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Concurrent:	Human-Covenant War
Next:	Blooding Years
Great Schism
Date:	9th Age of Reclamation—2nd Age of Abandonment/40th Age of Conflict November 3, 2552 — December 30, 2552 ("short" definition) November 3, 2552 — June 16, 2566 (conventional definition) November 3, 2552 — ongoing ("long" definition)
Location:	Milky Way (mainly Orion and Sagittarius Arms) Installation 00 (extragalactic space)
Outcome:	Schismatic victory
Belligerents Covenant / Loyalists Torchbearers Schismatics Singular Bond Concord of Reconciliation United Nations Space Command (allied) Flood Commanders High Prophet of Truth† High Prophet of Mercy† Apex Chieftain Tartarus† Warmaster Anotatus† Warmaster Storbum† Warmaster Cronus† Chieftain Belgarum Chieftain Vargax Chieftain Maractus Chieftain Lydus Chieftain Vanthor Chieftain Gorgothus Arbiter Thel 'Vadam Fleetmaster Rtas 'Vadum Councilor Srafal 'Amath Councilor XXXX Fleetmaster Pree 'Venkata Fleetmaster Nerit 'Mulaparthan Imperial Admiral Xytan Jar 'Wattinree† Imperial Admiral Gervul Jar 'Shaol Minister of the Common Weal Gravemind†

The Great Schism, widely known as the Great Betrayal or the Undoing, was a major conflict that marked the religious and political splintering of the Covenant. With the Writ of Union sundered, High Charity infested by the Flood, most of the High Council dead or scattered and the lineage of Hierarchs broken, the Covenant ceased to exist as a unified polity.

The Great Schism began when the High Prophet of Truth ordered the "Changing of the Guard", the replacement of the Sangheili Honor Guards with Jiralhanae. Though nominally justified by the Sangheili's failure to protect the High Prophet of Regret from his assassination by the "Demon", in truth this had been long planned by Truth, who wished to elevate the Jiralhanae to military leadership positions while expelling the Sangheili from the Prophets' side. From there, events quickly spiraled out of control, leading to an all-out civil war in the holy city of High Charity between the Loyalist and Schismatic factions.

A murky conflict all-around with numerous affiliations and subjective viewpoints that came and went with time, the Great Schism has no agreed-upon ending date, and the dating of its conclusion on depends on how broadly the conflict is defined. While the Prophet of Truth was slain in the final days of 2552, many of the Loyalists remained, and the resulting cascade of conflicts lasted for decades if not centuries. The initial Loyalist-Schismatic conflict is generally regarded as having ended in 2566 with the Pact at Unkarath, between the Concord of Reconciliation and the largest remaining master-packs that still remained of the Torchbearers. According to some interpretations, however, the Schism will not be truly over until the spiritual communion of the Holy Ecumene has been restored.

Background and causes

While the Great Schism' exact causes have been widely and incessantly debated since it began, it is universally agreed that it did not arise out of nowhere and had many direct and indirect causes both long- and short-term.

Aftermath of the Second Illumination

There had been an undercurrent of general dissatisfaction among the Sangheili nobility for nearly a millennium. The Second Illumination reconsolidated power to High Charity and its ministries, which created long-standing tensions that never quite died away in all corners of the Holy Ecumene. The nobles had come to romanticize the Covenant's earlier ages, when Sangheili lords might rule over entire star clusters with little interference from High Charity for centuries, and enjoyed the entirety of the wealth and bounty of tributes from dozens of worlds under their vassalage. Different administrations handled the balance of power in their own ways, some better than others. But one of the longest-running root causes for the Schism was the shifting of power away from the old Sangheili great houses, which increased the split between the Sangheili nobles (particularly those in the marches) and the Prophets.

The Shackling of the Faith

The Silent Oracle's apparent commands shocked the Covenant out of their Age of Doubt, and sparked a religious revival throughout much of the Holy Ecumene. The Hierarchs used these movements for their own political gain, and then turned upon them. Much that was new was deemed heretical, and even old traditions were closely examined and proscribed. The Hierarchs burned through a lot of capital trying to steer the faithful, and it earned them little but resentment and quiet rebellion.

The ascension of the Jiralhanae

It was no secret that the Prophet of Truth particularly favored the Jiralhanae and saw them as both a way of bringing new vigor to the Covenant, and a way to consolidate his (and the San'Shyuum's) power base. Truth subscribed to the Primalism school of thought, viewing the Jiralhanae as both more pure and easier to control than the Sangheili. The rapid ascension of the Jiralhanae was partly justified by the Prophets as the Sangheili wavering in their faith during the war, and was thus vastly accelerated by the war. Truth hardly even sought to become popular with the Sangheili as he put all his bets on the Jiralhanae. This led to many high-ranked Sangheili resenting him personally, and further polarized the relations between the Sangheili and the Jiralhanae empire-wide.

