Editing Battle of Installation 00

{{Era|HCW}}
{{disambig header|the final battle of the [[Human-Covenant War]]|other battles on Installation 00|Battle of Installation 00 (disambiguation)}}
{{Battle infobox
|prev=[[Battle for Earth]]
|conc=*[[Operation: MARSH FLASH]]
*[[Battle of the Citadel]]
|next=[[Raid on High Charity]]
|name=Battle of Installation 00
|image=[[File:H3 E3 Orbital Battle.jpg|440px]]
|conflict=[[Human-Covenant War]], [[Great Schism]]
|date= [[2552#December|December 11, 2552]]<ref name="Fortitude">[http://halo.xbox.com/en-us/intel/featured/video/herofortitude/bfe5038b-314a-4f17-a6be-f7613e0e3788 '''Halo Waypoint''': ''Hero-Fortitude'']</ref>
|place= [[Installation 00]] (the "Ark")
|result= '''Decisive [[United Nations Space Command|UNSC]]/[[Fleet of Retribution|Sangheili]] victory'''
*End of the [[Human-Covenant War]]
*Death of the [[Prophet of Truth]]
*All Covenant forces defeated  
*Overall collapse of the [[Covenant]]
*Truth prevented from firing the [[Halo Array]]
*Flood-infested High Charity destroyed
*Proceeded with the [[Raid on Installation 08]], leading to the destruction of [[Installation 08]], severe damage to the Ark and total defeat of the [[Flood]]
'''Minor [[Hekabe's clan]] victory'''
*Succeeded in retrieving the ''[[vertex]]'', the control device for the [[Sharquoi]]
|side1=*[[United Nations Space Command]]
*[[Covenant separatists]]
**[[Fleet of Retribution]]
*[[Sentinel|Forerunner constructs]]
|side2=*[[Covenant]]
|side3=*[[Flood]]
|commanders1=
*[[Commander|CDR]] [[Miranda Keyes]]†
*[[Shipmaster]] [[Rtas 'Vadum]]
*[[Arbiter]] [[Thel 'Vadam]]
*[[Sergeant Major|SgtMaj]] [[Avery Junior Johnson|Avery Johnson]]
*Master Chief Petty Officer [[John-117]]
*[[Cortana]]
*[[000 Tragic Solitude]]
*[[343 Guilty Spark]]
|commanders2=*[[Prophet of Truth|High Prophet of Truth]]†
*[[Cethegus]]†
*[[Hekabe]]
|commanders3=*[[Gravemind]]†
|forces1=*[[Fleet of Retribution]]/[[Seventh Fleet]]
**1 {{Class|CAS|assault carrier}}
***''[[Shadow of Intent]]''
**9 {{Class|CCS|battlecruiser}}s
***''[[Pious Inquisitor]]''
**At least 2 {{Class|Charon|light frigate}}
***{{UNSCShip|Forward Unto Dawn}}
***{{UNSCShip|Aegis Fate}}<ref group="note" name="waypoint">In Bungie's [https://halo.bungie.net/News/content.aspx?type=topnews&link=Sandtrap_Postmortem Sandtrap postmortem], a section of Sandtrap's design document reads ''"Deep within the boundless dune-fields of Waypoint, the high tech Forerunner structure encases the remnants of even older Forerunner stonework."''. During development of ''Halo 3'', "Waypoint" was the name given for the structure that would come to be known as The Ark.</ref>
**[[GA-TL1 Longsword|Longsword]] fighters
**[[D77-TC Pelican|Pelican]]s
**[[Type-52 Phantom|Phantom]]s
*Ground forces
**[[UNSC Marine Corps]]
***[[S4/BLCE/1/7]]
***[[S4/BRT/1/7]]
****[[Alpha Company, S4/BRT/1/7|Alpha Company]]
****[[Charlie Company, S4/BRT/1/7|Charlie Company]]
***[[Orbital Drop Shock Trooper]]s
****[[11th Marine Force Reconnaissance/ODST|11th MFR/ODST]]<ref name="Blind Faith"/>
**[[Sangheili]]
*Vehicles
**[[AV-14 Hornet]]s
**[[M12 Chaingun Warthog]]s
**[[M12G1 Gauss Warthog]]s
**[[M274 Mongoose]]s
**[[M808C Scorpion]]s
**[[Type-52 Phantom]]s
**Numerous [[Sentinels]]
|forces2=*[[Truth's fleet]]
**Around 30 warships<ref group="note">This is an assumption that the Sangheili Major's report on the size of Truth's fleet is accurate, bringing the total number of ships known at the time to thirty ships, exactly three times the size of the Fleet of Retribution.</ref>
***1 Forerunner [[Keyship]]
****''[[Anodyne Spirit]]''
***At least 3 {{Class|CAS|assault carrier}}s
***At least [[Foebane|one]] {{Class|ORS|heavy cruiser}}<ref name="HLC5">'''[[Halo Legendary Crate]]''' #5</ref><ref>'''[[Halo: Envoy]]'''</ref>
***Multiple {{Class|CCS|battlecruiser}}s
***At least [[Twilight Compunction|one]] [[Covenant frigate|frigate]]
**Many [[Type-31 Seraph|Seraph]] fighters
**Many [[Type-52 Phantom|Phantoms]]
*Ground forces
**[[Jiralhanae]]
**[[Kig-yar]]
**[[Unggoy]]
**[[Yanme'e]]
**[[Mgalekgolo]]
*Vehicles
**At least 3 [[Type-47B Scarab]]s
**[[Type-25 Chopper]]s
**[[Type-26 Banshee]]s
**[[Type-26 Wraith]]s
**[[Type-32 Ghost]]s
**[[Type-52 Anti-Aircraft Wraith]]s
**[[Type-52 Prowler]]s
|forces3=*[[High Charity]]
*[[Flood combat form|Combat forms]]
*[[Flood carrier form|Carrier forms]]
*[[Pod infector]]s
*[[Flood pure form|Pure forms]]
|casual1= *[[Miranda Keyes]]
*Moderate amount of Sangheili and human ships
*Numerous infantry losses
*Many Sentinels
|casual2=*[[Prophet of Truth]]
*Most ships
*Most ground forces
|casual3=*Near total
*[[High Charity]]
*[[Gravemind]]}}
{{Quote|Our fight is through the Portal, with the Brutes and the bastard Truth!|[[Shipmaster]] [[Rtas 'Vadum]]<ref>'''Halo 3''', campaign level ''[[Floodgate]]''</ref>}}
The '''Battle of Installation 00''', also known as the '''Ark Conflict''',<ref>''[[Halo: Warfleet]]'', p. 48</ref> and designated by [[United Nations Space Command]] forces as '''Operation: BLIND FAITH''',<ref name="Blind Faith">''[[Halo Encyclopedia: The Definitive Guide to the Halo Universe]]'', p.57 (2009), p.29 (2011)</ref> was a large battle between the UNSC-[[Fleet of Retribution]] alliance, the [[Covenant]], the [[Flood]], and [[Forerunner]] [[Sentinel]]s on [[2552#December|December 11, 2552]].<ref name="Fortitude"/><ref name="theark">'''Halo 3''', campaign level, ''[[The Ark (level)|The Ark]]''</ref><ref name="cov">'''Halo 3''', campaign level, ''[[The Covenant (level)|The Covenant]]''</ref><ref name="halo"/> It was the final overarching battle of the [[Human-Covenant War]] and was the last stand of the Covenant,<ref name="epi">'''Halo 3''', ''Epilogue''</ref> making it one of the few major engagements in the entire war in which the Covenant were on the defensive.

