Editing Human-Covenant War

{{Status|Canon}}
{{Battle infobox
|name=Human-Covenant War 
|prev=[[Insurrection]] {{c|original conflict}}
|conc=*[[Insurrection#During the Human-Covenant War|Insurrection]] {{c|in reduced capacity}}
*[[Great Schism]]
|next=*[[Post-Covenant War conflicts]]
**[[Blooding Years]]
**[[Insurrection#Post-war resurgence|Insurrection]] {{c|postwar resurgence}}
**[[Sangheili-Jiralhanae war]]
|image=[[File:Other Wiki HCW collage.png|415px]]<br>Clockwise from top left: [[Insurrectionist]]s are attacked by the Covenant at [[Alpha Corvi II]]; UNSC forces under fire inside a [[Relic (location)|Relic]] on [[Harvest]]; a {{Class|CAS|assault carrier}} [[glassing]] [[Kholo]]; [[John-117]] on a [[Pelican]] over [[Installation 04]]; [[Sangheili Honor Guardsman|Sangheili Honor Guardsmen]] fighting [[Jiralhanae]] at the start of the [[Great Schism]]; [[Arbiter]] [[Thel 'Vadam]], John-117, Sergeant [[Avery Johnson]], and [[343 Guilty Spark]] on [[Installation 08]]
|date=[[2525|February 11, 2525]]<ref>[[First Battle of Harvest]]</ref>–[[2552#December|December 11, 2552]]<ref>[[Halo 3]]</ref>
*[[2553#March|March 3, 2553]] <small>([[Voi Memorial|official ceremony]])</small>
|place=The [[Orion Arm]] of the [[Milky Way]]<ref group="notes">The Human-Covenant War briefly extended outside the Milky Way galaxy for the [[Battle of Installation 00]]</ref>
|result='''Human-Sangheili victory'''<ref>''[[Believe]]'', [[Museum]]</ref> 
*Covenant Empire collapses<ref name="The Covenant">''Halo 3'', campaign level, [[The Covenant (level)|The Covenant]]</ref>
*[[Flood]] threats sterilized and contained{{Ref/Reuse|The Covenant}}
*Activation of the [[Halo Array]] averted<ref>'''[[Halo: Glasslands]]''', ''page 50''</ref>
*Human and [[Fleet of Retribution|many]] Sangheili forces [[Treaty of 2552|reconcile]]<ref name="Halo">''Halo 3'', campaign level, [[Halo (Halo 3 level)|Halo]]</ref><ref>''Halo: Glasslands'', p. 60</ref>
*[[Sangheili-Jiralhanae war|Ongoing conflict between former Covenant factions]]<ref>''Halo: Evolutions - Essential Tales of the Halo Universe'', "[[The Return]]"</ref>
|side1=*{{Icon|UNSC HCW}} '''[[United Nations Space Command]]'''
*{{Icon|Covenant FB}} '''[[Covenant separatists]]''' {{C|From [[2552#November|November 3, 2552]] onwards}}
**'''[[Fleet of Retribution]]''' 
----
*{{Icon|Insurrectionist}} '''[[Insurrectionists]]'''
**'''[[United Rebel Front]]'''
|side2=*{{Icon|Covenant FB}} '''[[Covenant]]'''
|side3=*'''[[Flood]]'''
|side4=*{{Icon|Forerunner}} '''[[Sentinel|Forerunner constructs]]'''<ref group="notes">'''Allied''' with UNSC/Fleet of Retribution '''only''' during the 1st half of the Battle of Installation 04 (UNSC only), Battle of Installation 05 and Battle of the Ark. Elsewhere and excluding these battles, Forerunner constructs were '''hostile''' to the UNSC/Fleet of Retribution' (including during the 2nd half of the Battle of installation 04 (UNSC only), Battle of the Etran Harborage (UNSC only), Battle of Onyx (UNSC only) and the Raid on Installation 08). However, Forerunner constructs were '''hostile''' to both Flood and Covenant forces throughout the entire war.</ref>
|commanders1=
[[UNSC High Command|High Command]]
*[[Fleet Admiral|FADM]] [[Terrence Hood|Lord Terrence Hood]]
*[[Admiral|ADM]] [[Preston Cole]]† (MIA, assumed KIA)
*[[Admiral|ADM]] [[Margaret Parangosky]]
*[[Admiral|ADM]] [[Michael Stanforth]]†
*[[Admiral|ADM]] [[Danforth Whitcomb]]†
[[Fleet of Retribution]]
*[[Arbiter]] [[Thel 'Vadam]]
*[[Shipmaster]] / [[Fleetmaster]] [[Rtas 'Vadum]]
----
[[Insurrectionists]]
*[[Governor]] [[Jacob Jiles]]†
|commanders2=
[[Hierarchs|High Prophets of the Covenant]]†
*[[Prophet of Truth|High Prophet of Truth]]†
*[[Prophet of Regret|High Prophet of Regret]]†
*[[Prophet of Mercy|High Prophet of Mercy]]†
[[High Council|Covenant High Council]]<br>
Military commanders
*[[Chieftain of the Jiralhanae]] [[Tartarus]]†
*[[Fleetmaster]] [[Nizat 'Kvarosee]]
*[[Special Operations Commander]] [[Rtas 'Vadum]]ee {{c|pre-Great Schism}}
*[[Arbiter]] [[Ripa 'Moramee]]†
*[[Fleetmaster]] [[Voro Nar 'Mantakree]]† {{c|pre-Great Schism}}
*[[Imperial Admiral]] [[Xytan 'Jar Wattinree]]† {{c|pre-Great Schism}}
*[[Supreme Commander]] [[Thel 'Vadam]]ee {{c|pre-Great Schism}}
|commanders3=[[Gravemind]]†
|commanders4=
[[Sentinel|Forerunner constructs]]
*[[343 Guilty Spark]] {{C|[[Wounded in action|WIA]]}}
|forces1=
|forces2=
|forces3=
|forces4=
|casual1=
;Human population reduced considerably
*Approximately 23 billion civilian and military casualties by October 20, 2552;<ref name=HE:PH>'''[[Halo: Evolutions - Essential Tales of the Halo Universe|Halo: Evolutions]]''', "[[Palace Hotel]]", ''page 351''</ref> billions more during the [[Battle for Earth]]<ref>'''Halo: Glasslands'''. ''page 151''</ref>
*Widespread infrastructure, structural, and environmental damage to the vast majority of UEG colonies
;Heavy Sangheili casualties
*Devastation of the Sangheili colony, [[Joyous Exultation]].
*Destruction of the Sangheili colony, [[Glyke]]
*Billions of civilian casualties
----
;Heavy Insurrectionist casualties
*All [[Eridanus Rebels]] killed
*Moderate Rubble rebel casualties
*[[Outer Colonies]] [[Massacre of the Outer Colonies|decimated]]
|casual2=
;Heavy casualties for all Covenant races
*Destruction of the Covenant holy city, ''[[High Charity]]''
*Destruction of the Covenant battle station ''[[Unyielding Hierophant]]''.
*Near-extinction of the ruling San'Shyuum 
|casual3=
;Extreme casualties for the Flood
*High Charity destroyed  
*Installation 05 sterilized
*All Flood forces destroyed at the Etran Harborage, Installation 04 and Installation 08
|casual4=
; Heavy casualties for Forerunner constructs
*Destruction of [[Installation 04]] and its replacement [[Installation 08]]
*Glassing of [[Installation 05]]
*Devastation of [[Installation 00]]
}}
{{Series/War/Human-Covenant War}}
{{Quote|Your destruction is the will of the Gods... and we are their instrument.|The Covenant's declaration of war.<ref>''Halo: The Fall of Reach'', p. 98 (2001)</ref>}}

