Battle of Installation 05

The Battle of Installation 05, also known as the Battle of Delta Halo, was a major engagement between the United Nations Space Command, Covenant, Sentinels, and the Flood on the Forerunner ringworld Installation 05, otherwise known as "Delta Halo".

Introduction
During the First Battle of Earth, the Prophet of Regret lead a small fleet of two Assault Carriers and thirteen CCS-class Battlecruisers on an expeditionary raid that stumbled upon Earth, the strongest UNSC stronghold planet. After substantial ground, air, and space losses, Regret fled in an Assault Carrier over New Mombasa, opening a Slipspace rift and destroying the city in a devastating Slipspace cataclysm as it initiated an emergency jump to Installation 05, although how the Covenant obtained the coordinates to Installation 05 were unknown.

However, upon Fleet Admiral Hood's order, five United Nations Space Command Defense Force warships nearby Mombasa were close enough to catch onto the Assault Carrier's rift before it terminated: three UNSC Frigates, the, , and the , one UNSC Corvette, the , and one UNSC Prowler, the , were able to enter the Slipspace field, trailing the Assault Carrier.

Their shadowing, however, was not exactingly precise. Only the frigate In Amber Clad was successfully trailed the Assault Carrier to Installation 05. The prowler Dusk arrived days later near the Covenant homeworld ship High Charity, and the Coral Sea, Paris, and Redoubtable were not anywhere near the engagement because of the imprecise physics of Slipspace.

UNSC Offensive
While Regret's assault carrier hovered over the installation, deploying Wraiths, Ghosts, Banshees, and also companies of Elites, Jackals, Drones, and Grunts by means of Phantom dropships. The Covenant ground forces fortified themselves in a series of Forerunner ruins and temple structures, even establishing Shielded Plasma Cannons for further defense.

Meanwhile, the In Amber Clad trailed behind, and after the Assault Carrier moved off, Commander Miranda Keyes, captain of the In Amber Clad, ordered a platoon of Orbital Drop Shock Trooper special forces operators and SPARTAN-117 to establish a landing zone on Installation 05 to allow Sergeant Avery J. Johnson to bring in two flights of Pelicans and further expand the UNSC presence. The frigate made a quick pass-over of a segment of the ringworld, deploying a dozen Human Entry Vehicles. Six survived it into the atmosphere of the ring, and only four personnel eventually survived - SPARTAN-117 and three "Helljumpers". However, before they could land in the small ruins, they were detected by the Covenant, and SPARTAN-117 led the commandos in eliminating Covenant plasma turrets and holding the ruins against waves of Covenant troops until a Pelican could drop off an M12 Warthog LRV and a pair of Marines.

While the immediate objective for SPARTAN-117 and his Marines were to push through the Covenant-held Forerunner ruins, the overall UNSC objective for Installation 05 was to ensure that the Covenant would not activate the ring and extinguish all sentinent life in the galaxy. To do this, the UNSC had to infiltrate the Library, retrieve the Index, and safekeep it, thereby preventing the Covenant from using the Index to fire the ring.

After SPARTAN-117 and his men pushed through two Forerunner ruins, another Pelican air-dropped Resupply Canisters and a small number of Marines, refueling the UNSC offensive as they advanced through a ravine defended by Jackal Snipers and Drones, and as they reached another temple - this one with a hologram of the Prophet of Regret, who was sermonizing in a main Forerunner temple, preparing for the activation of the ring and the sublimation event of the "Great Journey". His elimination became the primary objective for SPARTAN-117, as his death would destabilize the Covenant politically and religiously. After Cortana deciphered the hologram, SPARTAN-117 and a pair of Marines battled through a pair of Covenant-held temples before reaching an open platform. At the time, the Covenant became aware of UNSC activity, and began becoming aggressive, so Commander Keyes sent several Pelicans towards the Master Chief, which air-dropped more Resupply Canisters on the platform.

The UNSC continued attacking, proceeding from the platform to gondola which took SPARTAN-117 and his remaining Marines to a heavily-defended Forerunner underwater temple which was guarded by Hunters, Stealth Elites, and Honor Guard Elites, amongst other Covenant forces. After emerging from the submerged temple, they emerged at a hilly Forerunner ruin, where Drones, Elites, and Grunts attempted to halt the UNSC advance, and Phantoms arrived with additional Covenant reinforcements.

