Fall of High Charity

The Battle of High Charity was a large battle for the control of the Covenant capital world High Charity among the Covenant Empire, the Covenant separatists, limited United Nations Space Command forces, and later, the Flood. The battle marked several significant events, including the start of the Great Schism, SPARTAN John-117's pursuit of the Prophet of Truth to Earth, and the Flood invasion and infestation of High Charity.

The Fracturing of the Covenant
With the Jiralhanae, who directly competed with the Sangheili, slowly gaining the favor of the Prophets, it was only a matter of time before the latter were overthrown and open warfare began between the two parties. However, multiple events helped bring about the battle.

Recent failures of the Sangheili leading up to the battle, including the loss of Installation 04 and the assassination of the Prophet of Regret by the UNSC, damaged the reputation of the Sangheili and further empowered and emboldened the Jiralhanae. These events spurred the Changing of the Guard, giving the Jiralhanae the duty of protecting the Prophets - an honor traditionally held by the Sangheili, further damaged their reputation and position within the Covenant.

Battle of Installation 05
However, while the eventuality of the Battle of High Charity was a foregone conclusion, its scale was not. The Prophet of Regret's wayward mission to Earth brought High Charity, John-117 and the to Installation 05. With the Gravemind already released and plotting its way off of the Halo, this would set the tables for the invasion by both the Flood and the legendary 'Demon'.

An attempt to kill SPARTAN-117 from orbit had failed and instead threw him into the clutches of the Gravemind. It would be Tartarus, however, who put the final pieces of the puzzle into place - some of them inadvertently. After the Arbiter successfully acquired the Index from the Library, Tartarus attempted to execute him by firing a burst from his Fist of Rukt at the Arbiter and knocking him into the depths of the Library. He then took the Index and Commander Miranda Keyes and Sergeant Major Avery Johnson as prisoners back to High Charity where the Prophets of Truth and Mercy waited.

Gravemind
The Arbiter, however, would not be slain there. The Gravemind had other plans for him along with SPARTAN-117. The Index was now in the hands of the Covenant, and as ignorant as they might be to the true purpose of the Halos, they were fully intent on firing them - an act that would prove fatal to the Gravemind should it occur. As such, he knew that the Halos must not be fired, and for that he brought two of the finest warriors and the ones most likely to stop the catastrophe. He sent SPARTAN-117 to High Charity and the Arbiter to the local installation's Control Room - the two most likely places for the Index to be. He then prepared to bring the other part of his plan into action - the invasion of High Charity.

Master Chief's entrance
"Boo."

- Master Chief to a Grunt filming the speech. The Grunt flees afterward.

The battle began in the Council Chamber. The Prophet of Truth (with the Prophet of Mercy at his side) was giving a speech to the Covenant acknowledging the release of the Flood and announcing Tartarus' successful acquisition of the Sacred Icon. As Truth's speech drew to a close, SPARTAN-117 was teleported into the room by the Gravemind, appearing right beside the Grunt who was filming the speech. He acquired the Grunt's Needler and aimed it at the Prophets, but the Brutes protected the Prophets in order for them to escape.

Once he secured the Council Chamber, SPARTAN-117 inserted Cortana into High Charity's security systems so she could open the doors to the room. She then opted to remain in High Charity's system as she felt it would provide her the greatest opportunity to aid him. With the Index clearly in the possession of the Prophet of Truth, the Spartan chased after the fleeing Prophet.

Rescue
"Listen up, Marines! the Chief's hunting a Prophet, and you're going to help him kill it."

- Cortana

Shortly after beginning his hunt, Cortana noted that there were Marine transponders near the Master Chief's position. After raiding the prisons, five Marines joined the Spartan in his hunt for the Prophet.

The Great Schism begins
"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

Soon thereafter the Marines were rescued by the Master Chief and the Prophet of Truth declared that the Brutes were now in charge of the stationed Covenant fleets. The Brutes then instigate a genocide of the Elites, as secretly ordered by Truth. War broke out on High Charity and the Great Schism began. As John-117 and his marines moved around High Charity, they bore first-hand witness to the fracturing of the Covenant, sometimes opting to watch as the two sides fought rather than becoming directly involved. The Brutes focused on attacking Elites in the towers of the city, then spread out to the lower levels. The Elites that survived the initial betrayal retreated to the Mausoleum of the Arbiter to make a last stand, supported by many Hunters and Grunts. The causeway leading to the Mausoleum became a battlefield choked with dead from both sides. However, the Brutes were eventually able to push through, and fighting spread to the central chamber of the Mausoleum itself.