Truth wanted to be remembered as one of history's great Hierarchs, one who brought an end to a declining, bloated and quarrelsome noble class long past its prime, and reinvigorated the Covenant with new blood. His approach was in contrast to Regret's, who had hoped to use the Covenant War as a way to restore the Covenant's spiritual and political unity and make the Sangheili forget their petty squabbles, whether those be with High Charity, each other, or the newly-inducted Jiralhanae. A glorious holy war ushered in by a great Revelation could be a way for the members of the Covenant to set aside self-interest and focus on their common goal, as it had been in the Covenant's golden ages. And maybe Truth also believed this for a time, in those first years when the masses' zeal was at its highest.

The war also provided Truth with a convenient way to elevate the Jiralhanae with less outrage from the Sangheili than it otherwise may have caused. At the start, the elevation of the Jiralhanae was merely a contingency. Truth hoped that the Brutes, increasingly organized under the rising star Tartarus, could provide a check on the power of the Elites, and a way of finally dividing the once-exclusive warrior class more evenly. And so, as the war went on, Truth and his co-conspirators would funnel more and more resources to the Jiralhanae; worlds, ships, and industries, many of them located not only in the crossing regions between the human and Covenant spheres, but also in the Covenant empire proper. Even as this raised grumblings from the Sangheili Councilors, a bloc known as the Inquirers, Truth would merely wave them off as alarmists and point to the Sangheili regional nobles' sluggishness in mustering their own fleets for the war, or the rumblings of discontent by the warrior Compuncta and the radical Elenchist youth.

It is not conclusively known what Truth hoped to accomplish, but most suspect he did not initially plan the all-out genocide of the Sangheili. What Truth did, however, was plan on knocking them down for good, but he had underestimated the extent to which the Elites and Brutes (specifically those of Tartarus' coalition) wanted to get to each other's throats. He was not counting on the events cascading out of control as quickly or drastically as they did during the Great Schism, especially with the Flood and the humans getting involved. Regret's solo mission to Earth and subsequent assassination did provide Truth with the final excuse he had been looking for, but it also put him in something of a bind as he reasoned he had to act since an opportunity like it would probably not present itself anytime soon.

The War of Annihilation

The Human-Covenant War had no small role in sparking the Great Schism. Many civil wars of this scale and duration have been fought, so commentators often look for an underlying cause that made the war more disruptive than it should have been. The most obvious one is that wars of extermination are not common in the Covenant, nor are they celebrated in the annals of Covenant history. The Forerunners (the Librarian specifically) blessed all the sentient and sapient species active today as they might one day be able to join the Gods on the Great Journey, even though they were not yet ready at that point. Declaring an entire species Anathematics was not unheard of, but it was not common, and usually only occurred under very specific circumstances (e.g. the species having made themselves irredeemable abominations, such as one specific case of an ancient war against a post-biological machine race). But to many Covenant warriors, humans did not fulfill such criteria, and even though they did sin, so had many of the Covenant species once before being shown the Path, most pointedly the Lekgolo. And many showed courage and other traits the Sangheili admired, not to mention the fact an all-out genocide was an overall troubling and nearly alien notion to those brought up in the Covenant's later ages. Enemies of the Journey should be opposed and fought, but they should also be made to see the error of their ways and brought into the Covenant fold. To exterminate a species meant a failure of the Covenant's overarching mission of Universal Conversion.

And while the war dragged out far longer than Truth or Regret had hoped or planned, these grumblings of discontent grew louder and eventually reached the High Council itself. The war was unpopular, not just among the Sangheili but also many of the lower-ranked species as well as many within the Holy Ecumene's religious circles, such as holy orders and theological groups including the Ascetics and the Rennai. Consequently Truth and Regret were forced to scrape the bottom of the barrel for their forces in many cases, including the use of borderline feral penal legions and dishonored Executioner shock troops to carry out the "dirty work" of the genocide the Sangheili were usually too proud or troubled to engage in directly. But this, too, served to strengthen the Jiralhanae's position, as many members of Tartarus' coalition were both eager to prove their worth and less culturally or religiously squeamish about genocide. In turn, this made Truth more and more convinced of the new species' superiority as the Sangheili's replacements.

Political upheavals

The Shuffling of the Ministries: Truth and Regret made many changes to the way the Ministries functioned. Although the changes seemed small and necessary at first, the cumulative effect strengthened central power and upset many old agreements that had kept the peace. Eventually the newly-empowered Ministries encroached upon the High Council's territory. By the time anyone on High Charity took notice of the new status quo, the Ministries were already running rampant.

• Tax reforms and increased ministerial encroachment that alienated the guilds + generally indicative of rise of merchant class
• Disharmony between the Hierarchs, especially Truth and Regret who often worked toward their own goals which they did not share with the other, even as they were occasionally forced to cooperate.
• Various backroom dealings
• Truth and Regret's populism and nonspecificity pissed off HC's religious elite and many nobles; Mercy was trying to mend this and shore up Covenant theology for a major upheaval.

