Battle for the Control Room (Installation 05)

The Battle for the Control Room was an engagement during the latter stages of the larger Battle of Installation 05, in which Sangheili forces led by Arbiter Thel 'Vadamee fought to reach the Jiralhanae-held control room to prevent the activation of the installation, ultimately forging an uneasy alliance with the surviving crew of the UNSC In Amber Clad.

Background
Following his brash and unprepared arrival at Earth, the High Prophet of Regret was forced to withdraw as his small excavation fleet was overwhelmed by the planets defenses and his ground forces in the city of Mombasa were pushed back by UNSC ground forces. The Prophet had his flagship, the assault carrier Solemn Penance perform a slipspace jump directly over New Mombasa, having discovered the location of Installation 05 using information he had gleaned from the Luminary recovered on Meridian. Unbeknownst to the Prophet, his ship was followed through slipspace by the UNSC frigate In Amber Clad. The two warships arrived in the Coelest system on November 2, 2552. As the Solemn Penance deployed ground forces to the surface, the human vessel deployed a strike force of ODSTs led by Spartan John-117 to assassinate the Covenant Hierarch. Despite the arrival of the Covenant holy city High Charity and it's vast defense fleet, the Covenant were unable to prevent Regret's death at the hands of the Master Chief. Truth instead recalled the flotilla of Phantoms the fleet had dispatched and allowed his fellow Hierarch to die, having the fleet glass the temple instead.

The following day, the Prophet of Truth had the Sangheili of the Covenant Honor Guard replaced by the Jiralhanae, using the assassination of Regret to discredit the Sangheili and further his own agenda to ultimately take sole control of the Covenant. The Prophet of Truth sent the Arbiter of the Covenant, disgraced former Supreme Commander of the Fleet of Particular Justice Thel 'Vadamee to the Sentinel wall encircling the Library in order to deactivate the shielding and allowing the Covenant to secure the Activation index that would allow them to ultimately activate the ring. While Thel was successful in this task, he inadvertently allowed the Flood within the quarantine zone to spread and infest both Covenant troops and UNSC personnel of the In Amber Clad and gain access to weapons, vehicles and ultimately, control of the human frigate which they would later use to infest High Charity. After fighting through hordes of Flood and Sentinel defenses, Thel and a team of Special Operations Sangheili made it to a gondola that would take them into the Library, following in close pursuit of remaining UNSC forces led by Commander Keyes and Sergeant Johnson. Thel engaged Keyes and Johnson immediately after the former had retrieved the Index, incapacitating Johnson before Tartarus arrived, seizing both Keyes and the Index. As Tartarus' Jiralhanae surrounded Thel, the chieftain revealed his intent to initiate the Great Schism on Truth's orders, before knocking the Arbiter into a deep pit below the Library. A short time later, Tartarus' second-in-command, Captain Melchus, led a contingent of heavily-armed Jiralhanae into the control room, where the Sangheili High Councilors and many of their former Honor Guards were gathered to witness the activation of the ring and the culmination of the "Great Journey". The Jiralhanae proceeded to massacre the Sangheili, catching the unprepared Councilors off-guard. While they fought back, all of the Sangheili were eventually killed, with only one surviving due to his fall from the platform being broken by the dead bodies of his compatriots.

The Arbiter's own fall was broken by the Flood Gravemind, who resided deep below the Library. Here, Thel was confronted with not only John-117, who had similarly been captured by the Gravemind, but also the monitor of Installation 05, 2401 Penitent Tangent and the reanimated corpse of the Prophet of Regret. While both the Gravemind and the Master Chief attempted to tell Thel of the true purpose of the Halo rings, the Sangheili refused to listen. The Gravemind promised to show the defiant Arbiter the truth, using the installation's teleportation grid to send Thel to the cliffs near the control room.

The battle
"Thel 'Vadamee"

