High Charity (Structure)
From Halopedia, the Halo wiki
High Charity is a mobile planetoid station and known as the Holy City of the Covenant, and specifically the Prophets. It is a large mushroom-shaped structure estimated to be 348 kilometers (216.108 miles) in diameter. At the apex of this "mushroom" is an opening for the launch of the Forerunner Dreadnaught. The stalk peters out to a point, with various branches leading off from it.
The interior of High Charity is effectively a massive city, built around the appropriated Forerunner Dreadnaught ship, which was used to power most of the city. The city itself contains many sacred locations to the Covenant, such as the Council Chamber, the Sanctum of the Hierarchs, and the Mausoleum of the Arbiter. As a construct, High Charity is very similar to the Unyielding Hierophant, the Repair & Refit station, containing many courtyards and other spaces throughout which attempt to seem natural. The interior of High Charity is, of course, laced with the Covenant's unique architecture, of a lighter tone than their naval vessels.
High Charity is important enough to the Covenant to wield its own personal fleets, consisting of dozens of battleships, carriers, and cruisers, making up some of the largest fleets in the entire Covenant, such the Second Fleet of Homogeneous Clarity, and the Fleet of Particular Justice.
High Charity is enormously sacred to the Covenant, being their major religious center. It is full of High Prophets, and Elite Councilors, and generally the leadership of the entire alien hegemony. Identity-wise, it can be likened to the human view on the UNSC Hopeful, albeit hundredfold.
History
Little is known of High Charity before its depictions in Halo: First Strike. It appears that the city stayed in one place for an extended period of time, as it was practical to set up a network of Slipspace probes to protect its position. Anything larger than a centimeter in diameter that drifted too close was obliterated, including ships that failed to transmit proper clearance codes within a millisecond of hailing.
Halo
Upon the discovery of Installation 04 by the Covenant, High Charity was supposed to perform a Slipspace jump to the Halo along with its fleet, where the High Prophets would activate the ring to send the Covenant on the Great Journey. They sent the Fleet of Particular Justice to secure the ring in preparation for High Charity's arrival, but they did not know about the Flood, and did not expect interference from the UNSC. When High Charity and its fleet arrived at Threshold, they found that both the Halo and the Fleet of Particular Justice had been utterly destroyed.
Halo 2
After The First Battle of Earth, the High Prophet of Regret sent the coordinates of Installation 05 to High Charity. The planetoid and its fleet arrived just in time to watch the Master Chief kill Regret. It then held position over Installation 05 until hostilities erupted between the Brutes and Elites, as a new Civil War of the Covenant broke out.
During the chaos of the war, the Master Chief infiltrated High Charity, as did The Flood, using the In Amber Clad to ferry legions of Combat Forms to the station, and Pelican dropships to spread Carrier Forms. Within the city a vicious melee ensued among Brute forces, Elite forces, and Flood, all bent on destroying one another. The unfortunate Master Chief was caught in the middle of this, but managed to escape.
Eventually, the Forerunner ship at High Charity's core took off, with both the Prophet of Truth and Master Chief inside, leaving behind Cortana. It appears that the Covenant forces on both sides completely abandoned High Charity afterwards, and it was completely infested by the Flood, as the Flood organism known as Gravemind took complete control of the Sanctum of the Hierarchs, using the Council Chamber itself as his "throne room."
Post-Halo 2
As High Charity and Delta Halo were rapidly falling to the Flood, a massive battle between Elite and Brute held ships continued in the space around the city. The Elites eventually succeeded in driving away the Brutes (or they possibly retreated on orders from Truth to assist in the conquest of Earth). The Elites formed a large fleet and quarantined High Charity, attempting to prevent the Flood from infesting any other systems.
Halo 3
After the Second Battle of Earth, a message from Cortana warned that the Gravemind was speeding the infested High Charity toward Earth, and the portal to Installation 00. During the Battle of Installation 00, High Charity appeared through the portal and narrowly missed the Elite carrier, Shadow of Intent. It disgorged Flood dispersal pods (several of which crippled said carrier) and crashed on the Installation, completely unrecognizable from what it originally was apart from the exterior shape.
After stopping Truth from activating the rings, the Master Chief single-handedly waded through the Flood-infested High Charity and retrieved Cortana. At her recommendation, he overloaded the engine core, and escaped. High Charity was completely destroyed in the resulting explosions.