However, the Covenant were ultimately unsuccessful: the UNSC, after clearing out the last ruins, were able to secure an LZ for a Pelican to air-drop Resupply Canisters and a team of Marines, who would aid SPARTAN-117 in the final push towards the main temple. They took a gondola towards the temple, which was attacked by Banshee fighters and Rangers, but they were still unable to prevent SPARTAN-117 and whatever remaining Marines from docking with the heavily-guarded Main Temple, destroy the Covenant turrets guarding it, and then proceeding to enter it, where the Prophet of Regret was finishing his final sermons regarding the activation of Installation 05.

Assassination
Then, High Charity reverted from Slipspace over Installation 05, with hundreds and hundreds of warships, including those of the Second Fleet of Homogenous Clarity. From a distress signal from Regret, Special Operations Commander Rtas 'Vadumee planned to storm the temple by Phantom dropships in an urgent measure to kill SPARTAN-117 and defend the Prophet heirarch. However, the treacherous Prophet of Truth diverted the Phantoms, deliberately allowing the SPARTAN-II to kill Regret as part of his sociopolitical plans for the Covenant.

There was a large contingent of Honor Guards that defended the Prophet, but SPARTAN-117 was able to board the Prophet's levitating gravity chair and beat the Prophet to death, although during the fray, whatever remaining Marines that were left were killed. Shortly afterwards, a Covenant Assault Carrier repositioned over the main temple, and vaporized it with an Energy Projector in an attempt to kill SPARTAN-117 in an act of vengeance, but he jumped into the ocean, escaping the vaporization, although he was grasped by the tentacles of the Gravemind, a Flood overlord creature, and taken prisoner.

Introduction
"You will journey to the surface of the ring, and retrieve this Sacred Icon. With it, we shall fulfill our promise, and begin the Great Journey."

- Prophet of Truth to the Arbiter

While Regret had been murdered, with significant consequences to the Covenant, the UNSC and the Covenant both raced to reach the Library and seize the Index - the UNSC wanted to safekeep it and prevent the installation's activation, but the Covenant desired to use the "Sacred Icon" (the Covenant name of the Index) and bring it to the Control Room of the ring and activate the Halos.

Changing of the Guard
"Recommissioning the guard was a radical step, but recent events have made it abundantly clear that the Elites can no longer guarantee our safety."

- Prophet of Truth to Rtas 'Vadumee

After the death of Regret at the hands of the "Demon", Rtas 'Vadumee was furious at the Prophet of Truth for withdrawing his men, which could have saved Regret. However, Truth deliberately and wrongfully framed the Elites for their incompetence, which had led to the death of Regret. The Honor Guards of the Covenant were recomissioned, and the Brutes took over as the guardians of the Prophet heirarchs, a move that infuriated the Elites and drove an even deeper rift between the Brutes and the Elites, who had already loathed each other.

Containment Shield
"Once the shield is down, we'll head straight to the Library. I do not wish to keep the Hierarchs waiting."

- Tartarus to the Arbiter

However, before either faction could reach the Library, it was shielded by the Containment Shield - an impenetrable energy shield denying access to the Library. The shield was projected by a Forerunner power generator buried within the Sentinel Wall, a large underground Forerunner complex heavily defended by Sentinels, Sentinel Majors, and even Enforcers. Numbers of Brutes, Jackals, and Grunts had already attempted to penetrate the Sentinel Wall, with pockets scattered all over the facility, all being overwhelmed by Sentinel defenders. However, the Arbiter was air-dropped by Tartarus's Phantom at the periphery of the wall in the beginning phase of a Covenant offensive to deactivate the Containment Shield, enter the Library, and seize the Sacred Icon.