- Tartarus

Thel 'Vadamee arrived on a cliff overlooking Installation 05's control room. He immediately located a plasma rifle lying on ground smeared with Sangheili blood. As he moved towards a downed Sangheili Minor, he heard and saw distant plasma fire as Jiralhanae troops killed off the last remaining Sangheili on the cliffs. In his final breath, the Minor warned Thel of the massacre of the Sangheili Councilors by the Jiralhanae. Taking the fallen warrior's energy sword, the Arbiter slew a trio of Jiralhanae that were pondering what to do with the Sangheili corpses. The captain in command of the Jiralhanae pack on the cliff ordered his men to find the Brutes that had failed to report in. Thel promptly engaged the pack in combat, and was assisted by a camouflaged Special Operations Sangheili who emerged from the nearby structure. Once the area was clear, the Special Operations Sangheili confirmed the death of the Councilors and vowed to avenge them. A trio of Covenant drop pods arrived in the canyon; Sangheili reinforcements including a Zealot who was eager to go to war against the Brutes. The group of Sangheili formed up and moved through the structure into a cave with several Forerunner platforms where Jiralhanae and Kig-Yar patrolling. The group of Sangheili fought their way through the cave, killing groups of Jiralhanae, Kig-Yar and Yanme'e while unpinning a pair of Unggoy who supported the separatist cause. Thel and his allies fought their way through several more rooms containing Jiralhanae and Kig-Yar occupying positions fortified by Shade turrets and encountering scattered Sangheili and Unggoy who assisted the separatists in their push. Eventually, the group made it outside the structure, where they eliminated a large pack of Jiralhanae before commandeering their parked Ghosts. Now mobilized, Thel and his allies attacked a larger Covenant camp, overcoming several waves of Jiralhanae and Kig-Yar reinforcements. In the next camp, they assisted a cowering Unggoy by killing it's Kig-Yar overseer. The Unggoy mounted a nearby Shade and assisted the team in destroying the rest of the Covenant forces in the camp, including a Jiralhanae-operated Spectre which arrived from the camp's exit. The separatist movement pressed onward, wiping out a small camp of Kig-Yar before reaching a shallow river where Jiralhanae forces attempted to detonate a number of plasma batteries with their Brute Shots. This attempt failed and all of the Covenant troops were wiped out. Thel and his allies arrived at a heavily-fortified encampment where the Jiralhanae had stockpiled an assortment of UNSC and Covenant weaponry. The team were forced to destroy a pair of Wraiths, as well as a number of Kig-Yar snipers before they could enter the structure. Over the course of the battle, several more Sangheili arrived in drop pods to reinforce the group. As they made their way through the structure, the Sangheili accompanying Thel expressed their disgust at the weaponry the Brutes had stockpiled. A final group of Covenant including a pair of Ghosts guarding a nearby cave attempted to halt the separatists but were destroyed. Thel proceeded through the cave alone.

On the other side of the cave, Thel was slowly approached by a Wraith. Unsure of the vehicle's allegiance, Thel raised his carbine but was relieved when Commander Rtas 'Vadumee revealed himself to be the pilot. The Arbiter informed 'Vadumee of the slaughter of the Sangheili Councilors, to which 'Vadumee retorted that the Prophets had been foolish to trust the Jiralhanae. As the pair conversed, a pair of Phantoms flew overhead, towards the control room. One of the dropships deposited Tartarus and the captive Miranda Keyes and 343 Guilty Spark. The two entered the control room, and the door was sealed behind them.

Thel, remembering the words spoken by the Gravemind, stated his intention to get inside, to which 'Vadumee revealed he knew a way to break the doors. A Spectre piloted by a Special Operations Sangheili arrived, allowing the Arbiter to mount up. With the Spectre and 'Vadumee's Wraith, the group made their way through the canyon, engaging a unit of Jiralhanae-operated Ghosts and a Wraith. As another set of Forerunner structures came into view, re-purposed as the Bastion of the Brutes, 'Vadumee suggested they use the adjacent Protos Scarab to blast through the reinforced doors of the control room. A Phantom attempted to strafe the separatist vehicles while a pair of Wraiths and another pack of Jiralhanae guarding the entrance to the structures fought to keep the Sangheili out. Eventually Thel and his allies managed to defeat the Brutes. 'Vadumee declared his intent to retake a nearby CCS-class battlecruiser from the Jiralhanae, after waiting to ensure no Covenant reinforcements followed the group into the structure. Proceeding inward, Thel encountered another Special Operations Sangheili and a Mgalekgolo pair. After assuring the Arbiter that the gestalts were on the separatist side, the group made their way through a series of corridors and rooms and across an indoor cave, clearing out Jiralhanae positions as they went. On an outdoor bridge, a unit of Kig-Yar, Yanme'e and a Phantom engaged the Sangheili and Mgalekgolo. As the Covenant ground troops, the Phantom retreated allowing the Arbiter and his group to proceed into a holding area where several surviving Councilors and another Mgalekgolo pair were contained behind shield doors. Thel and his allies attacked, releasing the captives. Between them, they quickly wiped out the Jiralhanae presence in the room. On the exterior platform, the Jiralhanae were preparing to execute three Marine prisoners, among them Sergeant Johnson. Just as Tartarus radioed the Brutes to kill the captives, Thel and his forces attacked the Jiralhanae, catching them off guard and easily slaughtering them, but allowing the humans to take control of the nearby Scarab.