==Background==
===Battle of Installation 04===
{{Main|Battle of Installation 04}}
During the [[Battle of Installation 04]], [[Cortana]] intercepted the [[Installation]]'s [[Activation Index|Index]] as it was being inserted by [[John-117|Spartan-117]]. She continued to hold on to it after she had been removed from the Installation's [[Control Room]]. She also had spent over twelve hours inside the Control Room's computer, gaining an incredible amount of information about the [[Halo Array|Halo]] installations, making her possibly the most knowledgeable regarding the operation of the Halo rings, the Forerunners, and the Ark - perhaps even more so than [[343 Guilty Spark]], who admitted he was quite ignorant of the [[Forerunner]] structures beyond Installation 04.

===Battle of Installation 05===
{{Main|Battle of Installation 05}}
The [[Battle of Installation 05]] included many events that would become major factors in the Battle of Installation 00.

The [[United Nations Space Command|UNSC]] [[Artificial intelligence|AI]], [[Cortana]], remained aboard the [[Covenant Empire|Covenant]] holy city, [[High Charity]] as the Flood and its central consciousness, the [[Gravemind]], took control of it. From there, the Gravemind interrogated her, and she willingly answered its questions.

The aborted activation of Installation 05 had set all of the Halo rings to standby, where they could be activated from the central location of the [[Installation 00|Ark]].

Finally, the [[Covenant Empire|Covenant]] civil war, termed the [[Great Schism]], and the [[human]]-Sangheili alliance began in the space around Installation 05.

===Battle for Earth===
{{Main|Battle for Earth}}
The [[Prophet of Truth|High Prophet of Truth]] had arrived on [[Earth]] with the rest of his fleet, to complete the excavation of a [[Portal at Voi|Forerunner structure]] under the planet surface. Eventually they uncovered and activated it, opening a [[slipspace portal]] that would take them to the [[Installation 00|Ark]], a Forerunner structure from which Truth can fire all of the Halo installations at once. As he departed through the Portal, a [[Flood]]-[[Indulgence of Conviction|captured ship]] arrived on Earth and crashed. From it, John and the Arbiter were able to extract a message from [[Cortana]], alerting them that ''[[High Charity]]'' was heading for Earth and indicating that the solution to the problem of the Flood lay beyond the portal.

While [[Terrence Hood|Lord Hood]] was suspicious of [[Cortana]]'s warning and objected to going through the portal, [[Commander]] [[Miranda Keyes]], Spartan-117 and [[Shipmaster|Ship Master]] [[Rtas 'Vadum]] all indicated their wish to proceed through the Portal. Lord Hood gave Miranda Keyes command of the {{UNSCShip|Forward Unto Dawn}} for the human commitment to the mission and the fleet of ships chased after the High Prophet of Truth.

==Battle==
{{Quote|multi=yes|q1=Brute ships. Staggered line! Shipmaster, they outnumber us, three-to-one!|Sangheili Major|q2=Then it is an even fight... All cruisers, fire at will! Burn their mongrel hides!|Rtas 'Vadum|Rtas' Vadum and a Sangheili Major upon reaching the Ark<ref name="theark"/>}}

The [[Fleet of Retribution]] exited slipspace in the vicinity of the Ark on December 11, 2552, where they found the Prophet of Truth's [[Truth's fleet|fleet]] waiting for them. Despite being outnumbered three-to-one, Rtas 'Vadum declared that they were fairly matched and the Sangheili promptly engaged the enemy fleet while the ''Forward Unto Dawn'' deployed six [[D77H-TCI Pelican]]s to locate Truth. The [[Forerunner Dreadnought]] did not participate in the space battle.<ref name="theark"/> Instead, the [[Keyship]] landed amidst a Forerunner city within a region of the Ark later referred to as [[Mahsko]]. A detachment of Covenant warriors were assigned to protect the vessel as Truth left to activate the [[Halo Array]].{{Ref/Novel|Id=Sacrifice|HSoR|Detail= Adjunct - [[Sacrifice]]}}

[[File:H3 Truths fleet vs Fleet of Retribution.jpg|thumb|300px|Truth's Jiralhanae fleet confronts the Sangheili Fleet of Retribution]]

