Battle of Installation 00

The Battle of Installation 00 was a large battle between the UNSC-Covenant Separatist alliance, the Covenant Loyalists, the Flood, and Forerunner Sentinels. It was the final battle of the Human-Covenant war. The Battle of the Ark and the last stand of the Covenant marked one of the few major engagements in the entire war that the Covenant were on the defensive.

Battle of Installation 04
During the Battle of Installation 04, Cortana intercepted the Installation's Index as it was being inserted by John-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 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
The Battle of Installation 05 included many events that would become major factors in the Battle of Installation 00.

The UNSC AI, Cortana, remained aboard the Covenant holy city, High Charity as the Flood and its central consciousness, the Gravemind, took control of it. From there, the Gravemind forcibly interrogated her.

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 Ark.

Finally, the Covenant Civil War and the Human-Separatist alliance began in the space around Installation 05.

Battle of Earth
The High Prophet of Truth had arrived on Earth with the rest of his fleet, to complete the digging of a Forerunner structure under the planet surface. Eventually they uncovered and activated it, opening a Portal that would take them to the Ark, a Forerunner structure from which Truth can fire all of the Halo installations at once. As he departed through the Portal, a Flood captured ship arrived on Earth and crashed. From it, they 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 Fleet Admiral Lord Hood was suspicious of Cortana's warning and objected to going through the portal, Commander Miranda Keyes, Spartan-117 and Ship Master Rtas 'Vadum all indicated their wish to proceed through the Portal. Lord Hood gave Miranda Keyes command of the Forward Unto Dawn for the human commitment to the mission and the fleet of ships chased after the High Prophet of Truth.

Battle
The High Prophet of Truth, having successfully activated the artifact in Voi, left Earth through a Slipspace portal to the Ark, a Forerunner structure that can be used to fire all of the Halo installations at once. Despite Lord Hood's urging, Commander Keyes took the Forward Unto Dawn with a small fleet of Separatist s led by the Shadow of Intent and proceeded through the Slipspace portal, arriving at the Ark. The Separatists immediately engaged the Brute fleet stationed to protect the Prophet while the Dawn deployed John-117 and Orbital Drop Shock Troopers in six Pelicans to locate Truth. Despite being outnumbered three-to-one in space, the UNSC and the Separatist fleet made short work of the Loyalist space forces, likely due to the Elites remarkable "tactical adeptness". The Brute's "tactical helplessness" can be heard in a radio transmission, saying "No! Shoot the Carrier!" The Covenant Loyalist Fleet had been destroyed and the only Loyalists left alive were Truth and his forces on the Ark. Also, presumably Truth landed the Forerunner Dreadnought on the Ark although it was never seen again and was specifically said not to take part in the battle above the Ark.



Operation: BLIND FAITH
As part of an operation called Operation: BLIND FAITH, five of the Pelicans deployed by the human frigates had made it to the Ark. The Master Chief and four ODSTs were deployed, ambushing a group of Brutes, Grunts, and Jackals listening to a message from Truth. They then proceeded to ambush another group of Covenant Loyalists building an Anti-Aircraft Gun. They entered a small cave, where the Chief first accessed the Forerunner Terminal Network. On the other side of the cave they met a pair of Marine survivors from a second shot down Pelican and witnessed a Longsword fighter crashing. After being informed of a possible landing zone for the Forward Unto Dawn, the humans ambushed the Brutes and Grunts searching the crashed Pelican, then destroyed a pair of Brute Prowlers that attacked. Now with Mongooses and Prowlers, they continued past the crashed Longsword, a pair of HEVs that had landed and had the ODST's which had once occupied them killed once they left their pods, and a crashed Phantom to a battle between Covenant and Sentinels outside a Forerunner barrier. Avery J. Johnson informed 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 Dawn would need to land first however. After meeting another group of Marines being attacked, the vehicles led by the Chief then moved to the sighted Landing Zone, which was occupied by a pair of Anti-Air Wraiths. After they cleared the LZ, the Dawn disengaged from the space battle and dove onto the surface of the installation, landing safely.



From the Dawn's hangar, the Master Chief, ODSTs, and Marines were reinforced with three Scorpion tanks and a Warthog. The human force then fought their way through a large reinforcements force back to the Forerunner wall. The Chief went through the upper, smaller doorway while the armor and vehicles (reinforced with one more Warthog and a Gauss Warthog) went through the larger, lower doorway. After activating a light bridge the Spartan went through the wall, only to see a Scarab and a Loyalist armored force destroy the Warthogs. He then fought his way to the lower doorway, which then finally opened fully, letting the tanks through. Sergeant Marcus Stacker and the Chief led the Scorpions and a Warthog through two Loyalist defense lines of Choppers, Ghosts, Wraiths, and infantry with heavy weapons, reinforced by a Phantom. When the Scarab returned, the humans then proceeded to destroy it, plus the Choppers and infantry reinforcing it. By now the Elites had defeated the entire Loyalist space fleet. The Shadow of Intent, landed near the Cartographer. Rtas 'Vadum likely ordered all his remaining ships except for the Shadow of Intent to go back to Earth and wait for his return.