A tense standoff ensued, with the human-controlled Protos Scarab aiming it's focus cannon at Thel. Instead of firing, Sergeant Johnson proposed an alliance, suggesting that they work together to stop Tartarus from activating the ring, something they both knew would mean the deaths of all of them. With a shared goal, and no alternatives, Thel agreed. A number of Sangheili landed their Banshees on the platform, allowing Thel to take control of one of them. Using the Banshee, Thel assisted Johnson in destroying a number of Jiralhanae-piloted Wraiths, Spectres, Banshees and Shade turrets while the Scarab made its way toward the control room. After arriving on the beach in front of the control room, Johnson used his Scarab's focus cannon to melt through the door. Thel proceeded into the control room alone, passing through a heavily-scorched corridor before arriving in the first room, where a number of Jiralhanae including several Honor Guardsmen arrived to stop him. Despite putting up a furious resistance, the Brutes soon fell and the Arbiter made his way inward. As Tartarus attempted to threaten Miranda Keyes to insert the Activation Index into the control room's Core, Thel arrived, ordering Tartarus to stop. As the surprised Jiralhanae chieftain turned to face the Arbiter, Thel announced that even the Hierarchs did not know everything about Halo. As Tartarus' bodyguards stepped forward menacingly, Tartarus halted them, angrily retorting that the Arbiter was speaking heresy. Thel asked 343 Guilty Spark to explain the purpose of the Halo Array, but Tartarus furiously seized the monitor, warning him to not say anything more. Sergeant Johnson stepped in, aiming a particle beam rifle at the chieftain's head. As Tartarus' bodyguards snarled in fury, Johnson calmly threatened Tartarus to order them to stand down or he would fire on the chieftain. Sensing his life in danger, Tartarus brought his Jiralhanae into check. Now free to continue, 343 Guilty Spark proceeded to explain to the gathered forces the truth behind the purpose of the Halo Array. Rather than being a means of transcendence as the Hierarch's had promised, the rings were revealed to have been built by the Forerunners as a weapon of last resort against the Flood, used to eliminate all potential Flood hosts throughout the galaxy, adding that the Forerunners themselves had been wiped out by the superweapons. Stunned by the monitor's words, Thel told Tartarus that the Prophets had betrayed them all. Despite being confronted with the truth, Tartarus remained blinded by his loyalty to the Hierarchs and his hatred of the Sangheili. The Chieftain hurled Spark at Sergeant Johnson, knocking the Marine down and using the opportunity to force Commander Keyes to insert the Index into the Core, beginning the activation sequence. As the Halo charged up, Tartarus activated his invincibility shielding and hefted his war hammer in preparation for battle. A group of Sangheili charged into battle alongside Thel and Johnson, easily wiping out Tartarus' Jiralhanae bodyguards. The chieftain leapt to the central platform, followed closely by Thel and his Sangheili while Johnson remained on the catwalk to provide covering fire. Despite being heavily outnumbered and faced with multiple high-ranking Sangheili, Tartarus was able to use the Fist of Rukt along with his incredibly-durable energy shield to inflict heavy losses on his attackers. Using the gravity hammer to easily dispatch of any Sangheili who attempted to attack with energy swords and able to shrug off barrages of plasma rifle and needler fire, it seemed as though Tartarus was invulnerable to attack. Only several consecutive shots from Johnson's particle beam rifle was able to bring the chieftain's shield down temporarily. Using this to his advantage, Thel managed to wear Tartarus down as his fellow Sangheili engaged Jiralhanae reinforcements. As they battled around the control room, Commander Keyes conversed with 343 Guilty Spark, eventually forcing the monitor to reveal that she could only stop the activation if she physically removed the Index, something she couldn't do while Tartarus was alive. Eventually Tartarus succumbed to the heavy damage inflicted upon him and fell before the Arbiter allowing Commander Keyes to run for the platform and remove the Index from the Core moments before the ring could fire. This prompted the installation to send out a pulse that set the remaining Halo rings to standby mode, ready to be activated from Installation 00.

Aftermath
Despite the death of Tartarus, the Prophet of Truth was already heading for Earth, where his personal fleet had been excavating the buried portal that would lead to the Ark for the last two weeks, it's presence having been partially revealed following the Prophet of Regret's slipspace jump on October 20. Commandeering the Forerunner Dreadnought at the heart of High Charity, the sole remaining Hierarch left the holy city as it fell rapidly to the Flood, with Spartan John-117 stowed away onboard. Commander Keyes and Johnson, having learned the location of the portal from Spark, realized the necessity of getting to Earth before Truth, and they, along with Thel 'Vadam would depart from the Coelest system while Sangheili ships led by Rtas 'Vadumee remained to quarantine the installation, glassing the surface of the ring and destroying any Flood-controlled ships that attempted to escape. Despite this, a a single battlecruiser managed to escape the quarantine and make a slipspace jump to Earth, with ships of the Fleet of Retribution in pursuit.

List of appearances

 * Halo 2
 * Halo: Broken Circle
 * Halo 2: Anniversary
 * Halo Mythos
 * Halo: Official Spartan Field Manual