===Search for the Cartographer===
{{Main|Battle for the Cartographer (Installation 00)}}
Despite being harassed by Covenant [[Type-31 Seraph|Seraph]] fighters, five of the Pelicans deployed by the ''Forward Unto Dawn'' managed to made it to the Ark's surface. Two of the Pelicans traveled to a vast desert, where they deployed the [[John-117|Master Chief]] and four [[Orbital Drop Shock Trooper|ODSTs]] onto a cliff edge. The team made it to a ledge overlooking a group of [[Jiralhanae]], [[Unggoy]], and [[Kig-Yar]] listening to a message from Truth. Waiting for the Spartan to take the first shot with his [[SRS99D-S2 AM sniper rifle|sniper rifle]], the team proceeded to engage the clustered Covenant force. As their numbers dwindled, more Jiralhanae and several [[Type-51 Carbine|Carbine]]-wielding Kig-Yar arrived to reinforce the Covenant but ultimately the humans were successful in eliminating the Covenant soldiers. The team than proceeded through another cave which emerged into a larger area where Covenant forces were assembling an [[Type-27 Mantis|Anti-Aircraft Cannon]]. Recognizing the grave threat that the gun would be to the ''Forward Unto Dawn'', the team promptly attacked the Covenant, forcing the [[Type-52 Phantom|Phantom]] that was carrying components of the Anti-Aircraft Cannon to drop them and flee. As the team started to get an upper hand on the Covenant forces, another Phantom arrived on the battlefield, dropping a [[Mgalekgolo]] pair to engage the humans while the rest of the Covenant fell back to regroup. Despite the opposition, John-117 and the ODSTs managed to defeat the Mgalekgolo pair, before rooting out the surviving Covenant soldiers on the nearby rise. A final [[Jiralhanae Captain]] and a large group of Unggoy met the humans as they ascended the rocky pathway but they too failed to stop the team.

The team then entered a small cave, where the Chief first accessed the Forerunner [[Terminal (Halo 3)|Terminal]] network. On the other side of the cave they met a pair of [[UNSC Marine Corps|Marine]] survivors from a nearby shot down Pelican and witnessed a [[GA-TL1 Longsword]] fighter crashing. After being informed of a possible landing zone for the ''Forward Unto Dawn'', the humans ambushed the Jiralhanae and Unggoy searching the crashed Pelican. A pair of Jiralhanae [[Type-52 Prowler|Prowlers]] then entered the area, with one stopping to disgorge its occupants while the other one remained on the move, using its plasma cannon to strafe the humans. After a struggle, the team managed to kill all of the hostiles in the area. Finding that several [[M274 Mongoose|Mongooses]] had survived the Pelican crash, the humans mounted up on the vehicles. They then entered a much larger open area where the Longsword had crashed. A large Covenant force including [[Type-32 Ghost|Ghosts]] and [[Type-25 Chopper|Choppers]] occupied the area but the now-mobilized UNSC party was successful in wiping them out. Passing the crashed Longsword and a pair of [[Single Occupant Exoatmospheric Insertion Vehicle|SOEIVs]] that had landed and had the ODSTs which had once occupied them killed once they left their pods, the team arrived at a crashed Phantom, where they promptly wiped out its surviving passengers. The team than located a large [[Forerunner]] wall where a group of Covenant were being engaged by the [[Aggressor Sentinel|Sentinel]] defenders. With the assistance from the Sentinels, all of the Covenant were eliminated. [[Avery Johnson]] descended in his Pelican, informing the Master Chief that he had spotted a structure that was similar to the [[Cartographer]] of [[Installation 04]] on the other side of the wall, and Keyes set it as their objective. The ''Forward Unto Dawn'' would need to land first however, in order to deploy a vehicular force that would be sufficient to punch through the Covenant forces in front of the Cartographer building. With the Sentinels providing aerial support, the team proceeded forward, destroying a pair of Ghosts before assisting a group of Marines being attacked by more Covenant. The vehicles led by the Chief then moved to the sighted Landing Zone, which was occupied by Ghosts, a [[Type-26 Wraith|Wraith]], several [[deployable lookout tower]]s and a pair of Anti-Air Wraiths that were firing into an aerial battle between [[Type-26 Banshee|Banshees]] and [[AV-14 Hornet|Hornets]]. Despite staunch opposition, the human force was able to clear the landing zone, allowing the ''Forward Unto Dawn'' to disengage from the space battle and descend to the surface of the installation, landing safely.<ref name="theark"/>

[[File:Ark Level Scorpion.jpg|thumb|left|300px|UNSC ground forces battling in the desert.]]

From the ''Forward Unto Dawn's'' hangar, the Master Chief was reinforced with three [[M808C Scorpion|Scorpion]] tanks, a [[M12 Chaingun Warthog|Warthog]] and more [[UNSC Marine Corps|Marines]]. A Pelican arrived to transport the surviving ODSTs away while the rest of the soldiers mounted up. With [[343 Guilty Spark]] having arrived to guide them, the mechanized force then fought their way back to the Forerunner wall, destroying untold numbers of Covenant vehicles and ground troops. Arriving at the wall, which the Covenant had now reinforced with a number of Wraiths, the UNSC troops were forced to clear out all of the defenders in order to make it to the wall. The Chief, along with Guilty Spark, went through the upper, smaller doorway while the rest of the UNSC force, now reinforced with two more Warthog's, one of which was a [[M12G1 Gauss Warthog|Gauss Warthog]], went through the larger, lower doorway. The Spartan arrived at a platform overlooking a deep chasm. Here, the Monitor guided John-117 to activate the  light bridge that would allow the rest of the force to move onward. The Chief continued through the wall, emerging outside as a [[Type-47B Scarab|Scarab]] passed over him. Far below, a Covenant armored force destroyed the Warthogs that had emerged from the wall first. The Gauss Warthog, harassed by Ghosts and losing its gunner, made its way up to the Chief, where the driver offered the vehicle to the Spartan. The Chief made his way down a winding path, his gunner destroying the Ghosts and a [[Type-52 plasma cannon|plasma cannon]] before regrouping with the force of Scorpion tanks. [[Sergeant]] [[Stacker]] and the Chief led the Scorpions against a battalion-sized force of Covenant heavy armor, including Choppers, Ghosts, Wraiths and infantry with [[Type-33 fuel rod gun|heavy weapons]], reinforced by a Phantom. The Scarab than returned to the area, but even with its presence, the humans were able to clear out all of the Covenant, with John-117 personally taking down the Scarab. As the Scarab went down, [[Rtas 'Vadum]] announced that his fleet had wiped out all of the Prophet of Truth's ships; despite being outnumbered three-to-one in space, the Sangheili fleet made short work of the Covenant space forces due to the Jiralhanae being outmatched by the Sangheili in their knowledge of naval warfare,<ref name="Mythos122">'''[[Halo Mythos]]''', ''page 122''</ref> and the ''[[Shadow of Intent]]'' landed near the Cartographer.<ref name="theark"/>

[[File:H3 TanksVsScarab.png|250px|thumb|right|Scorpion Tanks battle a Scarab in the desert.]]