After battling through the forward half of the Sentinel Wall and moving deeper through the facility, the Arbiter was able to destroy an Enforcer, and disengage the plug locks of the generator, and then physically disengage the generator out of its "cradle", powering off the Containment Shield. While the shield had been disengaged, the path to the Library was far from clear. There was a rampant Flood infestation: the second half of the Sentinel Wall was heavily saturated with Flood, and there were icy canyons heavily entrenched by Flood battling against outnumbered Sentinel defenders that laid between the perimeter of the Containment Shield and the Library, which was accessible only by an underground gondola.

Tartarus attempted to pick up the Arbiter and head directly for the Library, but his Phantom was engaged by an Enforcer, forcing the Arbiter to battle through through the warring Flood and Sentinels that resided in the Flood-Infested Wall by himself. However, the Arbiter was not alone - the UNSC had dispatched a squad of Marines to also fight through the facility, but they were overwhelmed by the Flood, leaving a trail of crumpled bodies throughout the facility. The Covenant appearantly sent a small team of three Special Operations Elites to clear out the lower levels of the complex, but these too were killed. Finally, the Arbiter jumped down a series of plummeting vertical tunnels, exiting from the Sentinel Wall and entering the battle-torn icy plains of the Quarantine Zone.

Battle of the Quarantine Zone
"The Flood are upon us!"

- Special Operations Elite

"We must hold this campus until reinforcements arrive."

- Special Operations Commander Rtas 'Vadumee

The Quarantine Zone was supposed to be a location where during times of war, the Sentinel custodians of the installation could herd the Flood, and prevent them from entering the Library. Two Sentinel Constructor Factory ships hung in the air, deploying Sentinel reinforcements. However, the Quarantine Zone was compromised by the Flood, and the Flood managed to crash one of the floating factories, sending it plummeting down to the ringworld.

The Covenant shortly established a "camp", air-dropping seven drop pods that contained Rtas 'Vadumee and six Special Operations Elites, along with several plasma turrets and a deployable gravity lift tower.

"We shall cut into the heart of this infestation, retrieve the icon, and burn any Flood that stand in our way! Forward, warriors, and fear not pain or death. Go, Arbiter, I'll follow when our reinforcements arrive."

- Rtas 'Vadumee

The Arbiter met with three of the Elites just outside of the Sentinel Wall, and togther, they defended a small hill from the Flood before pushing inwards, where the Special Operations Commander had landed and established a small outpost, deplete with turrets and the gravity lift tower, where the Special Operations force held out against waves of Flood attacks from the cliffs before they were reinforced by a pair of Phantoms that dropped off a Spectre and a pair of Ghosts. The Covenant were able to use these vehicles to advance through a large indoor Forerunner facility before entering the first of a series of expansive outdoor arctic canyons. Despite the prowess of the Special Operations Elites and the Arbiter, the UNSC were swifter to advance through the Quarantine Zone - the In Amber Clad deployed a Pelican dropship that cruised above the battling Flood and Sentinels, cutting directly towards the Library while the Arbiter and his men were forced to fight through waves of Flood, including Flood-commandeered Ghosts, Warthogs, Wraiths, and Scorpions, while all the while, Enforcers rained heavy fire.

"Arbiter, I'm sending some of my best fighters to assist you. Do not squander their talents."

- Rtas 'Vadumee

The small Covenant taskforce was forced to debark from its vehicles as they transversed the wreckage of one of the Sentinel Constructor Factories, although just beyond the wreckage on the other side, they were met by another Covenant Phantom, this one dropping off a Spectre manned by Rtas 'Vadumee himself and another Special Operations Elite. However, as they progressed through the last series of snowy plains, they were met with increasingly heavy resistance as they neared the Library. The Sentinels were in much larger force, while a large number of Flood-infested humans savagely held a barricade against the Library, using crates, turrets, and heavy weapons to prevent anyone to gain entrance to the Library and retrieve the Index, which would eventually lead to the extinguishment of the Flood.

Library
"More humans...they must be after the icon."