The '''Human-Covenant War''',<ref>'''Halo: The Fall of Reach (2001)''', ''back cover description''</ref><ref>'''Halo: The Flood (2001)''', ''back cover description''</ref> also known as the '''Covenant War''',<ref>'''[[Halo: The Essential Visual Guide]]''', ''pages 19, 74, 75, 92, 95, 98, 105, 112, 113, 120''</ref><ref>'''Halo Waypoint''': [http://halo.xbox.com/en-us/intel/featured/video/headhunters-1/c3d2dcb3-ac3d-4771-a270-e55e33ae118b ''Headhunters'' Part 1], [http://halo.xbox.com/en-us/intel/featured/video/herocourage/c2ada678-e9ce-4db9-9ce9-1864070bd198 ''Hero - Courage'']</ref><ref name="title" group="notes">The name "Covenant War" is most often used by media from [[343 Industries]]. However, the less common "Human-Covenant War" is more descriptive and is therefore used by ''Halopedia''.</ref> the '''Great War''',<ref>''Halo: First Strike'' (2010), [[Petra]]</ref> and the '''War of Annihilation''' by the [[Covenant]],{{Ref/Novel|SoR|Chapter=3}}{{Ref/Novel|DW|Chapter=1}}{{Ref/Book|Enc22|Page=193}}{{Ref/Site|URL=https://www.halowaypoint.com/news/the-new-halo-encyclopedia-is-out-today|Site=Halo Waypoint|Page=The New Halo Encyclopedia is Out Today|D=11|M=03|Y=2023}} was a major interstellar conflict pitting [[humanity]] and its [[United Nations Space Command]] against the Covenant during the mid-26th century between [[2525#February|February 11, 2525]] and [[2552#December|December 11, 2552]]. There were two additional factions sporadically involved in the conflict: the [[Flood]] and a small number of surviving [[Sentinel|Forerunner constructs]]. Both factions proved to be invaluable to the efforts of humanity, as the information taken from Forerunner constructs and the Flood invasion of ''[[High Charity]]'' were helpful in [[Great Schism|splitting the Covenant apart]] in November 2552.

The war was instigated by the [[Hierarchs|High Prophets]] of the Covenant following a discovery which led them to believe that humans were directly related to the Forerunners, contradicting their [[covenant religion|ancient religion]]. Seeking to keep various political and religious orders intact, the High Prophets declared a holy war of genocide against the human species, and the discovery of their relation to the Forerunners was kept a secret.  With superior firepower, numbers and technology, the Covenant would repeatedly overpower the UNSC across hundreds of human-inhabited worlds, including the heavily defended strongholds of [[Reach]] and [[Earth]]. Humanity would win only scattered and costly victories.

The conflict was also the cause of the [[Great Schism]] within the Covenant. Forced to fight a war on two fronts, the formerly monolithic empire was torn apart. The [[Battle of Installation 00|final battles]] of the war were fought on [[2552#December|December 11, 2552]], ending the Covenant,<ref name="fortitude">[http://halo.xbox.com/en-us/intel/featured/video/herofortitude/bfe5038b-314a-4f17-a6be-f7613e0e3788 '''Halo Waypoint''', ''Hero-Fortitude'']</ref> and the ceasefire between humanity and the Sangheili was formally ratified as a [[Treaty of 2552|treaty]] on [[2553#February|February 2553]].<ref name="ceasefire">'''Halo: Glasslands''', ''pages 358-361''</ref> The official end of war [[Voi Memorial|ceremony]] took place on [[2553#March|March 3, 2553]]. The war was incredibly costly to both sides, with over twenty-three billion humans and billions of Covenant individuals killed during the hostilities.<ref name=HE:PH/> An outbreak of the virulent parasite known as the Flood almost consumed both factions near the war's end. The conflict lasted for a total of twenty-eight years.

After the [[Treaty of 2552|ceasefire]] was declared, the Great Schism continued in the form of [[Sangheili-Jiralhanae war|wars]] between the Sangheili and the Jiralhanae until at least [[2559]].<ref>'''Halo: Evolutions''', ''The Return''</ref> Concurrent to this, the Sangheili species fell into [[Blooding Years|civil war]], as did the Jiralhanae, while the UNSC itself had to deal with a resurgence in the [[Insurrection]]. In the wake of the Covenant's cessation, its former member species fragmented and formed many new [[Covenant remnants|splinter factions]]. Among the most notable of these smaller groups was the religiously devout [[Jul 'Mdama's Covenant faction|new “Covenant”]] formed in the disarray following the war by [[Shipmaster]] [[Jul 'Mdama]]. The UNSC occasionally engaged in [[Post-Covenant War conflicts|smaller conflicts]] with Jul's faction and a few others, until late [[2558]].<ref name="Spops">[[Halo 4]] [[Spartan Ops]], level [[Departure]]</ref>

==Background==
===Insurrection===
{{Main|Insurrection}}
{{Expand-section}}

==War==
[[File:SSgt Avery Johnson, UNSC Marine Corps.JPG|thumb|right|200px|Staff Sergeant Johnson leading Colonial Militia during the Covenant invasion of Harvest.|left]]
===Isolated battles (2525)===
{{Main|First Battle of Harvest}}
Humanity and the Covenant first came into direct contact on February 3, 2525, when a [[Kig-Yar]] [[missionary ship]], the ''[[Minor Transgression]]'', discovered [[Horn of Plenty|a human ship]] transitioning out of [[Slipstream space|slipspace]] and subsequently raided the vessel.<ref>''Halo: Contact Harvest'', p. 27</ref> The raid continued to [[This End Up|another]] unfortunate human ship.<ref>''Halo: Contact Harvest'', p. 97-100</ref> Some time after, [[Sif]], Harvest shipping operations AI, investigated the raids and reported her findings to an undercover [[Office of Naval Intelligence]] agent, [[Jilan al-Cygni]], believing that the attacks were Insurrectionist activity. The ONI agent devised a trap for the raiding parties, which resulted in a [[Skirmish Over Harvest|minor skirmish]] between [[Staff Sergeant]]s [[Nolan Byrne]] and [[Avery Johnson]], and the Kig-Yar privateers.<ref>''Halo: Contact Harvest'', p. 128-134</ref> When the Covenant returned with [[Rapid Conversion|another ship]] and a contingent of [[Jiralhanae]] and [[Yanme'e]], the UNSC proposed a meeting (via pictogram) with the intention to make amends and to trade with the alien species.<ref>''Halo: Contact Harvest'', p. 229</ref> The Covenant met the UNSC on Harvest, but were only interested in claiming the relics that the [[Luminary]] had detected on Harvest, completely oblivious that the humans were the "relics" in question. The meeting was botched after [[Osmo]], a member of the [[Harvest militia|Colonial Militia]], was attacked by a nervous [[Unggoy]] who was part of a second Covenant force sent to look for the relics. As a result, a firefight erupted between the two groups and the Covenant promptly retreated back to their ship.<ref>''Halo: Contact Harvest'', p. 213</ref>

The political ramifications of these relics were abundant, and two [[San'Shyuum]] bureaucrats, the [[Prophet of Truth|Minister of Fortitude]] and the [[Prophet of Regret|Vice Minister of Tranquility]], were already scheming to use the supposed reliquary to inaugurate a new [[Ages of Reclamation|Age of Reclamation]] with themselves as the [[Hierarchs]] of the [[High Council]].<ref>''Halo: Contact Harvest'', p. 271</ref> To do this, they needed the blessing of the Oracle of [[High Charity]]. When the two San'Shyuum approached the [[Prophet of Mercy|Philologist]] to affirm on their behalf, the data from the ''Rapid Conversion'' caused [[Mendicant Bias|the long-dormant Oracle]] to reactivate. Mendicant declared that the Covenant had been misinterpreting Forerunner symbols: the "relics" in question were the humans, calling them [[Reclaimer]]s and his makers. This shocked the three San'Shyuum, who falsely concluded that the humans were actually living [[Forerunner]]s who had been left behind when the others transcended.<ref>''Halo: Contact Harvest'', p. 275 ("'The Forerunners,' the Minister whispered. 'Some were left behind.'")</ref> Although they were able to prevent Mendicant from taking the [[Forerunner Dreadnought]] to take the humans to deliver them to [[Installation 00|the Ark]], Fortitude concluded that if the masses learned that they might be left behind, they would rebel against the Prophets. Fortitude and Tranquility inducted the Philologist into their plan and ascended as the High Prophets of Truth, Regret, and Mercy. 