The Chief and his forces dismounted from their vehicles, fighting their way up a series of ramps towards the entrance to the to the Cartographer building. At the top, they met with [[Thel 'Vadam]], who dismounted from a Pelican along with a pair of Marines to accompany the Chief inside. With the help of 343 Guilty Spark, who unlocked several locked doors, the team entered a room where a number of Unggoy were sleeping. The Arbiter advised the Chief to kill them while they slept. Killing all of the Unggoy and their Jiralhanae overseer, the team continued downward, eliminating more unaware Covenant in another room before a Jiralhanae soldier gave away their position in yet another room. Despite their presence now being know, the team were able to fight through to an exterior platform where the Cartographer terminal itself was. The Chief accessed the terminal, learning that Truth had already fortified himself in a [[Installation 00 Citadel|facility]] that would allow him to remotely activate the entire Halo Array in the core of the Ark and had activated a large barrier around the entire core to ward off the attacking forces. After discovering Truth's location, a Phantom swooped in to attack. Thel 'Vadam drew its fire, allowing the Chief to escort Spark clear. Johnson announced that there was a large force of Covenant aerial support heading towards their location, and led the air battle against them while 'Vadam stole a Banshee to assist him. The Chief met with one of the Marines, who informed him that the Pelicans would land a level down from their current position. Shortly after, a group of Unggoy threw [[Type-1 plasma grenade|plasma grenades]] that killed the other Marine who was guarding the entrance to the room. The Chief and the Marine killed the Unggoy as well as a [[Jiralhanae War Chieftain|War Chieftain]] and his [[Jiralhanae Bodyguard|Bodyguards]]. They then moved downward, emerging onto the upper level of a seemingly-empty room aside from one occupant; Jiralhanae [[Jiralhanae Chieftain|Chieftain]] [[Cethegus]]. The Chieftain took a moment to taunt the Spartan, before leaving the room for the exterior platform. A group of [[Active camouflage|camouflaged]] [[Jiralhanae Stalker]]s then attacked the Chief.

Outside, Cethegus regrouped with the [[Jiralhanae Jumper|Jumpers]] from his pack, and was addressed by a hologram of the Prophet of Truth nearby. Cethegus was to defeat the Spartan in single combat, his failure to do so bringing him a fate worse than death. By this point, John-117 had slain the Stalkers and made his way out on to the platform. The Jiralhanae Jumpers moved back, allowing Cethegus to challenge the human. The ambitious Chieftain charged at John-117. After a struggle, the Master Chief was able to best Cethegus. As the Chieftain fell, the rest of his pack sprung into action, hoping to avenge their fallen commander, but they were unsuccessful and the Spartan was soon the sole survivor of the encounter. Pelican [[Kilo 023]] arrived to pick the Spartan up. After some initial uncertainty regarding a huge flock of Sentinels that were heading elsewhere on the installation, the human-Sangheili alliance decided that until the Prophet of Truth was stopped, nothing else mattered, and they left the Cartographer.<ref name="theark"/>

===Battle of the Citadel===
{{main|Battle of the Citadel}}
[[File:Trident11.jpg|thumb|left|300px|UNSC and Sangheili forces spearhead their final assault on The High Prophet of Truth.]]

The UNSC assault team, travelling in five Pelican dropships, along with a pair of Sangheili Phantoms began their attack on a trio of [[Barrier tower|towers]] that, once disabled, would drop a section of the barrier protecting the Citadel in which the Prophet of Truth was located. As the assault force closed in, they split up. Two Pelicans, including [[Kilo 023]] containing the Master Chief and a squad of [[Orbital Drop Shock Trooper|ODSTs]] would hit the first tower. The Phantoms, which carried [[Thel 'Vadam]] and his [[Sangheili]], would assault the second and the other Pelicans, ferrying Sergeant Johnson and his squad would disable the third tower. As Kilo-023 and her wingman approached the first tower, they started to take fire from an [[Type-52 Anti-Aircraft Wraith|Anti-Aircraft Wraith]] stationed on a beachhead near the tower. Kilo-023's wingman was struck in her right wing by AA fire, which rocketed her forward into Kilo-023, crushing the Warthog that was slung underneath before she spiraled into the ground. Kilo-23 was able to continue forward and landed on the beach nearby. John-117, carrying a [[M6 Spartan Laser|Spartan Laser]], led the ODSTs against a large Covenant force that was protecting the AA Wraith. Fighting their way past the crashed Pelican, the team was able to take down a [[Jiralhanae War Chieftain|War Chieftain]] and his entourage before the Master Chief neutralized the Wraith. With the beachhead secure, [[Miranda Keyes|Commander Keyes]] arrived in her Pelican to deliver a [[M12 Chaingun Warthog|Warthog]] and [[M274 Mongoose|Mongoose]] for the team to use in their assault on the tower. At the same time, the ''[[Shadow of Intent]]'' began a diversionary bombardment against the barrier, firing [[plasma torpedo]]es at the barrier shield.