- Rtas 'Vadumee to the Arbiter

However, a small UNSC Marine force led by Miranda Keyes and Avery J. Johnson was able to slip through, and in the end, the Arbiter, Rtas 'Vadumee, and half a dozen Special Operations Elites were able to slip into the periphery of the Library. There were a pair of gondolas, that when activated, autonomously brought their passengers into the upper tiers of the Library, where the Index was kept. While the UNSC was first able to seize a gondola, the Covenant were close behind. However, when the Flood began to screech, alerting the Covenant that they were in full force in the bowels of the Library, Rtas 'Vadumee took a pair of Special Operations Elite, holding them at the entrance to the gondolas to defend the rest from the Flood as the Arbiter took four Special Operations Elites on the second gondola, trailing behind the UNSC-held one.

"Humans! I'll get them."

- Tartarus

"That fool! He'll alert them to our presence!"

- First Special Operations Elite

"Look on the bright side, maybe if we're lucky, they'll shoot him down!"

- Second Special Operations Elite

The gondola's ride, however, was harrowing. Flood entered the gondolas, jumping from the upper levels and also crawling in underneath on their undersides, assailing both the UNSC troops and also the Arbiter and his quartet of Special Operations Elites. Tartarus, in his Phantom, attempted to provide cover fire for the Arbiter, using the three plasma cannons of his dropship to burn off any Flood on the upper levels of the Arbiter's gondola, but later, Tartarus chased after the UNSC-held gondola.

"Behold, the library of our lords!"

- Special Operations Elite "The humans are already inside, Arbiter! After them! I'll watch the perimeter. Hurry, Arbiter! Get the icon!"

- Tartarus

"We shall protect this vessel. It may be our only means of escape."

- Special Operations Elite

Finally, both gondolas ascended to the top levels of the Library, although the UNSC one arrived first, and a small UNSC force of six soldiers: four Marines (including Perez and McKenzie) led by Miranda Keyes and Avery Johnson, entered. Although many Combat Forms had been exhausted in the Flood's last-ditch attempt to stave off the gondolas, there were a large number of Infection Forms prowling the Library which killed off the four UNSC Marines as Keyes and Johnson advanced towards the core of the Library. Meanwhile, the Arbiter silently snuck in behind them.

"McKenzie, Perez, how's our exit? You hear me, Marines?...we got trouble."

- Sergeant Major Avery J. Johnson

Miranda stretched over a seemingly bottomless chasm, grasping for the Index, and then barely making it, securing it on her belt. Meanwhile, Sergeant Johnson shouted for the remaining Marines to report. When there was no response, the pair of UNSC personnel cautiously began to edge away from the core, with Johnson lifting his BR55 Battle Rifle at the ready while Miranda hefted her pair of M7/Caseless Sub Machine Guns. However, the Arbiter engaged his active camoflague, cloaking himself as he lunged at Johnson, headbutting him into unconsciousness, and as Miranda fired a spatter of bullets from her submachine guns, the Arbiter disarmed her, but before she could react, Tartarus entered with four of his Brute Captains. Tartarus used his Gravity Hammer, the Fist of Rukt, to stun Miranda and gravitically levitate her towards him, draping her over his shoulder and then clasping the Index and securing it for himself.

"The Icon...is my responsibility."

- Arbiter

"Was your responsibility. Now it is mine. A bloody fate awaits you and the rest of your incompetent race. And I, Tartarus, Chieftain of the Brutes, will send you to it!"

- Tartarus

"When the Prophets learn of this, they will take your head!"

- Arbiter

"When they learn? Fool, they ordered me to do it."

- Tartarus

With the Library clear and devoid of hostiles, the Arbiter demanded to have the Index, as he was personally ordered by the Prophet of Truth to secure it for the Covenant. However, unbeknownest to him, he had been betrayed by the Prophets, as were the entire Elite race. The Prophets had made the Brutes their champions, casting aside the physically inferior Elites.

Tartarus refused to give the Sacred Icon to the Arbiter, and instead, his Brute Captains leveled their Brute Shots at the Arbiter as Tartarus revealed the betrayal. The Arbiter jerked his neck up in horror as Tartarus swung his Gravity Hammer, sending a gravitic shock that sent the Arbiter into the bottomless chasm above which the Index was once situated.

"The release of the parasite was unexpected, unfortunate. But, there is no need to panic. In truth, this is a time to rejoice. A moment that all the Covenant should savor...for the Sacred Icon has been found. With it, our path is clear, our entry into the Divine Beyond guaranteed! The Great Journey is nigh...and nothing, not even the Flood, can stop it!"