===Open war (2525-2535)===
[[File:HWG SecondBattleOfHarvest.png|thumb|250px|Cole's fleet destroys the Covenant ship in the Second Battle of Harvest.|left]]
{{Main|Massacre of the Outer Colonies}}
Intending to keep the revelation about the humans a secret and prevent the Covenant from falling apart, the new Hierarchs declared that the humans destroyed the holy reliquary on Harvest, and ordered the entire race to be eradicated.<ref>''Halo: Contact Harvest'', p. 384</ref> The first battle of the war was the extended, albeit one-sided, engagement which took place on Harvest where the UNSC managed to evacuate many of Harvest's civilians.<ref>''Halo: Contact Harvest'', p. 352</ref> Eventually, the Covenant ship responsible for the attack [[Glassing|glassed]] the planet's surface.<ref>''Halo: Contact Harvest'', p. 387</ref>

Realizing the threat posed to humanity by the Covenant, the UNSC [[Colonial Military Authority]] gave [[Vice Admiral]] [[Preston Cole]] the command of the then-largest fleet in human history with orders to [[Second Battle of Harvest|retake Harvest]],<ref name="Genesis">'''[[Halo Wars: Genesis]]''', pages 1-10</ref> which occurred in [[2526]].<ref>'''Halo: Evolutions''', ''The Impossible Life and the Possible Death of Preston J. Cole'', pages 462-467</ref> H would then spend five years chasing the Covenant around the [[Outer Colonies]], fighting them and scoring victories at [[Alpha Aurigae System|Alpha Aurigae]], [[XI Boötis A System|XI Boötis A]], and [[Groombridge-1830]].{{Ref/Reuse|Genesis}}<ref name="battles">'''Halo: Evolutions''', ''The Impossible Life and the Possible Death of Preston J. Cole'', page 470</ref> Meanwhile, the Covenant returned to Harvest, determined to recapture the planet. This led to a five-year long [[Harvest Campaign|series of engagements]] on Harvest between the Covenant and the UNSC.<ref>'''[[Halo: The Essential Visual Guide]]''', ''page 188''</ref> Because of the threat the Covenant posed, the UNSC began deploying the [[SPARTAN-II Program|SPARTAN-II]]s on November 2nd, 2525,{{Ref/Novel|Id=hsschapter2|HSS|Chapter=2}} super soldiers originally trained to fight the [[Insurrection]]. The Spartans became one of humanity's greatest — and most celebrated — defenders, demonstrating a remarkable ability to turn the tide of battle. Their prowess was not lost on the Covenant, who came to fear the Spartans as "[[demon]]s".<ref>'''[[Halo: The Fall of Reach]]''', ''page 103''</ref>

From that point on, the Covenant continued to attack and destroy the humans wherever they were found, using their [[Luminary|Luminaries]] to find human worlds. Though the UNSC forces fought bravely, their inferior technology and numbers meant that even a ''close'' victory was far from guaranteed. The Covenant, fighting a war of extermination, did not need to commit to full ground invasions except in special circumstances; their ships simply needed to destroy space-borne defenses and any other threats around the planet. They would then reduce the planet's surface to glass with orbital plasma bombardment.<ref>''[[Halo Encyclopedia (2009 edition)]]'', Chapter 1, p. 33</ref> In general, human missiles and magnetic acceleration weapons were asymmetrically matched with Covenant energy shields and plasma weaponry. The few major victories achieved by the UNSC were usually due to tactical genius, extensive use of nuclear weapons, the rapid deployment of Spartan teams, or decisive ground engagements where UNSC technology and skill outmatched Covenant tactics. At the outset of the war, the UNSC employed a [[Wikipedia:defence in depth|defence in depth]] tactical doctrine, making extensive use of [[M5 Talos|automated turrets]] to delay Covenant forces.<ref name="PL Turret">''Halo Wars 2'', [[Phoenix Logs]] - Turret</ref> They were eventually forced to abandon this doctrine as the war continued to grind down human armies and industrial centres{{Ref/Reuse|PL Turret}}, learning the dangers of relying on fixed installations when employed against enemies with orbital fire support.<ref name="PL Siege">''Halo Wars 2'', [[Phoenix Logs]] - Siege Turret</ref> The UNSC began to develop a modular [[firebase]] system (based on pre-existing [[colony starter unit]]s used for colonization of planets<ref>[http://www.halowars.com/GameInfo/UNSC.aspx ''Official Halo Wars Community Site'': UNSC] (defunct, [[Archive:Halowars.com/UNSC|Archived]])</ref>) in response to pinpoint Covenant targeting of large military command and control installations with orbital strikes, and the inability of standard counter battery systems to detect, deflect, or defeat plasma-based artillery bombardment.<ref name="PL Siege"/>

Despite the well-publicized victory at Harvest, the UNSC was already on the way to losing the war. A number of colonies had already been glassed by the Covenant or abandoned, including [[Eridanus II]], [[Dwarka]], [[Bliss]], [[Madrigal]], [[Asmara]] and [[Biko]].

=====Trove and SPARTAN-III (2531)=====
Despite their major numerical and technological advantages over humanity, by [[2531]], the Covenant High Prophets had realized that the task of destroying an entire sapient species had a logistical burden beyond anything that the [[Covenant military]] could muster without leaving Covenant space defenseless.<ref name="HWscarab">'''[[Halo Wars]]''', campaign level ''[[Scarab (Level)|Scarab]]''</ref> Seeking a more efficient solution, the [[Prophet of Regret]] dispatched [[Arbiter]] [[Ripa 'Moramee]] to Harvest to claim a Forerunner [[Relic (location)|artifact]] buried under the north pole of Harvest.<ref>'''Halo Wars''', campaign level, ''[[Alpha Base (Halo Wars level)|Alpha Base]]''</ref> After a heated fight on the surface, forces from the UNSC ''Spirit of Fire'' were able to examine the artifact, a star map, and realized that it had led the Covenant to another human colony: [[Arcadia]].<ref name="city">'''[[Halo Wars]]''', campaign level, ''[[Arcadia City]]''</ref>

[[File:ApexBattleImage.png|thumb|200px|The {{UNSCShip|Spirit of Fire}} engages the {{Pattern|Sinaris|heavy destroyer}} ''[[Proclamation's Tithe]]'' in [[Trove]].]]

As predicted, the Covenant [[Battle for Arcadia|followed the information]] from the artifact to Arcadia. The Covenant hoped that the planet would contain more Forerunner artifacts for them to claim, and while they only found a [[Arcadia Forerunner ruins|complex of ruins]], information garnered from them led them to a [[Trove|Shield World]]. The ''Spirit of Fire'' followed and removed the Covenant presence from the planet. However, 'Moramee's capture of an [[Ellen Anders|important civilian researcher]] forced Captain Cutter to pursue the Covenant to the newly discovered Shield World without reinforcements.{{Ref/Reuse|HWscarab}}

On the Shield World, the crew of the ''Spirit of Fire'' eventually discovered that the Covenant needed Professor Anders to activate [[the Apex]] and claim the huge fleet of [[Sojourner-class dreadnought|Forerunner dreadnoughts]] held there.<ref>'''Halo Wars''', campaign level, ''[[Beachhead (Halo Wars level)|Beachhead]]''</ref> A group of Marines, together with SPARTAN-II [[Red Team]], rescued the researcher and destroyed the Shield World by initiating the collapse of the interior star. The Arbiter was also killed by [[John Forge]] during the battle though the Prophet of Regret escaped.<ref>'''Halo Wars''', campaign level, ''[[Escape (Halo Wars level)|Escape]]''</ref>

The UNSC's sole hope apparently lay with the SPARTAN-II Program. However, there were never enough Spartans to decisively turn the tide of the war in favor of humanity. Recognizing this, the [[Office of Naval Intelligence]] authorized the creation of the [[SPARTAN-III Program]]. The brainchild of [[Colonel]] [[James Ackerson]], these Spartans would be trained with a greater emphasis on stealth and teamwork, and would be sent on missions against high-priority targets that would be impossible even for elite units.<ref>''Halo: Ghosts of Onyx'', p. 43-46</ref>

=====Crisis (2532-2535)=====
[[File:CP armor.png|thumb|left|200px|A member of Gray Team at the [[Battle of the Rubble]].]]
After just six years of combat, space battles with the Covenant had depleted the UNSC's nuclear stockpile to almost nothing in some sectors of space.<ref>'''[[Halo: Ghosts of Onyx]]''', ''page 34''</ref>