343 Guilty Spark, now working with the UNSC-Separatist alliance, led John-117 and the Arbiter Thel 'Vadam, plus a pair of Marines, to the Ark's Cartographer. Fighting their way through several incompetent forces that were asleep, they get back outside where they pinpoint the Prophet's location. By then Truth had already holed himself in a secure facility 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, the UNSC-Separatist troops were attacked by a large Loyalist air force. Johnson led the air battle against them, and 'Vadam stole a Banshee to help him. The Chief, with the pair of Marines, fought his way past a group of Stalker Brutes. He then dueled with a Brute Chieftain and defeated squad of Jump Pack Brutes before being picked up by Pelican Kilo 023 after the Loyalist air force was dealt with. The humans and Elites set forth to attack Truth to stop him from activating the rings.

Battle of the Citadel


The UNSC ground forces, carried in five Pelicans, along with Separatist reinforcements in a pair of green Phantoms, assaulted three emitter pylons that powered a small section of the barrier. The Master Chief and a small squad of three of ODSTs were deployed a distance from the first tower by a Pelican after hostile fire shot down a second Pelican carrying Marines and a Warthog. The crashing Pelican also took out the ODST's Warthog. Thel 'Vadam and Elites assaulted the second tower. Sergeant Johnson took four Marines and attacked the final tower. Clearing the Loyalists heavy weapons on the beach, a new Warthog and a Mongoose were deployed and taken through heavy resistance to the tower. Clearing it, the Chief learned that the Separatists had taken down the second tower, but Johnson had been ambushed by enemy reinforcements. The Chief returned to the beach, commandeered a Hornet and helped destroy Loyalist Banshees and a Phantom, securing air control for the UNSC-Separatist forces outside the barrier. Destroying the Brute defenders outside the third tower with Hornets and Pelicans, Master Chief, Thel 'Vadam, and a team of five Elites discovered the corpses of the Marine team, except for Johnson's. When the defending forces were eliminated and the barrier deactivated, the Shadow of Intent began its attack on Truth. At the same time the former Covenant city ship High Charity arrived from Slipspace and crashed on the Ark. Debris spread from the city ship heavily damaged the Shadow of Intent and helped spread a new Flood infestation on the Ark as a means to stop Truth and to be safe from the Halo activation array. Keyes insisted that this would only pressure Truth into activating the rings, and ordered the remaining forces to attack him directly.

Fighting through an infestation of the Brutes they had just killed and Johnson's Marines, the Elites and the Chief met up with Sergeant Stacker's Marines, supported by a Scorpion, a Gauss Warthog, and a Mongoose. The humans and Elites fought through the cliffs into the Citadel, where the Halos could be activated was located. The Loyalists attempted to reinforce their troops by a large amount of Phantom transports gathered from around the installation, but the UNSC air forces countered this by attacking the Phantoms and their Banshee escorts with Hornets and Pelican Gunships. The ground forces managed to destroy the remaining Loyalist armor on the mountainside. Given another Gauss Warthog and air support from a flight of Hornets and a Pelican, the Marines destroyed Banshees, Ghosts, a Prowler, plus a pair of Scarabs dropped in front of the Citadel by Brutes. After the destruction of the Scarabs, the Loyalists had lost their grip on the Citadel area. Without any heavy support, Spartan-117 and 'Vadam personally attacked the facility where Truth was to activate the Halo installations.

Sergeant Major Johnson, who had disappeared during the assault, was in fact captured by Truth's forces and was being tortured into pressing the final switch to activate the other Halos. With Spartan-117 and the Arbiter too far away to stop High Prophet of Truth, Commander Keyes grabbed a Pelican dropship and crashed into the facility to rescue Johnson, but was killed soon after by Truth himself. However, her actions delayed Truth long enough for Spartan-117 and the Arbiter to stop him. The Gravemind dispatched Flood forces to assist Spartan-117 and the Arbiter in preventing the Halos' activation and the Arbiter personally killed Truth. However, the Gravemind betrayed them and while Johnson managed to escape with Commander Keyes' body in the Pelican, Spartan-117 and the Arbiter had to fight their way outside.

343 Guilty Spark had managed to facilitate the making of a new Halo through the Ark, explaining that a tactical pulse from it would eliminate the Flood infestation. However, this new Halo lacked an Activation Index. The only way they could get another Index was to rescue Cortana from High Charity since she still possessed the Index from Installation 04.

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 (and the Arbiter in Halo 3 Co-op) headed towards High Charity via Banshee. Through a tough battle, John-117 and the Arbiter successfully entered the ruins of High Charity and recovered Cortana, using a partly-damaged Pelican to escape while High Charity was destroyed as its reactors went critical after the they blasted them.