Immediate causes

What is usually cited as the point of no return for setting the Great Schism in motion is when the Prophet of Regret's Fleet of Sacred Consecration stormed Earth. Upon finding the Sol system teeming with humans, Regret could still have withdrawn into slipspace, returned to High Charity and reported his findings. But he did not, and everything degenerated from there. Regret jumped to Delta Halo, and somehow made a bad situation even worse. Truth had known Earth's location for some time and was planning to act eventually, but he was biding his time. After the destruction of the grand fleet he had been assembling at the Unyielding Hierophant, he may have still waited for months before crushing Earth. He may have waited for the uproar from the destruction of the first Sacred Ring to die down sufficiently and for the Covenant to consolidate. But Regret forced him to accelerate his plans, which is where things also went downhill for Truth.

The Great Schism

Changing of the Guard

• Sangheili threatening to resign from the High Council may've happened before — an extreme but known political statement that signified major outrage but had never been followed up on.
• Backroom dealings with Truth and loyalists + Tartarus; how much was planned, how deep the conspiracy went, and how much was just things escalating.
• Recovery of the Sacred Icon & Tartarus' betrayal

Truth's ultimatum

The position of the high-ranking San'Shyuum in Truth's plan was also complicated, for not all Prophets involved with the plan were even aware of its full extent. Even as they were given new postings as advisors to Brute fleetmasters and chieftains they could only guess at the reasons. Only when the Schism began to unfold they were sent secret missives from Truth himself, informing them of what was about to take place and what their own role in it would be. Many San'Shyuum chose not to follow these orders despite Truth threatening them with immediate excommunication for siding with the Sangheili. Others disowned Truth later on as the war began to turn in the Sangheili's favor.

War in High Charity

The Covenant's most holy city became a battleground in the first day of the Schism.

• First shots
• Master Chief & Cortana
• The Flood & Truth leaving High Charity
• Uprising on Delta Halo + truce at the control room, news of the truce (not yet too widespread) and subsequent events - capture of the Pious Inquisitor (+negotiations aboard) and the race to Earth
• Formation of the Fleet of Retribution, Fleet of Deliverance, and the Fleet of Defiance, quarantine of Installation 05
• NAWW events & Minister of the Common Weal - involvement with overall truce / pact? Follow up on this

Summons at Joyous Exultation

Historians often comment that the death of Xytan Jar 'Wattinree and the destruction of the Combined Fleet of Righteous Purpose not only evened out the scales between the Sangheili and the Jiralhanae, especially in that region, and also partly allowed Concord to rise and a lasting alliance with humanity to happen. Xytan would not have shared power and while no one can know what he would have done with humans, whether he would have continued the war or reduced humanity into a protectorate, he was known for both his zeal and ambition.

Race to the Ark

Earth and the Ark + further negotiations and truce + concurrent events at High Charity and Holy Ecumene

The War of Wrath

The devastation of Joyous Exultation and much of the Sangheili leadership gathered there opened the way for the Brutes to spill into the coreside spinward territories relatively unhindered, and take over multiple strongholds there in the final months of 2552. Many of the Chieftains in charge of these strongholds effectively declared them their own fiefdoms as the war went on. In the coming years they would be opposed by the Fleet of Defiance under Fleetmaster Nerit 'Mulaparthan.

• Singular Bond, Operation: FORTRESS SIEGE and Soell's recapture
• Campaigns in the crossing channels; Pleiades Corridor, Muruga Skip, Orion-Eridanus Region, Tempest Crossing, Zhoist and other resource/industrial worlds
• Major splits, like the Keepers of the One Freedom
• Torchbearer Soell invasion in 2555, attempted Excession invasion in 2559 (intercepted early); Zhoist retaken from Brutes in 2559
• Position of armadas and various worldships
• The Concord of Reconciliation, the Strewn Shore and Schismatic-aligned San'Shyuum
• UNSC operation(s) going past human space - Operation: ICARUS, etc; expeditionary group(s); in stages. Manifold goals; political and also learning more about Brute/Covenant space, and of course strategic ones; getting rid of the most acute threat to their existence. Also, Concord aid may be partly reliant on this continued military integration (goal to prevent future wars by making both sides familiar with each other + making wars non-feasible).

Without Truth or Tartarus the Jiralhanae forces began to grow increasingly uncoordinated as time went on. The Jiralhanae lacked strong leaders with enough vision to keep the tribal nations unified; while some arose, they soon fell or were not strong enough without Truth's support.

As the tide began to turn, some of the San'Shyuum legates assigned to the forces also began to waver in their loyalties to Truth, and sought to steer the Jiralhanae to pursue more diplomatic solutions; though others remained hawkish. Following the Pact at Unkarath, some fleets were suspected to have fled far beyond the Holy Ecumene's borders, to the spinward side of the Orion Arm or far coreward of the Inner Corelight Reefs, perhaps as far as the Sagittarius Arm.

Cultural and religious impact

The Schism Councils

Main article: Schism Councils