of the VTOLs just as a pair of Covenant s deployed in front of the citadel as a last-ditch attempt to halt their progress. A massive battle erupted as Gauss Warthogs clashed with Ghosts and Prowlers around the basin while Hornets and Pelican dropships traded fire with a unit of Banshees and the Scarabs targeted both ground and aerial UNSC forces. Eventually John-117 managed to neutralize one of the Scarabs. The destruction of one of the walkers prompted Commander Keyes to order all of her forces to focus their fire on the second Scarab. With all of the UNSC's firepower on it, it didn't take long for the second Scarab to buckle. With the loss of the two Scarabs, the Covenant lost their hold on the valley and the stragglers were mopped up in short order. With the basin now clear, Thel and 343 Guilty Spark arrived, landing on the ramp leading to the citadel's entrance. John left his vehicle and regrouped with the two. Spark activated an light bridge that allowed direct access to the citadel. With little time to waste, John, Thel and a team of Sangheili made their way into the interior of the citadel.

Truth's death and the end of the war
"Prophet of Truth"

- Thel 'Vadam

As the group made their way through the citadel's foyer towards the elevator that would take them to the upper level, John was confronted by a vision of Cortana indicating her ongoing torture by the Gravemind. Truth then sent out a message to his remaining forces: he was about to activate the Halo Array. As the group neared the elevator, Commander Keyes asked the Spartan how close he was to Truth, to which John replied that they weren't close enough to stop the Prophet in time. Meanwhile, Sergeant Johnson, who had been captured by the Covenant during the battle, was being tortured by a Jiralhanae chieftain. Johnson attempted to goad the Brute into killing him in order to deny the Prophet of a way to activate the installation but Truth knew what he was doing and ordered the chieftain to stop. As Johnson taunted the Prophet's inability to activate the Ark himself, Truth confessed that he needed the human's help. Before he could continue, Keyes flew her Pelican through the window of the room and onto the platform, crushing one of the Jiralhanae bodyguards. As the Covenant soldiers picked themselves up off the floor, Keyes emerged with a shotgun and promptly shot one of the Brutes, ordering Johnson to reveal himself. The battered sergeant told her to leave him and escape, which she refused to do, shooting an approaching Jiralhanae but only causing its energy shields to flare. Truth remarked that she wouldn't be able to kill all of them even as she pointed her shotgun and a magnum at the Brutes around her. Keyes reluctantly conceded his point, aiming her sidearm at Johnson. Knowing it was the only way to deny the Prophet a means to activate the Ark, Johnson told her to shoot him. As she hesitated, the Prophet of Truth took the opportunity to shoot her in the back with a Spiker. Commander Keyes was killed instantly, her body falling to the ground even as Johnson attempted to run to her aid before being restrained by a Jiralhanae bodyguard. Dropping the Spiker, Truth told Johnson that the Forerunners had left humanity behind because they were weak, whereas gods needed to be strong. He then took Johnson's hand and forced it onto the control panel, beginning the activation sequence of the Halo Array; Johnson, struck with grief and shock, didn't resist. As the Prophet raised his arms in victory, the elevator carrying John and his team made it to the upper level. Before they could advance, a pair of Flood tank forms dropped in front of them. Instead of attacking, the Gravemind spoke to the pair, proposing a truce to stop their common foe, as only the Master Chief could stop the activation sequence. Reluctant, but with no other choice, the group and their unlikely allies began an assault on the final bastion of Covenant soldiers guarding the Prophet of Truth.