The team soon arrived at the entrance to the first tower, finding it heavily defended with a [[Type-26 Wraith|Wraith]], a pair of [[Type-52 Prowler|Prowler]], numerous [[Type-32 Ghost|Ghosts]], [[Type-26 Shade|Shade]] turrets and other infantry. As the battle around the tower raged, Keyes' Pelican returned to drop [[ordnance pod]]s containing weapons for the team. Eventually clearing the area, the team proceeded inside, where they fought through more Covenant forces. Making their way to the elevator that would lead to the tower controls, John-117 went alone while the rest of the team waited behind to watch for hostiles. Before he could deactivate the tower however, the Spartan had to contend with a [[Jiralhanae]] [[pack]] lead by a [[Jiralhanae Chieftain|Chieftain]]. Eventually clearing the room, John-117 located the controls and shut the tower down. At the same time, Thel 'Vadam and his Sangheili disabled theirs. Unfortunately, Sergeant Johnson and his team ran into heavy resistance at the third tower. Johnson managed to make a final transmission warning Keyes to keep her Pelican clear because of the number of hostiles before he was cut off. Commander Keyes then ordered the Chief to meet up with Thel 'Vadam and jointly assault the third tower. The Chief returned down to the lower level, where he helped his team fight off a small group of Covenant trying to reactivate the tower. They then returned to their vehicles and made their way back to the beachhead. There, a UNSC [[Pilot#UNSC|pilot]] offered his [[AV-14 Hornet|Hornet]] to the Chief. The Spartan, with the aid of several other Hornets and Pelicans, made their way to the airspace around the second tower where the Sangheili Phantoms were under heavy attack from a large number of [[Type-26 Banshee|Banshees]] and a Covenant Phantom. The UNSC air force promptly engaged the Covenant, allowing the Sangheili to engage their Phantom's [[Active camouflage|cloaking]] systems to escape. The UNSC were able to clear the vicinity of the second tower before making their way onward to the third. The third tower was heavily defended by a pair of AA Wraiths, Shades, another standard Wraith and a huge group of Jiralhanae lead by a [[Type-33 fuel rod gun|fuel rod gun]]-wielding War Chieftain. The Chief managed to knock out the anti-air, allowing the Sangheili Phantoms to return, where they disgorged Thel 'Vadam and his men to begin a ground-side push. Ultimately, the combined assault from the air and the ground managed to collapse the Covenant defenses.

[[File:Banshee cov.jpg|thumb|right|300px|Covenant air forces engaging UNSC/Sangheili forces.]]

Landing his Hornet, the Chief, along with Thel 'Vadam and a unit of Sangheili made their way into the tower, engaging the surviving Jiralhanae from the battle outside the tower. Here they discovered the corpses of several of the [[UNSC Marine Corps|Marines]] from Johnson's group, but the Sergeant himself wasn't among them. Inside the tower, the team was confronted by a [[Mgalekgolo]] pair and a massive swarm of [[Yanme'e]] who descended from above. After a protracted battle, the team was able to wipe out the Mgalekgolo and most of the Yanme'e, the survivors retreating from the way they came. As they made their way up to the elevator, another pack of Jiralhanae as well as the surviving Yanme'e vainly tried to halt their progress but failed. Once more, the Chief proceeded to the tower controls by himself, wiping out a group of [[Jiralhanae Stalker|Stalkers]] and their War Chieftain commander. Once the Spartan activated the controls, the barrier dissipated immediately. The ''Shadow of Intent'' prepared to bombard the Citadel, but was prevented from doing so when the [[Flood]]-infested [[High Charity]] arrived, launched debris that crippled the Sangheili carrier and spread Flood across the Ark. Keyes insisted that this would only pressure Truth into activating the rings, and ordered her remaining forces to attack him directly.

During this time, the [[Jiralhanae Chieftain]] [[Hekabe]] decided to use the distraction from the Flood arrival to locate the ''[[vertex]]'' hidden on the Ark. The control device for the [[Sharquoi]], the ''vertex'' would allow Hekabe to control the creatures. Though the Prophets had some Sharquoi themselves, they had lacked the ''vertex'' and so could not control them and never unleashed them. Hekabe intended to use the ''vertex'' and the Sharquoi to gain power for himself and so fled the Ark with his loyalists before the battle ended despite fighting on the side of the Covenant.<ref name="Envoy" />

One of the pieces of debris from High Charity crashed through the window of the room John-117 was in. In moments, the Spartan was swarmed by Flood forms, with [[Pod infector]]s reanimating the fallen Jiralhanae into [[Flood combat form|combat forms]]. Fighting through the Flood, the Chief returned to the lower level where he found 'Vadam and his Sangheili engaging more Flood. Pushing through numerous Flood forces, the team made it outside where Pelicans were in the process of deploying armored vehicles for the push towards the Citadel. John-117 and [[Sergeant Stacker]] lead the assault force, which included a [[M808 Scorpion|Scorpion]] tank, a [[M12G1 Gauss Warthog|Gauss Warthog]] and a Mongoose. The assault force fought through the cliffs to the cliffside near the Citadel. Here, the Jiralhanae threw everything they had at them - Wraiths, Ghosts, Prowlers, Shade turrets and heavy weapon-wielding infantry attempted to counter the UNSC armored vehicles while Banshees and Phantoms fought against Hornets and Pelicans for superiority in the air. After a tough battle, the UNSC ground forces pushed through to a break in the cliffs that would allow them to make their way to the entrance to the Citadel. Sergeant Stacker called in more Hornets to land nearby for the Chief to use as a pair of [[Type-47B Scarab|Scarabs]] arrived in front of the Citadel as the Covenant's last line of defense. After a lengthy battle, John-117 was able to take out one of the Scarab walkers. At this point, Commander Keyes ordered all forces to focus their fire on the second Scarab. Under the sustained assault, it didn't take long for the Scarab to buckle, before John-117 finished it off. With the Scarabs down, any remaining Covenant stragglers were soon moped up by the UNSC.<ref name="cov"/>

[[File:H3 CitadelBattle.jpg|300px|left|thumb|The massive final battle of the Human-Covenant war on Truth's doorstep.]] 
A Phantom dropped Thel 'Vadam and 343 Guilty Spark in front of the Citadel, where they met up with John-117. Spark activated a light bridge and the Spartan and Sangheili entered the Citadel alone. As they made their way in, several viewscreens light up showing the Prophet of Truth giving a speech attempting to reassure his remaining followers to hold firm and also declaring that he was about the activate the [[Halo Array]]. Realizing that they had very little time left, Spartan-117 and Thel 'Vadam hastily made their way to the elevator that would carry them to Truth's level. 

[[File:Scarab explodes.jpg|thumb|right|300px|The Covenant ground forces are defeated.]]