The Flood invades
"Slipspace rupture. It's In Amber Clad! Hailing... No response. She's crashed into another tower ahead of our position. I'll keep trying to make contact, but I'm not registering any human vital signs."

- Cortana

Sometime later, In Amber Clad entered High Charity via Slipspace, flying across the City before crashing into a tower. Cortana tried to contact the ship but registered no life signs on board. It would be sometime before the true nature of In Amber Clad's arrival would be known: it had been captured by the Flood and it was they who had flown it in. The various short-range crafts it possessed launched and spread the Flood infection throughout the city. This single event changed the course of the war.

Mercy Falls
"Let him be. The Great Journey awaits no one, brother...not even you."

- Truth

In the race to capture the Installation 05's Index, the Spartan was moments behind. The Prophet of Truth made it to his escape Phantom and handed the Index over to Tartarus to incept the Array's process. Tartarus prepared to take the Index along with UNSC prisoners Commander Miranda Keyes and Sergeant Major Avery J. Johnson to Installation 05 to activate the Halo.

Before they could leave, however, Flood infection forms attacked them. Tartarus and his Brutes tried to defend the Prophets of Truth and Mercy, but one of the Infection Forms got through their screen and landed on Mercy. Tartarus tried to remove the Infection Form, but the Prophet of Truth ordered him to let the Prophet die. A surprised Tartarus proceeded down to the surface.

Departure
By the time John-117 had reached the Prophet of Mercy, the Prophet was nearly dead and the Marines he had rescued had similarly fallen. In his interrogation of the Prophet, he learned that the Prophet of Truth was fleeing towards Earth. Cortana determined that Truth was heading towards the Forerunner ship which stood in the middle of the City.

With the Arbiter still on Installation 05 and Cortana stating that she could detonate In Amber Clad's reactors if it was needed to destroy the Halo installation, the SPARTAN proceeded to follow the Prophet of Truth and attempt to board his ship before it left. However, Cortana chose that she couldn't trust the fail-safe detonation of In Amber Clad to any copy of herself and had to remain behind.

While Cortana tried to stall the launch of the Forerunner ship, the Master Chief moved through the maze of High Charity, fighting Flood and Covenant alike to board the ship. During that time, Cortana realized that the ship was actually the power source for High Charity. In the end, he got on board with mere seconds to spare. Before he left, the Chief promised to come back for Cortana (which he later did, rescuing her and destroying High Charity).

The Great Schism
"The Covenant just destroyed two of their own ships! And I'm hearing reports of small arms fire throughout their fleet."

- Cortana

The battle became the first battle of the Great Schism. Warships around High Charity continued to fight well after the battle on the surface of High Charity itself was over. However, whether the battle's outcome would have any lasting impact on the outcome of the Great Schism is currently unknown. That said, the fact that neither side was able to acquire control of High Charity likely limited any major gains that were to be had.

Tartarus and the Index
Tartarus eventually arrived to the Control Room with Miranda Keyes and began the firing sequence for Installation 05. However, the Chieftain would eventually fall to the Arbiter and the firing sequence would be aborted, putting all remaining Halo Installations into standby mode, readying them for a final activation from Installation 00.

The Prophet of Truth and John-117
The Prophet of Truth and SPARTAN-117 would eventually reach Earth aboard the Forerunner Ship and participate in the Battle of Earth. Upon its arrival, Lord Hood ordered the ship to be destroyed, but SPARTAN-117 identified that he was aboard the ship and wanted to finish the fight. SPARTAN-117 was hoping to kill Truth before leaving the Forerunner ship, but was unable to do so.

High Charity
The Flood eventually gained full control of High Charity and the Gravemind took up residence in the fortress. He resided in the Prophet's Council Chamber, using it as his "control room." Cortana, who was stranded in High Charity's computer systems, was questioned by the Gravemind who turned the city into a massive Flood Hive. After the Forerunner Dreadnought decoupled from the city, a backup reactor is activated by the Flood and High Charity is fully powered once again. During the Raid on High Charity, the city was destroyed by the Master Chief who destroyed the reactor, which caused it to go critical.

Cortana
Cortana remained behind on High Charity in the clutches of the Gravemind who interrogated and tortured her. This drove her to the point of rampancy, but she managed to send a message to Earth and hold onto an important secret. Ultimately, she was rescued by the Master Chief during the Raid on High Charity and High Charity was destroyed during her rescue.

List of appearances

 * Halo 2
 * Halo: Ghosts of Onyx