With the majority of the Outer Colonies glassed or abandoned, the UNSC faced an economic crisis, as many of their [[agriculture world]]s had been destroyed, leading to food shortages. On [[Charybdis IX]], food riots were common.<ref>''Halo: The Cole Protocol'', p. 106</ref> Meanwhile, Covenant forces began to encroach on the [[Inner Colonies]].<ref>''Halo: The Cole Protocol'', p. 25</ref> In response, the UNSC issued [[United Nations Space Command Emergency Priority Order 098831A-1]], otherwise known as the "Cole Protocol". It stated that no UNSC vessel may lead the Covenant to Earth or any other human population center. Furthermore, all movement through space was restricted to [[UNSC Navy]] vessels.{{Ref/Reuse|Genesis}} [[Insurrectionist]] attacks increased in the face of what the colonies perceived as a removal of their right to freedom of movement. This was to culminate in the discovery of Insurrectionists using Covenant weapons supplied by apparently renegade [[Kig-Yar]]. Shocked, the UNSC viewed this as a major threat to security.<ref>''Halo: The Cole Protocol'', p, 109</ref> Upon learning of this, the [[Prophet of Regret]] declared such weapons as heresy, and as a result dispatched [[Thel 'Vadam]]ee to destroy the source of the modified weapons: a remote asteroid habitat known as [[the Rubble]].<ref>''Halo: The Cole Protocol'', p. 146</ref>

Fleeing from the [[Battle of Charybdis IX]], the {{UNSCShip|Midsummer Night}} chased an Insurrectionist freighter to the Rubble and discovered that the Insurrectionists there had actually formed an alliance with a group of Kig-Yar.<ref>''Halo: The Cole Protocol'', p. 176</ref> The Jackals were supplying the weapons and the Insurrectionists were modifying them. The crew of the ''Midsummer Night'', including its captain, [[Lieutenant]] [[Jacob Keyes]], were captured, but later escaped and helped SPARTAN-II [[Gray Team]] and the Rubble's citizens stop an assault from the Kig-Yar leader, [[Reth]], and 'Vadamee's forces. They managed to rescue a million civilians from behind enemy lines and escorted them to [[Falaknuma]].<ref>''Halo: The Cole Protocol'', p. 352</ref>  It later transpired that the [[Prophet of Truth]] had ordered the Kig-Yar to ally with the humans so that they could discover the location of [[Earth]] from stolen navigation data or through tracking devices in the weapons. Through this, the Covenant found two more worlds to attack.<ref>''Halo: The Cole Protocol'', p. 347</ref>

By the time of the [[Battle of Jericho VII]] in 2535, most of the Outer Colonies were either destroyed, or cut communications with the UNSC.

===Inner Colony push (2536-2551)===
{{Main|Siege of the Inner Colonies}}
[[File:Origins ii Human-CovenantWar.jpg|thumb|225px|Humanity, heavily out-gunned, lost much ground to the Covenant.]]
For fifteen years, the war ground on in a predictable pattern; costly and rare victories on the ground for UNSC forces, with near total Covenant space superiority.{{Ref/Book|Enc11|Page=205}} The UNSC managed to deal a heavy blow to the Covenant in 2537 with the destruction of the Covenant manufacturing plant [[K7-49]] in [[Operation: PROMETHEUS]],<ref>''Halo: Ghosts of Onyx'', p. 341</ref> and again during the [[Siege of the Atlas Moons]] in the same year. However, these victories were offset by the loss of [[New Constantinople]], the loss of its colonies at [[Leonis Minoris]], and the total destruction of the force of SPARTAN-IIIs sent to destroy the Covenant base.<ref>''[[Halo: First Strike]]'', p. 179 ("John had never worked with the Admiral before, but his accomplishments during the battles for New Constantinople and the Siege of the Atlas Moons were well known.")</ref>

Throughout the 2540s, the UNSC was dealt ever greater blows with the death of the SPARTAN-II [[Sheila-065]] during the [[Battle of Miridem]] in 2544,<ref>'''Halo: Ghosts of Onyx''', ''page 173''</ref> followed by the [[Battle of Actium|defeat at Actium]] in [[2545]],<ref>[http://halo.xbox.com/en-us/intel/featured/video/herocourage/c2ada678-e9ce-4db9-9ce9-1864070bd198 '''Halo Waypoint''' video, ''Hero-Courage'']</ref> defeat during the [[Fall of Arcadia]]<ref>'''[[Dr. Halsey's personal journal]]'''</ref> and the [[Siege of Paris IV|loss of Paris IV]] in 2549.<ref>''Halo: First Strike'', p. 244</ref> One of the UNSC's success was [[Operation: TORPEDO]] in 2545. The loss of 298 SPARTAN-IIIs was ultimately considered acceptable losses by UNSC High Command.<ref name=Onyx27 >''Halo: Ghosts of Onyx'', p. 21</ref> The SPARTAN-II raid on the [[Third Fleet of Glorious Consequence]] to recover a captive Dr. Halsey further proved the Covenant Empire was overwhelmingly powerful, but not invincible.<ref>'''[[Halo Legends]]''', ''[[The Package (animated short)|The Package]]''</ref>

Of the few major wins in the 2540's for the UNSC, and one of the most significant and strategically advantageous was the [[Battle of Psi Serpentis]] in 2543. This engagement became colloquially known as Admiral Cole's last stand due to the presumed death of [[Preston Jeremiah Cole|Admiral Preston J. Cole]]. In addition to the alleged death of Cole, over 300 [[Covenant Empire|Covenant]] vessels, two fleets worth, were completely vaporized when [[UNSC]] [[Nuclear weapon|nuclear missiles]] detonated inside the atmosphere of [[Viperidae]], a supermassive gas giant. This detonation spurred spontaneous fusion at the core of Viperidae, temporarily turning the super gas giant into a brown dwarf star.<ref name="Psi Serpentis">''Halo: Evolutions'', "The Impossible Life and the Possible Death of Preston J. Cole", p. 476-482</ref> Cole's achievements in this battle alone were only rivaled by the [[Operation: FIRST STRIKE|destruction]] of the ''[[Unyielding Hierophant]]'' and the actions of [[John-117|Spartan-117]] throughout the course of the war.{{Ref/Reuse|Alamo}}

[[File:Covenant assault - 2.png|thumb|left|225px|[[Civilian]]s on a human colony world under siege by a Covenant invasion force.]]
While the Covenant had merely been slowed by the UNSC's military efforts, there was growing tension between the [[San'Shyuum]] and the [[Sangheili]] over the Human-Covenant War. At first, the Sangheili had followed the Prophets command to destroy the humans without question. But after more than twenty five years of war, humanity's continued and fierce resistance in the face of certain death had deeply impressed the martial Sangheili.<ref>''Halo: The Cole Protocol'', p. 139</ref> There was a growing consensus among the Sangheili that the humans had earned the right to be offered membership in the Covenant, which the Prophets continued to reject. At the same time, the [[Jiralhanae]], the one race which could challenge the Sangheili's dominance of the Covenant military, were rapidly earning favor with the Prophets, as they were less inclined to question orders.<ref>'''[[Conversations from the Universe]]'''</ref> In fact, even the Prophet of Clarity [[Zo Resken]] began to secretly question why humanity wasn't offered a place in the Covenant.{{Ref/Novel|BC|Chapter=15}}

Towards the end of the war in 2552, the Office of Naval Intelligence was resigned to the fact that humanity may only have months left before the Covenant destroyed the remaining Inner Colonies and moved against Earth. To try and buy time, HIGHCOM ordered all available SPARTAN-IIs to return to Reach and commence [[Operation: RED FLAG]], a mission to locate the Covenant homeworld and capture a Prophet to force the Covenant into a cease-fire.<ref>''Halo: The Fall of Reach'', p. 240-245</ref>

===The final year (2552)===
The last year of the war saw humanity's largest defeat since the war's beginning, but also saw several of their greatest victories, coupled with the destruction of the Covenant as a galactic power. On [[Sigma Octanus IV]], the Covenant were [[Battle of Sigma Octanus IV|defeated]], though at the cost of not only heavy UNSC casualties but also the Covenant attaching a spy probe to the destroyer ''Iroquois'' leading the Covenant to Reach, which they attacked a few days later.<ref>''Halo: The Fall of Reach'', p. 247</ref> On the ground, the SPARTAN-IIs secured a Forerunner [[Sigma Octanus IV Artifact|artifact]] covered in symbols that the Covenant tried to transport out of [[Cote d'Azur]].<ref>''Halo: The Fall of Reach'', p. 205-209</ref>

The [[Fall of Reach]] and [[Battle of Tribute|Tribute]] that followed resulted in staggering losses for both sides, but in the end the Covenant claimed a costly victory.<ref>''Halo: First Strike'', p. 104-105</ref><ref>''Halo 4: The Essential Visual Guide'', p. 177</ref> The ''[[UNSC Pillar of Autumn|Pillar of Autumn]]'' was among the surviving UNSC ships which fled the battle, and made a somewhat blind jump. The destination as described by Cortana was calculated with symbols from the Sigma Octanus IV artifact, coordinates to the Forerunner ring world of [[Halo Array|Halo]]. The ''Pillar of Autumn'' rushed to its destination, pursued by a dozen Covenant warships.<ref>''Halo: The Fall of Reach'', p. 336</ref>

=====The tide turns=====
[[File:H2A - Autumn.jpg|thumb|300px|The [[UNSC Pillar of Autumn|''Pillar of Autumn'']] pushes through the Covenant blockade and escapes [[Reach]].]]