A large group of Unggoy and Kig-Yar lead by a Jiralhanae Captain guarded the first bridge making their last stand for the Covenant Empire. The two Flood tank forms lumbered into the midst of the gathered Covenant forces, crushing the smaller soldiers with their massive arms as swarms of Pod infectors swarmed ahead. The Master Chief and Arbiter 'Vadam followed closely behind their newfound Flood allies. In the face of this determined assault, the Covenant resistance on the first bridge soon crumbled and the allies proceeded through a small room where a holographic projection of Truth cursed the Flood as a final act of treachery by the Sangheili. On the second bridge, a large pack of Jiralhanae containing a unit of Jumpers fought to stop the team and their Flood allies. It was a losing battle for the Covenant, as every Jiralhanae slain resulted in a new Flood combat form. Even the chieftain and a group of fuel rod gun-wielding Heavies failed to stop the determined assault. The Flood pressed relentlessly ahead, slaughtering the final group of Covenant defenders on the third bridge before the Human and Sangheili even arrived. A final projection of Truth defiantly claimed that even the Flood would not stop the Covenant from commencing the "Great Journey". Finally reaching the light bridge to the control platform, John and Thel proceeded across, passing several Flood corpses. As Johnson closed Miranda Keyes' eyes, he told the Chief to stop the activation sequence. Meanwhile, Thel approached the downed High Prophet of Truth, who had become partially infected by the Flood. He seized the Prophet by the neck even as the frail San'Shyuum claimed that the Sangheili had never truly believed in the promise of the Great Journey. Thel activated his energy sword as the Prophet begun to cough up Flood spores and sprout tentacles. The Arbiter angrily stated that he would have his revenge on Truth before he was consumed by the Flood. As the Gravemind taunted Truth, telling him that he would only serve as food for the Flood, Thel held the Prophet up so he could see the Master Chief deactivate the Halo Array. With his life's work destroyed, Truth gave one final defiant declaration, announcing himself as the voice of the Covenant before being fatally stabbed by Thel 'Vadam. The final Hierarch of the Covenant was dead, and what remained of the empire would crumble away soon after. As Thel gave a victorious roar and deactivate his sword, John gave him a nod of acknowledgement. The two watched as Johnson carried the lifeless corpse of Miranda Keyes into her Pelican.

Discovering the solution
As the Master Chief and Arbiter Thel 'Vadam watched Sergeant Johnson enter the Pelican, the Gravemind's tentacles suddenly erupted around the platform without warning, the Flood's central consciousness' rumbling laughter filling the chamber. Johnson quickly took control of the Pelican and took off, attempting to airlift the Spartan and Sangheili out through the broken window but the dropship was stuck by one of Gravemind's tentacles, knocking the two back onto the platform and sending the Pelican spiraling out of control. The two took up a defensive position, going back to back as the Gravemind taunted them, Thel grimly stating that they had traded one villain for another. Suddenly, the Gravemind retracted his tentacles and several combat forms climbed onto the platform to confront them.

As the two fought their way back across the bridges, now swarming with Flood forms, Johnson radioed the Spartan, telling him that he wouldn't be able to return to extract them and to make his way back to the elevator they had used to access the top level of the citadel. On the second bridge, a flock of Sentinels arrived to help the duo combat the Flood. As he passed through the small room to the first bridge, another hallucination of Cortana appeared, subtly hinting that she still possessed the Activation index for Installation 04. The pair fought their way through a myriad of Flood until they reached the elevator. Realizing that it's controls were non-funtional, they opted to use a chute in the back of the room. The Spartan dropped down first, and he immediately spotted a ghostly image of Cortana moving down a nearby hallway. Perplexed, the Chief followed, with Thel in tow. The image led them to a control panel which John activated, retracting a view screen and revealing the incomplete replacement for the destroyed Installation 04 rising out of the Ark's Foundry. Hearing 343 Guilty Spark approaching, John questioned the monitor on how long he had known about it, to which he replied that he had only learned of it at that moment. John declared his intent to activate the incomplete ring at the Ark to stop the local Flood infestation, of which Spark happily agreed with. Knowing that Cortana had the Index for the original Installation 04, and she was located in the ruined husk of High Charity, John resolved to venture into the Flood hive to retrieve her.