- Prophet of Truth

Meanwhile, Tartarus brought the Sacred Icon to High Charity, where the Prophet of Truth exulted him and encouraged the Covenant to celebrate, for the Sacred Icon was secure, and that soon afterwards, that the Halos would be fired and the Great Journey would be brought upon the Covenant.

Introduction
However, the Covenant would not activate the Halos unimpeded. The Flood, who would be annihilated if the rings were activated, would soon attack the Covenant to prevent the activation, and the UNSC, who understood that all sentient life would be erased, too opposed the Covenant. Later, after the fragmentation of the Covenant into the Covenant Loyalists and the Covenant Seperatists, the Seperatists would understand the true intent of Halo and attack the Loyalists to prevent them from activating the ringworld.

"There is still time to stop the key from turning, but first it must be found. You will search one likely spot, and you will search another. Fate had us meet as foes, but this ring will make us brothers."

- Gravemind to SPARTAN-117 and Arbiter

Meanwhile, SPARTAN-117, who had jumped into the ocean, and the Arbiter, who had been thrust into the chasm of the Library, were both caught by plant-like tentacles and grabbed into the lower reaches of Installation 05, where they met face-to-face the Flood central sentient intelligence known as the "Gravemind", who explained to the Arbiter why the Halos must not be activated for the interests of galactic life. The Gravemind, holding both SPARTAN-117 and the Arbiter prisoner, explained that in his plan to prevent the activation of Installation 05 by the Covenant, he would manipulate Halo's teleportation grid, sending SPARTAN-117 to High Charity and search one likely spot where the Index was placed, and sending the Arbiter to the cliffs just beyond the Control Room, another likely spot.

Battle of High Charity
"The demon has entered the council chamber? Protect the Hierarchs! Seal the exits!"

- Tartarus

SPARTAN-117 was teleported by the Gravemind directly into the High Council Chamber of High Charity, where the Prophets of Truth and Mercy addressed the Covenant that the Sacred Icon was secure. Before SPARTAN-117 could kill both Prophets, they escaped by means of an elevator, while the doors were locked and waves of Honor Guard Brutes, Minor Brutes, and Grunts entered in an attempt to kill the supersoldier. Cortana managed to unlock the doors, and SPARTAN-117 chased through two towers and a set of corridors in pursuit of Truth before Cortana picked up the IFF transponder signals of UNSC Marines - prisoners of the Covenant being kept in two brigs in a multitiered detention block.

"Wait a minute! I'm reading Marine IFF transponders. The signals are originating somewhere below your position!"

- Cortana to SPARTAN-117

Cortana managed to reverse a central gravity lift, allowing SPARTAN-117 to enter the detention block. However, Tartarus had anticipated this, increasing security around the brigs while a massive firefight ensued as SPARTAN-117 released five Marines from two brigs, who assisted SPARTAN-117 in his pursuit of Truth to kill him and secure the Index.

"The Elites have failed to protect the Prophets, and in doing so, have put all our lives at risk. Let no warrior forget his oath, 'Thou, in faith, shall keep us safe, whilst we find the Path'. With my blessing, the Brutes now lead our fleets! They ask for your allegiance, and you shall give it."

- Prophet of Truth

However, meanwhile, the Covenant splintered in minutes after SPARTAN-117 emancipated the captive Marines. The Prophet of Truth made an epic announcement, and in three sentences over the loudspeakers of High Charity, put his plan to betray the Elites into action: he ordered all of the Covenant to follow the Brutes as their military commanders, and inevitably, the Elites, seething in hatred against the Brutes, took this as their final straw. Slighted by the Prophets, the Elites burst into full-out warfare on High Charity and across the rest of the Covenant empire against the Brutes. While the Grunts and Hunters followed the Elites, the Jackals and the Drones supported the Prophet-blessed Brutes. Warship crewmen began to open fire upon each other with small arms, and the Covenant fleets began to open fire against each other.