The Covenant suffered a costly defeat on and around [[Installation 04]]. Here, the human survivors from the [[Halcyon-class light cruiser|''Halcyon''-class cruiser]], the ''Pillar of Autumn'', managed to form an effective and surprising resistance to the Covenant. Unwilling to risk damaging the [[Halo|sacred ring]], the Covenant was forced to fight the humans on Halo's surface rather than using their usual bombardment tactics.<ref>''[[Halo: The Flood]]'', p. 187</ref> The Covenant found the UNSC very adept at fighting on the ring's surface, employing their firearms and vehicles in classic guerrilla raids. The Covenant was soundly defeated in numerous raids led by SPARTAN [[John-117]], including an attack on a grounded cruiser, the ''[[Truth and Reconciliation]]'', successfully escaping with the captain of the ''Pillar of Autumn'', Captain Jacob Keyes.<ref>''[[Halo: Combat Evolved]]'', campaign level, [[The Truth and Reconciliation]]</ref> The battle on Halo then suddenly took a turn for the worst for both sides when the Covenant accidentally released an ancient and deadly parasitic race called [[the Flood]]. The Flood, having been imprisoned within Halo for many thousands of years, instinctively spread quickly throughout the ring, killing or assimilating every unsuspecting human and Covenant in their path and would become a third party in the war.<ref>''Halo: Combat Evolved'', campaign level, [[343 Guilty Spark (level)|343 Guilty Spark]]</ref>

During the course of the battle, John 117 discovered the true nature of Halo and proceeded to detonate the crashed ''Pillar of Autumn's'' engines, destroying the ring, and escaped.<ref>'''Halo: Combat Evolved''', campaign level, ''[[The Maw]]''</ref> The destruction of the holy Halo led to [[Supreme Commander]] [[Thel 'Vadamee]] being disgraced and demoted before being branded with the [[Mark of Shame]], leaving him dead in the eyes of the [[Sangheili]]. Only the intervention of the [[Prophet of Truth]] prevented 'Vadamee's certain execution. He was instead given the title of [[Arbiter]] and sent to quell a [[List of known Covenant heretics|heretic]] uprising that had taken root on the [[Threshold gas mine|Forerunner gas mine]] over [[Threshold]].<ref name="thearbiter">''[[Halo 2]]'', campaign level, [[The Arbiter]]</ref>

[[File:Fifth Fleet - H2A.png|thumb|left|300px|The [[UNSC]] [[UNSC Home Fleet|Home Fleet]] shortly before the Covenant attack on Earth.]]

The Covenant discovered Earth as a result of an accident after the ''[[Seeker (AI)|Pious Flea]]'' had been intercepted by the UNSC stealth ship ''[[Apocalypso]]''. After retrieving a Forerunner artifact, the ''Apocalypso'' made a [[Slipspace]] jump directly to Earth. When the ship tumbled into real space and crashed on [[Luna]], the ''Pious Flea'' sent a message to the heart of the Covenant military, containing reconnaissance data, photos, star maps, and the coordinates of the Forerunner artifact, which was now on Earth.<ref>'''i love bees'''</ref>{{verify}} This information was first relayed to the High Prophet of Truth, who, due to his personal socio-political machinations, kept it secret from his fellow Hierarchs.<ref name="tentwenty">'''[[Halo Waypoint]]''', [http://halo.xbox.com/en-us/Universe/Detail/ten-twenty/f4adbef8-e9bc-44f8-aefa-d8e9b69f7139 ''"Ten Twenty"'']</ref> Instead, he began to amass [[Truth's fleet|a massive fleet]] of approximately 500 ships to the command-and-control station ''[[Unyielding Hierophant]]''. The surviving humans from the battles of Installation 04 and Reach, however, discovered the fleet and the direct threat it posed to Earth. Using the captured Covenant [[flagship]] ''Ascendant Justice'', the small group of soldiers lured the fleet into a trap and destroyed it.<ref name="Alamo">'''Halo: First Strike''', ''pages 328-333''</ref>

A few weeks after this defeat, the [[Prophet of Regret]] discovered the location of a significant Forerunner artifact on his own. Without knowledge of the fact the planet housing this artifact was the human homeworld, Regret led a small fleet of fifteen ships to Earth, in order to locate [[Portal at Voi|a portal]] to an installation known as "[[Installation 00|the Ark]]".{{Ref/Reuse|tentwenty}} Though hopelessly outgunned by the UNSC's new orbital defense grid of MAC guns, the Prophet of Regret's [[Solemn Penance|flagship]] managed to break through the human defenses to [[New Mombasa]]. The Covenant ground troops quickly spread through the city, destroying both military and civilian resistance, but a counter-attack by the [[Marines]] and John-117 resulted in their swift defeat. With his fleet burning in orbit, Regret was forced to retreat. His carrier jumped into slipspace from within the city, damaging it severely. Following Regret's jump, waves of Covenant reinforcement forces, including a [[Truth's fleet|support fleet]] sent by the Prophet of Truth, arrived, resulting in a month-long constant engagement on Earth.{{Ref/Generic|Id=lootcrate2|Heading=[[Halo Legendary Crate]]|Subheading=[[Halo Legendary Crate/Data Drops|Data Drop #2]]}}{{Ref/Novel|Id=goo204|Halo: Ghosts of Onyx|Page=204-205}}{{Ref/Reuse|tentwenty}}{{Ref/Site|Id=waypointvergil|URL=https://www.halowaypoint.com/en-us/news/canon-fodder-vergil-reality|Site=Halo Waypoint|Page=Canon Fodder - Vergil Reality|D=15|M=06|Y=2021}}

Unfortunately for Regret, four human ships, the ''[[UNSC In Amber Clad|In Amber Clad]]'' among them, had followed them through their own slipspace rupture to [[Installation 05|Delta Halo]].<ref>''Halo 2'', campaign level, [[Delta Halo]]</ref> Led by John-117, the humans forced their way through Regret's forces until they had reached the Prophet himself. At that moment, ''High Charity'', having learned of Delta Halo, arrived and launched multiple waves of [[Phantom]] dropships to aid Regret. These forces were withdrawn by the Prophet of Truth as part of his plan to remove the Sangheili from power in the Covenant. However, Truth ultimately underestimated the full impact his 'reforms' would have on the Covenant's chances for military victory. The Master Chief [[Assassination of the Prophet of Regret|assassinated]] Regret, dealing a heavy blow to the Covenant's political structure. John-117 narrowly survived only to be captured by the [[Gravemind]], who had already formed a plan to prevent the Covenant from completing their Great Journey.<ref>''Halo 2'', campaign level, [[Regret (Halo 2 level)|Regret]]</ref>

[[File:H2A Great Schism.png|thumb|300px|The Great Schism begins.]]

