Victorious Avowal

The machinations of the Prophets that brought about the Great Schism stretch back decades, and many contingency plans were put into place in the event of failure. Victorious Avowal was established by the Prophet of Mercy as a safe haven for San'Shyuum in a galaxy hostile to their existence, set up under a veil of such secrecy that even the Prophet of Truth knew little of it, and the High Council nothing. Selecting the most advanced technology, the most skilled scientists, and enough servants and guards to last for decades, long enough to rebuild from secret, Victorious Avowal also became a planetary fortress - network of orbital laser satellites created a virtually impenetrable barrier against a possible invading fleet, powered by a Forerunner relic discovered in the northern hemisphere. Enough infrastructure was established to allow the local forces to provide whatever was needed of a post-Schism Covenant, and waited.
As the Schism erupted, the defence fleet began to tear itself apart as Jiralhanae ships turned on the Sangheili ships. Mercy had planned it well - while the Sangheili have normally enjoyed the advantage with their superior skill at space combat and familiarity with their ships, Mercy selected only seasoned Shipmasters from the Ministry of Tranquillity's scout fleet, each more than capable of going toe-to-toe against a Sangheili ship. He also selected more of them - the Jiralhanae-led force outnumbered their Sangheili counterparts nearly three-to-one. Nevertheless, the Sangheili's tactical and strategic skill meant that by the time the battle was over, out of two hundred ships less than a dozen Jiralhanae-held warships had survived, narrowly outliving their Sangheili counterparts. Hearing of the Schism, the Minister of Preservation, local governor of the planet, refused to allow the fleet to make exploratory forrays into the wider galaxy to ascertain the scale and scope of the Schism, believing that leaving the planet undefended would be a disaster. While the laser satellites would prove formidible, there were ways to circumvent them, and Preservation did not wish to give any enemy so much as a remote chance - the survival of his species was too important. As the Schism raged around them, Victorious Avowal became isolated from the conflict, with none of the major factions so much as suspecting its existence.
Had the UNSC, Blood Covenant or Sangheili Armed Forces stumbled upon it, the result would have been catastrophic for the planet - the potential technological leap in understanding would be an enticing target, and the unpopularity of the Prophets would only create more determination behind any attack. The fact that virtually every faction was scouring the cosmos, searching for each other's inhabited systems and vital strategic points makes Victorious Avowal's continued secrecy an astonishing achievement, and when it finally was discovered in 2559, it was by a New Covenant scout force seeking Blood Covenant territory. The initial standoff was tense and threatened to see the first time two Prophet-led factions had fought each other since the San'Shyuum Civil War nearly five thousand years ago. Eventually, however, the ships of each side managed to establish contact and the galactic situation was explained to the locals. After brief negotiations, the Prophet's of Victorious Avowal agreed to merge with the New Covenant, allowing the latter access to their treasure troves of technology, in exchange for enhanced protection measures - as the merger became complete, the New Covenant made the colony their new capital world, its extensive defensive network and inaccessibility proving ideal. When the Second Great War erupted, two of the surviving Hierarchs, Devotion and Protestation, were present as the Great Upheaval began, and the Governors of Contrition began seizing the assets of the New Covenant to try and reform it into a Sangheili-led Great Journey-devoted faction. Forming the core of a breakaway "legitimate" Covenant, the two surviving Hierarchs would use Victorious Avowal as a launch site for a defensive campaign, driven back until they were forced to turn to the UNSC and Sangheili for assistance, neither eager to see the activation of the Halo Array by rogue Sangheili fanatics. The planet would see the second treaty signed by the three factions, this time concluding a formal peace during the duration of the crisis. This treaty was never revoked, and after 2572 the crippled remnant Covenant existed in a state of uneasy but official peace with the Sangheili and humanity, with Victorious Avowal continuing to serve as the capital.