Finishing the Fight
With the Index secure, Thel 'Vadam ordered Rtas 'Vadum (who has safely evacuated Humans and Sangheili back on board 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 Dawn was left behind for them to use to escape. By now what was left of the Gravemind had relocated to the new Halo. The three heroes with 343 Guilty Spark made it through waves of Flood to the Control Room. 343 Guilty 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.

"Send me out, with a bang."

- Johnson's last words

Unwilling to let "his" ring be destroyed again, 343 Guilty Spark went rampant, mortally wounding Johnson and attacking Spartan-117 and the Arbiter. However, with the help of a dying Sergeant Johnson and his Spartan Laser, Spartan-117 managed to destroy Guilty Spark, later revealed to have survived, and start the firing sequence of the new Halo. He and the Arbiter then took Johnson's Warthog and rushed towards the 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 world literally falling to pieces around them. The two heroes made it onto the 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. Spartan-117 then inserted Cortana into a Holotank and she activated the Dawn's engines. The Arbiter made his way to the bridge of the Dawn and took her into Slipspace just as the new Halo fired, with Master Chief almost being crushed by the same tank which descended through the cargo hold and into space. However, the Slipspace portal collapsed as the Dawn entered it and while the forward half with the Arbiter made it to Earth, the rear half fell out of Slipspace with Cortana and Spartan-117 floating into the dark abyss.

The Battle of the Ark ended the Human-Covenant war. A monument was erected near the remains of Voi in remembrance of those who died in the line of duty including Spartan-117 who is labeled MIA. The Arbiter and his brethren then departed Earth for Sanghelios.

Aftermath
"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

Installation 00 and the Flood
It is assumed that the firing of the Halo ring either severely damaged or destroyed the Ark while killing the Flood forces around Installation 00, including the Gravemind commanding the massing Flood amid the battle.

Forward Unto Dawn
The Portal between Installation 00 and Earth collapsed while 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. However, Spartan-117 and Cortana were in the rear half and were missing.

It is known that Cortana and John-117 survived the Portal's collapse. Spartan-117 went into a cryogenic-tube while Cortana sent out a signal indicating their status. It is unknown if their message was ever received or if they were rescued. The amount of time that passed in the interim is unknown, and it is also unknown if Cortana succumbed to AI Rampancy or even survived the course of the journey, as UNSC "Smart" AI minds become too interlinked and "think themselves to death" after approximately seven years of operational service. After drifting in an unknown region of space for at least 5 years (possibly longer), the rear half of the Dawn was caught in the gravity well of Requiem.

Legacy
A monument was made near the town of Voi where the Forerunner artifact had been built. It simply read "In memory of those fallen in the defense of Earth and her Colonies. March 3, 2553." On it were the pictures of the most outstanding UNSC personnel who went through the Portal but did not return. Spartan-117 was honored on it by a "117" scratched onto the monument and a Master Chief Petty Officer of the Navy badge taped on the monument.

The Sangheili overlooked the Hillside Memorial from their ships, with Thel 'Vadam being the only one of his species to attend due to fighting alongside SPARTAN-117. After the ceremony Lord Hood, who still could not forgive the Sangheili for what they did to Humanity at the beginning of the war, thanked the Arbiter personally for fighting alongside SPARTAN-117 to the end, signalling a tentative peace between the two races after their experiences at the Ark. The Arbiter then departed to the Shadow of Intent via Phantom, and joined Rtas 'Vadum on the bridge, both agreeing to return to Sanghelios to "know that it is safe". Thel 'Vadam was given command of the carrier and all Sangheili onboard departed for their homeworld.

Survivors
The number of survivors of the battle and ships that escaped the destruction of the Ark is unknown, but it is reasonable to assume that a huge number of Humans and Sangheili survived the battle.

Ships
UNSC

Covenant Separatists
 * Shadow of Intent
 * Pious Inquisitor

Units
UNSC
 * UNSC Home Fleet
 * 105th ODST Division
 * 7th ODST Battalion
 * M/LAT-16
 * S/VRC-8
 * S4/BLCE/1/7
 * S4/BRT/1/7
 * Alpha Company
 * Charlie Company

Covenant Separatists
 * Fleet of Retribution

Covenant Loyalists
 * Truth's Fleet

Personnel
UNSC
 * Lieutenant Commander Miranda Keyes
 * Master Chief Petty Officer John-117
 * Lieutenant Hocus
 * Sergeant Major Avery Junior Johnson
 * Gunnery Sergeant Reynolds
 * Gunnery Sergeant Marcus Stacker
 * Staff Sergeant Marcus Banks
 * Private First Class Chips Dubbo

Covenant Separatists
 * Shipmaster Rtas 'Vadum
 * Arbiter Thel 'Vadam

Covenant
 * Prophet of Truth