Meanwhile, the majority of the human forces on ''In Amber Clad'' had traveled to Delta Halo's [[Library]] to obtain the [[Index]], which is the key to firing Halo. Originally, the Covenant had been unaware of the Index's importance, but luckily for them, Arbiter Thel 'Vadamee had obtained [[343 Guilty Spark]], the monitor of [[Installation 04]], while destroying the Heretic base.<ref name="oracle">''Halo 2'', campaign level, [[The Oracle]]</ref> The monitor, known to the Covenant as an Oracle, told the Prophets of the Index and the Arbiter was sent to retrieve the "Sacred Icon". The mission was complicated though by the unexpected release of the Flood. Despite this, the Arbiter successfully reached the Library and prevented the humans from claiming the Index. Just as [[Miranda Keyes]] claimed the index, the Arbiter stole it from her, kidnapping her and [[Sgt. Johnson]]. However, the Index was stolen from the Arbiter by the [[Jiralhanae Chieftain]] [[Tartarus]], who was under the Prophets' orders to retrieve the Index and kill the Arbiter, whom Tartarus knocked down an apparently bottomless shaft.<ref>''Halo 2'', campaign level, [[Quarantine Zone]]</ref> With the Index secure, the Prophets then ordered the Jiralhanae to begin eradicating the Sangheili, thus starting the [[Great Schism]]. Ultimately this led to the death of Tartarus at the hands of 'Vadamee and Johnson and a temporary alliance between the Sangheili and the human forces. Delta Halo was prevented from firing by Miranda Keyes while the Flood infected High Charity and absorbed the [[Prophet of Mercy]], leaving the Prophet of Truth firmly in control over the Covenant Empire.<ref>''Halo 2'', campaign level, [[The Great Journey (level)|The Great Journey]]</ref>

=====Onyx Conflict=====
[[File:Ghosts of Onyx Cover.jpg|thumb|250px|[[SPARTAN Program|SPARTANs]] during the [[Onyx Conflict]].]]
Long before the events around Halo, the classified UNSC colony of [[Onyx]] had been designated the headquarters and training ground for the SPARTAN-III program. However, the UNSC had no idea that the planet was in fact a huge [[Sentinel|Forerunner structure]], integral to the [[Halo Array]], and composed of trillions of [[Onyx Sentinel|Sentinels]].<ref>''Halo: Ghosts of Onyx'', p. 377-378</ref> After John-117's destruction of Alpha Halo, the Sentinels were roused by the disruption of the Halo network and the portal leading into the [[Trevelyan|Shield World]] at the planet's core began to close. At this time, a small group of SPARTAN-IIIs were training in a top honors exercise on the surface. After the humans failed to exchange the proper counter-responses, the Sentinels relabeled the [[Reclaimer]]s as an "aboriginal subspecies" and began to exterminate them.<ref>''Halo: Ghosts of Onyx'', p. 133</ref> Led by [[Kurt-051]], the SPARTAN-IIIs fought a guerrilla war against the Sentinels until Doctor [[Catherine Halsey]] arrived on Onyx and explained the wider situation. Knowing that the Forerunner technology buried in Onyx's core could turn the tide of the war for humanity, Halsey used Forerunner technology to send a message to [[Fleet Admiral]] [[Terrence Hood|Sir Terrence Hood]], requesting reinforcements. Hood deployed [[Blue Team]] to Onyx, who stole [[Bloodied Spirit|a Covenant destroyer]] to reach the planet in time.<ref>''Halo: Ghosts of Onyx'', p. 221</ref>

Meanwhile, the [[Joyous Exultation Covenant|Sangheili forces]] under the leadership of [[Imperial Admiral]] [[Xytan 'Jar Wattinree]] deployed a fleet to Onyx to claim the "sacred relics" for their fight against the Jiralhanae. Xytan would not live to hear of the results of this mission, as he and the majority of his fleet were annihilated by a UNSC [[NOVA bomb]] recovered from Reach.<ref>''Halo: Ghosts of Onyx'', p. 244-245</ref> After Blue Team made landfall, [[Fleet Master]] [[Voro Nar 'Mantakree]]'s fleet arrived at Onyx, taking down hundreds of orbiting Sentinels before discovering the UNSC forces in the recently uncovered Forerunner city below. 'Mantakree personally led the Covenant forces on the surface, before a [[Patterson's battle group|UNSC battlegroup]] arrived and used tactical skill and indirect help from the Sentinels to destroy the majority of the Sangheili fleet before being wiped out by reinforcements from [[Joyous Exultation]], with only [[UNSC Dusk|one ship]] escaping.<ref>''Halo: Ghosts of Onyx'', p. 333</ref>

Underneath Onyx, the Spartans had discovered the [[core room antechamber]] and held off hundreds of Covenant troops before being forced to retreat into the shield world in the core. Kurt-051 sacrificed himself by detonating two [[FENRIS nuclear warhead]]s, killing the entire Covenant force.<ref>'''Halo: Ghosts of Onyx''', ''page 371''</ref> After the core was sealed, Onyx broke up into trillions of Sentinels, guarding the construct. With their forces dangerously depleted, many of the warlike Sangheili subsequently allied with their former enemy, humanity, under the Arbiter's leadership.

=====Arrival of the Flood and Human-Sangheili victory=====
[[File:Final meeting 7.png|thumb|250px|The Sangheili and humans make ready to finish Truth and the Covenant.]] 

Following the Flood infestation of ''High Charity'', the High Prophet of Truth led his remaining fleet to Earth to complete what his occupation forces on Earth had started. Little did he realize that a SPARTAN-II had stowed away with him on board his Dreadnought. By the time Truth arrived at Earth, a full-scale battle in space and on the ground was underway between UNSC and [[Covenant fleet]]s.<ref name="bnet">[http://halo.bungie.net/News/content.aspx?type=topnews&cid=16989 '''Bungie.net''': ''Bungie Weekly Update: 01/23/09 '']</ref>

After several weeks of combat, the [[UNSC Home Fleet]] was nearly wiped out. However, the attacking Covenant armada was also vastly reduced and focused on securing an enormous unearthed Forerunner structure near the ruins of New Mombasa. With the arrival of John-117, the remaining UNSC forces launched an assault on the area, sweeping aside all Covenant resistance and finally launching an all-out attack on the Prophet of Truth's [[Forerunner Dreadnought]]. Unfortunately, even in-atmosphere MAC strikes proved ineffective against the ancient ship's hull, as Truth quickly activated [[the Portal]] and escaped. Events were further complicated by an unexpected attack by the Flood. Thanks to the timely arrival of the Sangheili, the Flood force was vanquished but not before Master Chief recovered a recording from Cortana, who had stayed behind on ''High Charity''. Cortana's message told of a means to stop the Flood on the other end of the portal.<ref>''[[Halo 3]]'', campaign level, [[Floodgate]]</ref>

[[File:H3 LesserArkConflict.png|thumb|left|250px|The battle raging over [[Installation 00]].]]
The final battle of the war was fought on [[2552#December|December 11, 2552]].{{Ref/Reuse|fortitude}} A small fleet of human and Sangheili forces was sent through the portal, leading them to the Ark, just outside the [[Milky Way]]. As they arrived, the Covenant fleet above the Ark immediately attacked. Though the joint human-Sangheili fleet was outnumbered 3–1, the battle ended in defeat for Truth's Jiralhanae fleet. At the same time, UNSC forces were deployed to the surface of the Ark in order to stop Truth, who was attempting to activate the Halo Array from the Ark's [[Installation 00 Citadel|Citadel]].<ref>''Halo 3'', campaign level, [[The Ark (level)|The Ark]]</ref>

Led by the Master Chief, the UNSC forces smashed through the remaining Covenant resistance on the ground. The battle was complicated by the arrival of ''High Charity''. As the Flood began to spread, the Chief and the [[Thel 'Vadamee|Arbiter]] went on to thwart Truth, who died in mid-Flood-infection at the Arbiter's hand with the Flood helping to reach him. John-117 deactivated the Halo Array, preserving all life within its firing pattern. With the Covenant forces completely shattered, Truth's death marked the effective end to the war.{{Ref/Reuse|The Covenant}}  The Flood still remained a threat, but were eliminated by John-117, the Arbiter, Cortana and Sergeant Johnson by firing the isolated replacement Halo over the Ark itself, destroying [[Installation 08]] and damaging [[Installation 00]] severely. Although ''Forward Unto Dawn'' managed to reach the portal, the portal collapsed splitting the vessel in half. Trapped in the rear section of the frigate, John-117 placed himself into cryosleep until he could be retrieved, eventually drifting to the Forerunner shield world of [[Requiem]]. The UNSC's greatest soldier, and humanity's champion, was presumed dead.{{Ref/Reuse|Halo}}

=====The SUNSPEAR mistake=====
{{Main|Operation: SUNSPEAR}}
With humanity under threat of complete annihilation, [[ONI]] sent [[SPARTAN-II]] [[Gray Team]] on a mission deep behind enemy lines. The plan was that if [[Earth]] fell, Gray Team would retaliate against the [[Sangheili]] who led the naval fleets that destroyed human colonies by attacking a Sangheili world.