[[Sergeant Major]] Johnson, who had disappeared during the assault on the barrier towers, had in fact been captured by Truth's forces and was being tortured into pressing the switch to activate the Array; Truth needed a [[Reclaimer]] to perform the action. Johnson attempted to goad the [[Jiralhanae Chieftain|Chieftain]] that was holding him into killing him to prevent this, but Truth realized this and stopped him. With Spartan-117 and the Arbiter too far away to stop the Prophet, Commander Keyes took her Pelican dropship and crashed it directly into the facility in an attempt to rescue Johnson. She attempted to hold off Truth's Jiralhanae [[Jiralhanae Bodyguard|Bodyguards]] with a [[M90 shotgun#M90A variant|shotgun]] and a [[M6G magnum#2552 model|magnum]], but it became apparent that she wouldn't be able to kill all of them, and Truth taunted that either her or Johnson would activate the Array. Realizing what needed to be done, she pointed her pistol at Johnson, who encouraged her to shoot him and then herself to deny Truth a means to activate the rings. Before she could however, Truth used a [[Type-25 Carbine|Spiker]] to shoot Keyes in the back, killing her. Johnson, completely stuck by grief and shock, is easily made to press the panel, starting the activation sequence for the Halo Array. At this time, John-117 and Thel 'Vadam arrived on that level, where they were confronted by a pair of Flood [[Flood tank form|tank forms]]. Instead of attacking, the [[Gravemind]] spoke to the pair through the Flood forms, offering an alliance to stop their common foe, knowing that only the Chief would be able to stop the activation sequence. Unable to see another way, the two agreed and they began a combined assault on the last bastion of Covenant soldiers protecting 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 tank forms lumbered into their midst, the huge Flood forms easily crushing the smaller Covenant soldiers. With large numbers of Pod infectors along with the efforts of the Spartan and Sangheili, the forces on the first bridge soon crumbled. On the second bridge, a pack of Jiralhanae including a unit of [[Jiralhanae Jumper|Jumpers]] fought viciously to halt the process of John-117, Vadam and the Flood, but with each Jiralhanae that fell, a new Flood combat form was produced and as a result, the Covenant forces began to collapse. Even the Chieftain and a group of fuel rod gun-wielding Unggoy [[Unggoy Heavy|Heavies]] failed to stop the determined assault. The Covenant defenders on the third and final bridge were slaughtered by the Flood before the Chief and Thel even arrived. With that, all Covenant in the Citadel had been eliminated, and the way to Truth was clear. Crossing the light bridge to the Citadel controls, the Chief and 'Vadam passed by several Flood corpses and found Johnson cradling the dead body of Commander Miranda Keyes. He urged John-117 to stop the rings. Thel 'Vadam approached Truth, who was on the floor and had already been partially infected by the Flood. Declaring his intent to have his revenge against the Prophet as the infection began to ravage Truth's body, 'Vadam allowed the Prophet to live long enough to see the Chief deactivate the Halo Array. In a final defiant declaration, Truth announced himself as the voice of the Covenant, before being fatally stabbed in the back by Thel's [[Type-1 energy sword|energy sword]]. With Truth's death, the Covenant was brought to an end.<ref name="cov"/>

[[File:TruthDeath-large.jpg|thumb|left|300px|Arbiter killing the High Prophet of Truth.]]

Almost immediately after the death of the Prophet of Truth, the Gravemind announced his sudden betrayal, his tentacles surrounding the platform. Johnson attempted to airlift John-117 and Thel away but one of the Gravemind's tentacles struck the Pelican, sending it spiraling out of control and knocking the pair to the ground near the platform. The two quickly got to their feet, standing back to back with their weapons ready as the Gravemind taunted them. Thel acknowledged that they had traded one villain for another. Suddenly, the Gravemind retracted his tentacles below the platform as a pair of combat forms clambered up to challenge the pair. Quickly slaying the combat forms, the Master Chief and Arbiter hastily made their way back towards the lift they had used to enter at Johnson's urging. As they went, myriad Flood forms attempted to stop their progress. On the second bridge, a squadron of [[Aggressor Sentinel|Sentinels]] arrived to assist the duo. With the assistance of the Forerunner constructs, John-117 and Thel soon made their way back to the lift. Discovering that the controls aren't working, they opt to use a shaft at the back of the lift. The Spartan enters first. A flickering image of [[Cortana]] leads him to a control panel. Upon activating it, [[Installation 08|an incomplete Halo ring]] rose out of the Ark's [[Foundry]]; it was suddenly clear what Cortana's "solution" to the Flood was. Realizing what needed to be done, John-117 announced his plan to fire the ring to 343 Guilty Spark. The Monitor agreed that a tactical pulse would eradicate the local Flood infestation and made his way to the ring for final preparations. The incomplete ring lacked an [[Activation Index]] however. The only way they could get another Index was to rescue Cortana from High Charity since she still possessed the Index from [[Installation 04]].<ref name="cov"/>

===Master Chief's personal quest===
{{Main|Raid on High Charity}}
Johnson picked up the Arbiter and the Chief while Guilty Spark went off to the new Installation. The party then headed to the ''Shadow of Intent'', where Johnson, 'Vadam, and Ship Master 'Vadum rounded up the UNSC and Sangheili forces. Meanwhile, Master Chief [[Raid on High Charity|infiltrated]] High Charity, successfully recovering Cortana and the Index and sabotaging the city's reactors. He escaped with the help of 'Vadam and fled onboard a crashed Pelican as the station exploded, ostensibly destroying the Gravemind.<ref>'''Halo 3''', campaign level ''[[Cortana (level)|Cortana]]''</ref>