Aftermath
John-117 would successfully infiltrate the crashed High Charity, fighting his way through hordes of Flood until he found Cortana, who had been tortured by the Gravemind for the last thirty-eight days. Despite the torment inflicted on her, Cortana managed to hide her possession of Installation 04's Activation Index from the Gravemind. The Spartan managed to retrieve Cortana and destroy High Charity's reactors, narrowly escaping with the aid of Thel 'Vadam as the former Covenant holy city was destroyed. While Rtas 'Vadum coordinated the withdrawal of UNSC and Sangheili forces from the Ark, the Master Chief and Arbiter took a damaged Pelican from High Charity to Installation 08's control room while Sergeant Johnson landed the near the facility. Crash landing a short distance from the control room, John and Thel were forced to contend with waves of Flood arriving via dispersal pods, the Gravemind having managed to survive High Charity's destruction and attempting to rebuild itself on the installation. Fighting their way up the ramps to the top of the control room and aided by Sergeant Johnson from a nearby cliff, the group repelled waves of Flood until 343 Guilty Spark could open the doors. Inside the control center, Johnson intended to fire the unstable installation immediately. Fearing that this would destroy both the Ark as well as the newly-constructed Installation 08, 343 Guilty Spark snapped, fatally wounding Johnson with his energy beam. John was forced to battle the monitor, destroying him with several shots from Johnson's Spartan Laser. While the Sergeant succumbed to his wounds, John, with the aid of Cortana managed to activate the installation. John and Thel raced to escape as Installation 08 begun to shake itself apart. Fighting through waves of Flood and hostile Sentinel constructs, the two made it to Johnson's Warthog. The sped their way towards the parked Forward Unto Dawn as the structure of the ring collapsed around them. Narrowly making it onto the frigate, the Arbiter raced for the bridge, taking the ship into slipspace as the ring activated. Unfortunately, the Dawn was sheared in half, the forward half containing the Arbiter made it back to Earth while the rear half with the Master Chief and Cortana falling out of slipspace in an unknown location. With no other options, John entered cryo-sleep, telling Cortana to wake him if she needed him. John would not return to UNSC-controlled space until July, 2557.

Treaty of 2552
With the death of the Prophet of Truth, the Covenant finally shattered. A peace treaty between the Unified Earth Government and Thel 'Vadam's Swords of Sanghelios was ratified in February, 2553 and the Human-Covenant War was officially declared over on March 5. A ceremony presided over by Admiral Hood was held on March 5, where a monument was erected near Mount Kilimanjaro to mark the end of the war and to honor the sacrifices of everybody who gave their lives in it. Thel 'Vadam attended the ceremony, personally meeting with Lord Hood after his speech. The Admiral, while unable to forgive Thel for the actions he had committed against humanity during the war, thanked him for standing by the Master Chief at the end and expressing his sadness over the Spartan's presumed death. The Arbiter than departed for Sanghelios on board the Shadow of Intent.

Despite the dissolution of the Covenant, numerous newly formed Covenant remnants would emerge over the coming months and years, many of them still hostile to humanity. The most notable of these factions would be the group formed by Jul 'Mdama, who would continue to engage in hostilities with humanity and the Swords of Sanghelios until their defeat in October 27, 2558 Despite the Sangheili suffering from internal conflict, they would continue to wage war against the Jiralhanae until at least 2559, when the Sangheili began to gain the upper hand in the conflict as the Jiralhanae began to turn on each other. The Jiralhanae homeworld, Doisac, would be later destroyed by Cortana using her Guardians during the Created reign, scattering the Jiralhanae survivors.

Citadel
The citadel itself would remain intact, only suffering light charring and damage from the firing of Installation 08. The debris from UNSC and Covenant vehicles, including the two Scarab platforms was still present at least two years later. In March 2555, Installation 00's monitor, 000 Tragic Solitude, seeking revenge on humanity for their role in damaging the Ark, used a captured human to activate the Halo Array in order to eradicate all life in the galaxy. This countdown was discovered by Doctor Luther Mann and Henry Lamb on Installation 07. In response, a joint UNSC-Swords of Sanghelios task force was sent to the installation to stop the activation. After battling several native creatures under the control of Solitude and searching for the missing Olympia Vale, the task force regrouped at the ramp leading to the citadel's entrance. As they pondered a way to activate the now non-functional light bridge, the bridge suddenly activated by itself. After proceeding to the control panel, Doctor Mann deactivated the installation, moments before the group were attacked by two dozen Forerunner armigers. The group would ultimately survive the ambush and go on to complete their mission, rescuing Olympia Vale while 000 Tragic Solitude was destroyed by the cyborg Bobby Kodiak, who was killed in the process. With the threat of the Halo Array's activation once again neutralized, the UNSC-Sangheili task force departed from the Ark.

Ground forces

 * UNSC Navy
 * UNSC Marine Corps
 * E2-BAG/1/7
 * S4/BLCE/1/7
 * Orbital Drop Shock Troopers
 * 105th Shock Division
 * 7th Shock Troops Battalion
 * 11th MFR/ODST

Ground forces

 * Fleet of Retribution Special Warfare Group

Naval forces

 * Fleet of Retribution
 * Shadow of Intent's battle group

List of appearances

 * Halo 3
 * Halo: Evolutions
 * The Return
 * Halo: Hunters in the Dark
 * Halo Mythos: A Guide to the Story of Halo