During the [[Battle for Earth]], Gray Team received a message stating Condition Endgame, meaning that the Covenant had appeared in the [[Sol system]] and the [[Cole Protocol]] had finally failed to protect the planet. Unable to reach [[Sanghelios]] as it was too well defended, Gray Team instead targeted [[Sangheili colonies|the colony world]] of [[Glyke]], home to billions of Sangheili. Though the war ended, Gray Team's ship had a damaged deep-space communications device and thus could not receive any orders to cease or withdraw. Confident that humanity was about to be destroyed, Gray Team took a vote and decided to carry out the mission, hoping that the slaughter would stop humanity's extinction. In December 2552, just days after [[Treaty of 2552|a tentative peace treaty]] was established with [[Thel 'Vadam]] and the [[Fleet of Retribution]], Gray Team destroyed Glyke with a [[NOVA bomb]]. With their ship damaged by the blast, Gray Team was forced to evacuate aboard [[Whiskey Tango Foxtrot One|their lifeboat]] and was left adrift in Glyke's remains, asleep in [[cryo chamber]]s.<ref>''[[Halo: Envoy]]'', p. 177-180</ref>
{{Clear}}

==Aftermath==
[[File:Attend2.PNG|thumb|250px|The ceremony held to honor the fallen.]]
{{Quote|Decades from now, when historians evaluate the war, what will they say about us? Will they claim that our victory was ultimately fruitless? That it failed to secure a lasting peace, or worse, that it was only a prelude to far greater horrors that now lay ahead? My hope -- OUR HOPE -- is that history would instead view this war as a catalyst. That the last thirty years were a crucible, a threshing floor for our species, sifting out our fears and frailties. And that ultimately it made us stronger and more vigilant in the end, fully prepared for whatever will come next. After all, what good is struggle if there is no change? What good is a fire if the sword is not made stronger?|[[Codename: SURGEON]] prefacing the first [[Eleventh Hour reports|Eleventh Hour report]].<ref name="EH">'''[[Eleventh Hour reports]]''': ''Aftermath (1/5)''</ref>}}
On [[2553|March 3, 2553]], a [[Voi Memorial|monument was erected on a hillside]] near the Portal to the Ark to commemorate the billions of men and women killed during the war, and [[John-117]]'s tag was included as he was presumed [[Missing in action|MIA]] by the UNSC, as no Spartan could be declared dead. Lord Hood shook hands with the Arbiter to signify an end to hostilities and [[Treaty of 2552|a formal ceasefire]] was agreed upon between the UNSC and the Arbiter's [[Swords of Sanghelios]].

The Great Schism, now the [[Sangheili-Jiralhanae war]], would continue for at least another six years between Sangheili and Jiralhanae factions, further depleting their now crumbling infrastructure. Their reliance upon the sciences and technology of the Forerunners, while neglecting their own, proved a weakness. The fate of the Prophets, after the infestation of ''High Charity'' resulted in the near-extinction of their race, now hangs in the balance, with little more than a thousand survivors able to flee to unknown space. The most destructive conflict in modern human history had ended in the survival of humanity, but at a staggering cost. Both the UNSC and the former members of the now-broken Covenant then turned to the enormous task of rebuilding their once great societies.

===Recovery and assessment===
After the war, [[Codename: SURGEON]] authored [[Eleventh Hour reports|a series of reports]] detailing the impact of the Covenant War and the postwar status quo. In light of predicted resurgences of Covenant remnants and the Insurrection, as well as new discoveries regarding the Forerunners and their complex relationship with humanity, SURGEON hoped that future historians would view the war as an experience which served to strengthen the resolve of humanity as a whole and prepared them for even worse struggles yet to come.{{Ref/Reuse|EH}} This view echoes SURGEON's own conclusions regarding the Insurrection's impact on humanity's survival in the Covenant War in ''[[Historical/Psychological Analysis of Cole, Preston J.]]''<ref>'''Halo: Evolutions - Essential Tales of the Halo Universe''' - ''The Impossible Life and the Possible Death of Preston J. Cole'', ''page 457''</ref>

===New conflicts===
{{Main|Post-Covenant War conflicts}}
The end of the war only provided a short period of calm for humanity and the former-Covenant species, before threats both new and old began to emerge. The end of the war had had a profound effect on Thel 'Vadam, whose human-sympathetic policies were ultimately a factor in the beginning of the Blooding Years and the rise of the [[Servants of the Abiding Truth]]. [[Shipmaster]] [[Jul 'Mdama]] eventually reunited some of the [[Covenant remnants|disparate factions]] which had surfaced in the wake of the Covenant's dissolution and formed a [[Jul 'Mdama's Covenant faction|new "Covenant" faction]], resuming hostility against humanity. This faction was one of the most prominent players in the [[post-Covenant War conflicts]], which later saw the involvement of reawakened [[Forerunner]] [[Promethean]]s led by the [[Ur-Didact|Didact]]. This short-lived conflict would be fought until [[2558|late-2558]], resulting in the destruction of Jul 'Mdama's Covenant shortly after his death at the [[Battle of Kamchatka]], as well as the Didact's defeat at the [[New Phoenix Incident]] a year prior.
{{Clear}}

In addition to these new threats, the ongoing [[Insurrection]] that had stalemated as a result of the prolonged struggle for survival against the Covenant onslaught began to resurface as humanity's fractured and decimated domain across the galaxy struggled to unify under the resurgent Unified Earth Government. In spite of the diplomatic efforts of [[Fleet Admiral]] [[Terrence Hood]] to rebuild and unite Earth's remaining [[Human colonies|colonies]], many such worlds in the far reaches of space have pledged their loyalty to various Insurrectionist factions in their disillusionment of the UNSC, accusing it of having abandoned them in the war. Some movements such as the highly militant [[New Colonial Alliance]] have collaborated with various Covenant remnants in weapons smuggling and terrorist attacks against the UNSC, necessitating a heightened military response against this new Insurrection as various Covenant factions continued to bolster their ranks.

==Engagements==
{{Human-Covenant War}}

==Timeline==
{{Main|Timeline of the Human-Covenant War}}
{{Expand-section}}

==Non-canon and dubious canon appearances==
===Silver Timeline===
{{Main|Human-Covenant War/Silver}}
In the [[Silver Timeline]], [[The Rubble]] manages to survive for quite a bit longer through the war. As well, the [[Halo Array]] is discovered in a different manner.{{Ref/Site|Id=Debrief1|URL=https://www.halowaypoint.com/news/silver-debrief-a-new-beginning|Site=Halo Waypoint|Page=Silver Debrief: A New Beginning|D=9|M=3|Y=2022}} [[Operation]]s [[Operation: FALLEN WALLS|FALLEN WALLS]], [[Operation: HORIZON|HORIZON]] (on [[Algol]] rather than [[Cascade]]), and [[Operation: IRON FIST|IRON FIST]] took place in the timeline as well.{{Ref/Reuse|Halsey's Computer}}

[[Harvest]] was glassed by the Covenant prior to [[2540]].{{Ref/Site|Id=Halsey's Computer|URL=https://halotheseries.tv/|Site=Halo: The Series|Page=Dr. Catherine Halsey's Computer|D=25|M=3|Y=2022|LocalArchive=Dr. Catherine Halsey's Computer}} In [[2552]], the Covenant [[Attack on Madrigal|attacked]] [[Madrigal]] resulting in [[Silver Team/Silver|Silver Team]] being deployed to the planet.{{Ref/Generic|[[Halo: The Television Series]]|[[Contact]]}}

===Non-canon===
In the ''[[Halo Legends]]'' short ''[[Odd One Out]]'', UNSC forces fought Covenant forces on [[Cronkee]].