===Finishing the fight===
{{Main|Raid on Installation 08}}
{{Quote|multi=yes|q1=We are aboard, humans...and Elites. Will you not come with us, brother?|Rtas 'Vadum|q2=No. This is our fight. And I ''will'' see it finished.|Thel 'Vadam|Thel 'Vadam wishing to finish the fight alongside John-117.<ref name="halo" />}}
With the Index secure, Thel 'Vadam ordered Rtas 'Vadum (who had safely evacuated humans and Sangheili back onboard the ''[[Shadow of Intent]]'') to escape back through the slipspace portal to Earth while he, Spartan-117, and Sergeant Major Johnson moved in on the Control Room of the incomplete Halo. The ''Forward Unto Dawn'' was left behind for them to use to escape. The Gravemind, meanwhile, had begun to rebuild itself on the new ring, and sent [[Flood dispersal pod]]s to kill the three interlopers. The Chief, 'Vadum, and Johnson, with the assistance of local [[Sentinel]]s and 343 Guilty Spark, fought through the Flood and entered the Control Room. Spark explained that the new Halo would be ready to fire within days, to which the group, particularly Johnson, protested. When Guilty Spark informed the three that activating Halo now would destroy both the Ark and the installation, Johnson told him to "deal with it" and prepared to activate the ring.<ref name="halo"/>
{{Quote|Send me out...with a bang.|[[Avery Johnson|Johnson]]'s last words<ref name="halo"/>}}

Unwilling to let "his" ring be destroyed again, 343 Guilty Spark went rampant, mortally wounded Johnson, took down the Master Chief's shields and blew the Arbiter out of the room. However, with the help of a dying Sergeant Johnson and his [[M6 Spartan Laser|Spartan Laser]], the Master Chief managed to destroy Guilty Spark and start the firing sequence of the new Halo. He and the Arbiter then took Johnson's Warthog and rushed towards the ''Forward Unto Dawn'' as the incomplete Halo powered up and started breaking apart. The two drove their way through hordes of battling Flood and [[Sentinel]] drones, with the ring world literally falling to pieces around them. The two heroes made it onto the ''Forward Unto Dawn'', where the Arbiter was almost crushed by a Scorpion tank due to the sudden acceleration of the ship. Agility and a pair of crates saved him. the Master Chief then inserted Cortana into a holotank and she activated the ''Forward Unto Dawn's ''engines. The Arbiter made his way to the bridge of the ship and took her into Slipspace just as the new Halo fired, with the Master Chief almost being crushed by the same tank which descended through the cargo hold and into space.<ref name="halo">'''Halo 3''', campaign level, ''[[Halo (Halo 3 level)|Halo]]''</ref> However, the Slipspace portal collapsed as the ''Forward Unto Dawn'' entered it, and while the forward half with the Arbiter made it to Earth, the rear half fell out of Slipspace at an unknown location, with Cortana and the Master Chief floating into the dark abyss.

The Battle of Installation 00 ended the [[Human-Covenant War]]. Months later, a monument was erected near the remains of [[Voi]] in remembrance of those who died in the line of duty, including the Master Chief's who was labeled [[Missing in action|MIA]]. The Arbiter, [[Rtas 'Vadum]] and their brethren then departed Earth for [[Sanghelios]].<ref name="epi"/>

==Aftermath==
{{Quote|For us, the storm has passed. The war is over. But let us never forget those who journeyed into the howling dark, and did not return. For their decision required courage beyond measure; sacrifice, and unshakable conviction that their fight, our fight, was elsewhere. As we start to rebuild, this hillside will remain barren. A memorial to heroes fallen. They ennobled all of us, and they shall not be forgotten.|[[Fleet Admiral]] [[Terrence Hood]] in the memorial ceremony<ref name="epi"/>}}

===Installation 00 and the Flood===
The firing of the Halo ring caused unprecedented damage to the Ark while sterilizing the installation of the Flood forces around and on it, including the Gravemind commanding the massing Flood amid the battle. Over two years later on [[2555|March 20, 2555]], during [[Operation: FAR STORM]], [[Luther Mann]] and [[N'tho 'Sraom]] arrived at the Citadel to stop the Halos from firing. Scattered around the basin were the remains of human and Covenant vehicles left over from the battle, including the empty husks of the two [[Type-47B Scarab|Scarabs]].<ref>'''[[Halo: Hunters in the Dark]]''', ''page 252''</ref>

===''Forward Unto Dawn''===
The Portal between [[Installation 00]] and Earth collapsed while {{UNSCShip|Forward Unto Dawn}} was still inside it. As a result, the ship was cut in half; the front arriving at Earth and the back half being lost in space. The Arbiter, sitting on the bridge at the time, was part of the front half but, without any engines, soon crashed into the ocean. [[John-117]] and Cortana were in the rear half, and though they survived the Portal’s collapse, they were stranded in space and declared MIA. John-117 went into cryo-sleep while Cortana activated a [[distress beacon]] indicating their status.<ref name="epi"/> After drifting in an unknown region of space for over 4 years, the rear half of the ''Dawn'' was caught in the [[gravity well]] of a Forerunner [[shield world]] known as [[Requiem]].<ref name="H4">'''[[Halo 4]]''', campaign level ''[[Requiem (level)|Requiem]]''</ref>

===Legacy===
{{Quote|no=three|1=Jerome-092|q1=Isabel, where did all this wreckage come from?|2=Isabel|q2=There was a battle here near the end of the war. The Master Chief saved us all.|3=Jerome-092|q3=It's good to know John's still out there.|4=[[Isabel]] and [[Jerome-092]] while fighting the [[Banished]] on Installation 00<ref name= "HW2">'''[[Halo Wars 2]]''', campaign level ''[[A New Enemy]]''</ref>}}
A [[Voi Memorial|monument]] was made near the town of Voi, not far from the portal structure. It read, "''In memory of those fallen in the defense of Earth and her Colonies. [[2553|March 3, 2553]].''" On it were photos of UNSC personnel who went through the portal but did not return; John-117 was honored with an etching of the number "117". With the exception of Thel 'Vadam, the Sangheili were not present at the dedication service, instead remaining aboard ''Shadow of Intent''. After the ceremony, Lord Hood, despite being unable to forgive the Sangheili for what they did to humanity at the beginning of the war, shook 'Vadam's hand and thanked him for standing beside the Master Chief at the Ark. The Arbiter then departed to ''Shadow of Intent'', and joined [[Rtas 'Vadum]] on the bridge, both agreeing to return to [[Sanghelios]] to ensure its safety. Thel 'Vadam was given command of the carrier and all Sangheili onboard departed for their homeworld.<ref name="epi"/>