Truth's transmissions, however, allowed Cortana to triangulate his position, allowing her to direct SPARTAN-117 and his Marines in their hunt for the Prophet. The Covenant attempted to stop Cortana, but were unable to prevent her.

As SPARTAN-117 and the Marines reached the Hanging Gardens A, the first scene of intra-Covenant violence was seen, as Honor Guard Elites, Minor Elites, Hunters, and Grunts fought against Brutes and Jackal Snipers amongst the massive insectine plants. SPARTAN-117 and his men advanced to the Mid-Tower, where Rangers and Special Operations Elites entered the fray, and the Brutes unleashed their Drones into the combat.

Even as the imprisoned Marines were freed, the crews of the In Amber Clad were in peril. It appeared that the Gravemind double-crossed the UNSC, sending SPARTAN-117 hunting for the Index in the bowels of High Charity while the Gravemind teleported Flood forms into the UNSC frigate, overpowering the crew and seizing it. The Gravemind then teleported the In Amber Clad from the atmosphere of Installation 05, sending it into a Slipspace reversion over High Charity, where it plummeted uncontrollably, crashing into the Far Tower.

"Once the towers are clear, we'll drive them from the lower districts!"

- Tartarus

However, by the time that the small UNSC squad entered Hanging Gardens B, Covenant Seperatist resistance on High Charity had broken. In the second Hanging Gardens, the Covenant Seperatists fell back, leaving behind large numbers of Stationary Shield Generators, abandoning numbers of Grunts to beserking Brutes as the Elites fell back to the Far Tower and the Mausoleum of the Arbiter, drawing a last line of defense there. In the forward sections of the Far Tower, the Seperatists held a chokepoint bridge with a pair of plasma turrets, Special Operations Elites, and a pair of Hunter warriors. In the Mausoleum of the Arbiter, elitist Ultra Elites and Hunters fought against waves of attacking Brutes. Despite their efforts, the Prophets of Truth and Mercy, Tartarus, and a handful of Brute Captains were able to tunnel through the last Seperatist defenses to the far docking bays of the Far Tower. SPARTAN-117 pursued Tartarus, fighting through the Far Tower and the Mausoleum of the Arbiter to make it through to the Phantom pads.

"Your pal. Where's he going?"

- SPARTAN-117

"Earth...to finish what we started. And this time, none of you... will be left behind..."

- Prophet of Mercy's last words

The SPARTAN was too late, however. The Prophet of Truth ordered Tartarus to use the Sacred Icon in the Control Room of Installation 05, and activate the Halos. Tartarus took a detachment of Brute Honor Guards along with him in two Phantoms, along with UNSC prisoners Avery Johnson and Miranda Keyes. Truth and Mercy took a third Phantom to the Forerunner Ship - the central energy source of High Charity, and also a fully functional starship that the two remaining High Prophets were going to use to reach Earth, and "finish what [the Prophets] started".

Meanwhile, the Flood were escaping from the crashed hulk of the In Amber Clad. They seeped out of the rents in its hull armor, and also exhibited unexpected intelligence, commandeering its Pelican dropships and sending them over the surface of High Charity, crashing into the floors and releasing Combat Forms, and spilling Infection Forms out of the air from opened hatches. The Prophet of Mercy was beset by an Infection Form and died before he could reach his Phantom. However, Tartarus and Truth were able to depart before SPARTAN-117 could arrive.

"That structure at the center of the city! It's a Forerunner Ship...and Truth is heading straight for it! If he leads the Covenant fleet to Earth, they won't stand a chance. You have to stop him!"

- Cortana to SPARTAN-117

Despite the fact that SPARTAN-117 had failed to capture the Prophet of Truth before he could depart in his Phantom for the Forerunner Ship, it was still imperative that the SPARTAN chase after him and kill him, as if he marshalled the Covenant fleets to Earth to finish whatever he planned, the already besieged Earth would inevitably fall, despite the UNSC's best efforts.

At the time, Covenant Seperatist resistance had completely shattered on High Charity. There were none to little Elites nor Hunters remaining, and only several scattered Grunts. The Loyalists, however, retained a large number of Brutes, Jackals, and Drones. Despite the lack of