Raid on High Charity

"Chief...you've found me."

- Cortana to SPARTAN-117

The Raid on High Charity also known as the Second Battle of High Charity, was a small engagement between the United Nations Space Command and the Covenant Separatists against the Flood in late 2552 on the crashed planetoid of High Charity upon the surface of Installation 00.

Introduction
Prior to the Second Battle of High Charity, the Flood had seized the Covenant mobile home planetoid of High Charity from the divided Covenant Seperatists and Covenant Loyalists during the Battle of Installation 05 and the opening of the Covenant Civil War. A small UNSC force was present during the First Battle of High Charity, and although many UNSC personnel fell to the Flood, SPARTAN-II supersoldier SPARTAN-117 managed to escape, although the UNSC artificial intelligence Cortana was left behind during the operation.

The Flood significantly floodformed High Charity, initially spreading metastizing tendrils and biological growths throughout the planetoid and cutting power while spreading spores into the air, but later, after a short period, completely remodeled the planetoid. The doors were replaced with biological portas and the walls were decked with infested biomass with incubation sacs and fleshy growths. It was no longer recognizable as a Covenant installation, but rather a Flood hive from the interior. All remaining Covenant on the planetoid were killed and/or infested. Cortana surrendered to the Flood for her own safety and was corrupted.

The Gravemind, with his newfound space station with billions-trillions of Flood, planned to attack Earth, the UNSC/Covenant Seperatist stronghold, and infest it with Flood. However, there he found a Forerunner Portal which led from Earth to Installation 00: the Ark, a center from which all the Halo Installations could be simultaneously and remotely fired. Sensing that was the greater threat, the Gravemind slipped High Charity through the portal, sparing Earth instead for the Ark. However, during the Slipspace transition, High Charity emerged in the fray of the Battle of Installation 00, and parts of it crashed into the Covenant Seperatist Assault Carrier Shadow of Intent. Parts of Flood-infested High Charity were sheared off and crashed into the installation below while the Assault Carrier was crippled. However, High Charity crashed into Installation 00's surface, appearantly from damage from the Slipspace transition or poor piloting that is the normal of the Flood. While Flood exited and spread across the Ark, infesting the Citadel and also the Control Room, large amounts of Flood still took residence within the crashed hulk.

On the Ark, however, its forges were manufacturing a new Halo Installation to replace the lost Installation 04 which was destroyed earlier on in the year. The Covenant Seperatist/UNSC alliance realized that in order to contain the Flood outbreak on Installation 00 spread by the crashed High Charity, they needed to flee and then activate the Halo, sterilizing the Flood on the Ark. However, Cortana, the lost UNSC artificial intelligence still within High Charity, was the sole owner of the Index necessary to fire the Halo installation. While Sergeant Major Avery J. Johnson and the Arbiter organized a systematic Seperatist/UNSC withdrawal from Installation 00, SPARTAN-117 ventured into the crashed High Charity via Banshee fighter to retrieve Cortana and rescue her, and also secure the Index to fire the incomplete Installation 04 being rebuilt on the Ark.

Beginning
SPARTAN-117 entered the crashed High Charity through a hole in the planetoid's surface in the western part of the station, and then proceeded inwards to the center in a quest to find Cortana. While at first he met only light resistance of just Infection Forms, soon, the Flood began to take notice of his intrusion, sending waves of Stalker Pure Forms to search for him and then deploying Combat Forms and Tank Pure Forms to assail him with Carrier Forms lumbering behind and Ranged Pure Forms on the walls opening fire on the SPARTAN while closer-ranged Flood attacked him directly. The strife began to intensify because of the numbers of Elite and Brute corpses scattered on the ground, which were easy targets for reanimination from the massive numbers of Infection Forms, and also because of the closely-packed claustrophobic tight quarters, whose walls were pulsing with Flood biomass.

Soon, the Gravemind began to take notice of SPARTAN-117, contacting him in enigmatic and disorienting transmissions at first demanding why he had come, wondering if SPARTAN-117 "sought forgiveness". Later, he realized that SPARTAN-117 was seeking Cortana, and then boasted that he had somehow merged with Cortana, and together they were "two corpses in one grave". Cortana began to make intense transmissions to SPARTAN-117 where it appeared that she was rampant: her voice began to fracture into voices of different pitch and she adopted a chilling high-pitched giggle as she rambled in incoherent words.

However, moving his way inwards, SPARTAN-117 managed to navigate a tall infested chamber, reaching the top and making it to High Charity ' s reactor room.

Upon reaching the next room the Master Chief encountered Cortana who was trapped in a Stasis Field. He broke the Field finally keeping his promise to her pointing out that he always keeps his promises. She also still had the Index that they needed. Cortana then re-entered the Data Chip that she exists in when she's with the Master Chief finally escaping High Charity's systems. The two then make their way back to the Reactor Room where Cortana tells the Master Chief to destroy High Charity to buy them more time to activate the Replacement Halo. The Master Chief then blasts the Reactor Pylons causing High Charity's reactor to start to go critical. The two make their way through the exploding city and encounter the Arbiter who has come to help. The three escape in a crashed but intact Pelican as High Chairty's reactors detonate destroying High Charity and all the Flood on it. Unfortunately the Gravemind somehow survived and begins rebuilding himself on the Replacement Halo.