In [[2555#March|March 2555]], the Ark's monitor, [[000 Tragic Solitude]], sought revenge against humanity for damaging the Ark years prior. To do so, the ancilla placed the remaining Halos on a brief countdown to activation, prompting a joint UNSC-[[Swords of Sanghelios]] [[Operation: FAR STORM|mission]] to the installation to stop the rings from firing. After Solitude's plan was thwarted, the UNSC established research facilities on the Ark.<ref name="HIND">'''Halo: Hunters in the Dark''', ''page ???''</ref> The UNSC's research team was able to repair the Ark from the damage done in the battle by directing the Ark's [[Retriever Sentinel]]s to mine lifeless systems for the needed materials for repairs.<ref>'''[[Halo Wars 2]]''' - ''[[Phoenix Logs]]'' - ''The Healing of Old Wounds''</ref>

In [[2558#September|September 2558]], the [[Jiralhanae Chieftain]] [[Hekabe]] attempted to unleash the [[Sharquoi]] on the planet [[Carrow]], having retrieved the Sharquoi control device, the ''[[vertex]]'', from the Ark during the Battle of Installation 00. Hekabe's plan was narrowly foiled by [[Gray Team]], [[Rojka 'Kasaan]] and elements of the [[Surakan Militia Volunteers]].<ref name="Envoy">'''[[Halo: Envoy]]'''</ref>

The [[Banished]] arrived on the fully repaired Ark in [[2558#November|November 2558]], killing UNSC personnel across the installation. In [[2559#March|March 2559]], the crew of the newly arrived {{UNSCShip|Spirit of Fire}} [[Second Ark Conflict|engaged]] the Banished with help from [[Isabel]], the logistics AI of [[Henry Lamb Research Facility|one of]] the UNSC research facilities.<ref name="HW2"/> Approximately six months after the initial hostilities with ''Spirit of Fire'', a force of Banished warriors lead by [[Voridus]] used a [[Banished Scarab|Scarab]] to blast a hole in the [[containment shield]] around the ruins of [[High Charity]], as they sought to scavenge materials to aid their ongoing struggle against the UNSC. However, the Banished ignored warnings about the [[Flood]] as they believed them to simply be another Covenant lie and were unaware that some of the Flood still survived in the ruined city. This inadvertently caused a Flood outbreak onto the installation, leading to a desperate struggle between the Banished and the parasite. After some time, the Banished managed to destroy a [[Proto-Gravemind]] that was moments away from becoming a Gravemind and the Ark's Sentinels and the Banished managed to once again contain the Flood.<ref>'''[[Halo Wars 2: Awakening the Nightmare]]'''</ref>

==Participants==
{{Col-begin}}
{{col-2}}
===Ships===
'''UNSC'''
*{{UNSCShip|Forward Unto Dawn}}

'''Sangheili'''
*''[[Shadow of Intent]]''
*''[[Pious Inquisitor]]''

'''Covenant'''
*''[[Twilight Compunction]]''
*''[[Foebane|Gathering of Praise]]''

===Units===
'''UNSC'''
*[[UNSC Home Fleet]]
*[[105th Shock Troops Division|105th ODST Division]]
**[[7th Shock Troops Battalion]]
*[[11th Marine Force Reconnaissance/ODST]]
*[[S4/BLCE/1/7]]
*[[S4/BRT/1/7]]
**[[Alpha Company, S4/BRT/1/7|Alpha Company]]
**[[Charlie Company, S4/BRT/1/7|Charlie Company]]

'''Allied Sangheili'''
*[[Fleet of Retribution]]

'''Covenant'''
*[[Truth's fleet]]

{{col-2}}

===Personnel===
'''UNSC'''
*[[Commander]] [[Miranda Keyes]]
*[[Master Chief Petty Officer]] [[John-117]]
*[[Cortana]]
*[[Lieutenant]] [[Hocus]]
*[[Sergeant Major]] [[Avery Junior Johnson]]
*[[Gunnery Sergeant]] [[Reynolds]]
*[[Gunnery Sergeant]] [[Stacker]]
*[[Private First Class]] [[Chips Dubbo]]

'''Fleet of Retribution'''
*[[N'tho 'Sraom]]
*[[Shipmaster]] [[Rtas 'Vadum]]
*[[Arbiter]] [[Thel 'Vadam]]
*[[Usze 'Taham]]

'''Covenant'''
*[[Prophet of Truth]]
*[[Cethegus]]
*[[Hekabe]] and his clan

'''Forerunner'''
*[[343 Guilty Spark]]
*[[Mendicant Bias]]
*[[000 Tragic Solitude]]

'''Flood'''
*[[Gravemind]]

{{col-end}}

==Gallery==
<gallery>
File:H3 SpaceBattle Concept.jpg|Concept art of the space battle above the installation.
</gallery>

==List of appearances==
*''[[Halo: First Strike]]''
**''[[Petra]]'' {{Mo}}
*''[[Halo 3]]'' {{1st}}
*''[[Halo Legends]]''
**''[[Origins]]''
*''[[Halo: Evolutions - Essential Tales of the Halo Universe]]''
**''[[From the Office of Dr. William Arthur Iqbal]]'' {{Mo}}
*''[[Halo: Broken Circle]]'' {{Im}}
*''[[Halo: Hunters in the Dark]]'' {{Mo}}
*''[[Halo Mythos]]'' {{Mo}}
*''[[Halo: Tales from Slipspace]]''
**''[[Dominion Splinter]]'' {{C|Flashback only}}
*''[[Halo Wars 2]]'' {{Mo}}
*''[[Halo: Envoy]]'' {{Mo}}
*''[[Halo: Legacy of Onyx]]'' {{Im}}
*''[[Halo: Bad Blood]]'' {{Mo}}
*''[[Halo: Shadows of Reach]]'' {{Im}}
**''[[Sacrifice]]'' {{Mo}}

==Notes==
<references group="note"/>

==Sources==
{{Ref/Sources}}

{{Engagements in the Battle of Installation 00}}
{{Human-Covenant War}}
[[Category:UNSC Victories]]
[[Category:Battle of Installation 00| ]]
[[Category:Engagements in the Battle of Installation 00| ]]