==Trivia==
*The "''Great War''", a name for the war used by [[Petra Janecek]], was [[Wikipedia:World War I#Names|originally]] used for the [[World War I|First World War]] prior to the outbreak of the [[World War II|Second World War]] in 1939.
*[[Avery Johnson]] was the only human to witness both the beginning and end of the Human-Covenant War, as he was present when [[Harvest]] was attacked and saw the Prophet of Truth's death, which signified the end of the war. He was also the first human to kill a member of the Covenant.
**Similarly, [[Miranda Keyes]] was born a short time after the war began and died during its last major battle.
*Admiral [[Preston Cole]] questioned the Covenant's apparent difficulty of finding Earth; he pointed out that they could have simply picked up human radio signals and triangulated the source. Cole theorized that the Covenant's systematic destruction of human colonies before assaulting Earth may have been due to an internal scheme within the upper tiers of the Covenant hierarchy that prevented Earth from being targeted sooner; that the destruction of the Outer Colonies before Earth was part of a religious ritual; or that the Covenant were not particularly interested in humanity's homeworld strategically, but for some other, unknown reason. Cole suspected that members of the Covenant military may not have been informed of the particulars of these underlying schemes; in order to prevent hypothetical "rogue elements" within the Covenant military from attacking Earth without authorization from the Covenant leadership, Cole recommended ONI to obfuscate human radio signals in slipspace.<ref>'''Halo: Evolutions - Essential Tales of the Halo Universe''', "The Impossible Life and the Possible Death of Preston J. Cole", ''page 469''</ref> Cole's speculations appear to have been at least partially correct; the Prophet of Truth had a far-reaching plan to increase his personal power, which involved keeping the other Hierarchs and most of the Covenant ignorant of key information, including the location of the human homeworld, until the optimal moment to strike Earth. Truth's plans were partially compromised when the Prophet of Regret discovered the location of the Ark Portal on his own and proceeded to attack Earth, unaware of the human presence.{{Ref/Reuse|tentwenty}} Despite Cole's theories, however, the possibility of triangulating Earth's position from radio signals does not appear to have occurred to the Hierarchs, as evidenced by Truth's more convoluted plan to have Kig-Yar led by [[Reth]] acquire navigation data leading to Earth from [[the Rubble]],<ref>'''Halo: The Cole Protocol''', ''page 285-286''</ref> and the fact that Truth did not discover Earth's location until 2552.{{Ref/Reuse|tentwenty}}
*The length of the Human-Covenant War (28 years) is a reference to the number [[seven]]: 28/4= '''7'''.
**The start and end years are also a reference: 2+5+2+5=2+5+5+2=14/2 = '''7'''.

==List of appearances==
{{Col-begin}}
{{col-3}}
*''[[Halo: The Fall of Reach]]'' {{1st}}
**''[[Halo: The Fall of Reach#2010 bonus content|Adjunct]]''
*''[[Halo: Combat Evolved]]''
*''[[Halo: The Flood]]''
**''[[Halo: The Flood#2010 bonus content|Adjunct]]''
*''[[Halo: First Strike]]''
**''[[Halo: First Strike#2010 bonus content|Adjunct]]''
*''[[i love bees]]''
*''[[Halo 2]]''
**''[[Conversations from the Universe]]''
*''[[Halo Graphic Novel]]''
**''[[Breaking Quarantine]]''
**''[[Second Sunrise Over New Mombasa]]''
**''[[The Last Voyage of the Infinite Succor]]''
*''[[Halo: Ghosts of Onyx]]''
*''[[Starry Night]]''
*''[[Believe]]'' 
**''[[Diorama]]'' {{C|Diorama only}} 
*''[[Halo: Landfall]]''
**''[[Halo: Combat]]''
**''[[Halo: Last One Standing]]''
*''[[Halo: Uprising]]''
*''[[Halo 3]]''
*''[[Halo: Contact Harvest]]''
*''[[Halo: The Cole Protocol]]''
*''[[Halo Wars: Genesis]]''
*''[[Halo Wars]]''
*''[[Halo: Helljumper]]''
*''[[The Life]]''
*''[[Halo 3: ODST]]''
**''[[Sadie's Story]]''
*''[[Halo Legends]]''
**''[[Homecoming]]''
**''[[Odd One Out]]'' {{C|Non-canonical appearance}}
**''[[Origins]]''
**''[[Prototype]]''
**''[[The Babysitter]]''
**''[[The Package (animated short)|The Package]]''
*''[[Halo: Evolutions - Essential Tales of the Halo Universe]]''
**''[[Stomping on the Heels of a Fuss]]''
**''[[Midnight in the Heart of Midlothian]]''
**''[[Dirt]]''
**''[[Headhunters (short story)|Headhunters]]
**''[[Blunt Instruments]]''
**''[[The Mona Lisa]]''
**''[[Palace Hotel]]''
**''[[Human Weakness]]''
**''[[The Impossible Life and the Possible Death of Preston J. Cole]]''
**''[[The Return]]''
{{col-3}}
*''[[Halo: Blood Line]]''
*''[[Remember Reach]]''
**''[[Patrol]]'' {{Im}}
**''[[Deliver Hope]]''
*''[[Halo: Reach]]''
**''[[Data pads]]''
*''[[Halo: Fall of Reach]]''
**''[[Halo: Fall of Reach - Boot Camp|Boot Camp]]''
**''[[Halo: Fall of Reach - Covenant|Covenant]]''
**''[[Halo: Fall of Reach - Invasion|Invasion]]''
*''[[Halo: Glasslands]]'' {{Mo}}
*''[[Halo: Combat Evolved Anniversary]]''
**''[[Terminal (Halo: Combat Evolved Anniversary)|Terminals]]''
*''[[Halo: The Thursday War]]'' {{Mo}}
*''[[Halo 4: Forward Unto Dawn]]''
*''[[Halo 4]]'' <small>([[Prologue]] Only)</small>
*''[[Halo: Spartan Assault]]'' {{Mo}}
*''[[Halo: Initiation]]''
*''[[Halo: Escalation]]''
*''[[Halo: Broken Circle]]''
*''[[Halo 2: Anniversary]]''
**''[[Terminal (Halo 2: Anniversary)|Terminals]]''
*''[[Halo: New Blood]]''
*''[[Hunt the Truth]]''
*''[[Halo: Spartan Strike]]''
*''[[Halo: Hunters in the Dark]]'' {{Mo}}
*''[[Halo: Last Light]]'' {{Mo}}
*''[[Halo: The Fall of Reach - The Animated Series]]''
*''[[Halo 5: Guardians]]'' {{Mo}}
**''[[Halo 5: Guardians Limited Edition dossiers|Limited Edition dossiers]]'' {{Mo}}
*''[[Halo: Ground Command]]''
*''[[Halo Mythos]]''
*''[[Halo: Smoke and Shadow]]'' {{Mo}}
*''[[Halo Wars 2]]'' {{Mo}}
*''[[Halo: Envoy]]'' {{Mo}}
*''[[Halo: Rise of Atriox]]''
*''[[Halo: Retribution]]'' {{Mo}}
*''[[Halo: Legacy of Onyx]]''
*''[[Halo: Bad Blood]]'' {{Mo}}
*''[[Halo: Collateral Damage]]''
*''[[Halo: Fireteam Raven]]''
*''[[Halo: Silent Storm]]''
*''[[Halo: Official Spartan Field Manual]]''
*''[[Halo: Battle Born]]''
*''[[Halo: Renegades]]'' {{Mo}}
*''[[Halo: Oblivion]]''
*''[[Halo: Meridian Divide]]''
*''[[Halo: Shadows of Reach]]'' {{Mo}}
**''[[Sacrifice]]'' {{Mo}}
{{col-3}}
*''[[Halo: Point of Light]]'' {{Mo}}
*''[[Halo: Divine Wind]]'' {{Mo}}
*''[[Become]]''
**''[[Unspoken]]'' {{Mo}}
**''[[Project Magnes (trailer)|Project Magnes]]'' {{Mo}}
**''[[Lightbringers]]''
*''[[Halo Infinite]]''
*''[[Halo: The Television Series]]''
*''[[Halo: The Rubicon Protocol]]'' {{Mo}}
*''[[Halo: Winter Contention]]''
*''[[Halo: Outcasts]]'' {{Mo}}
*''[[Halo: Sunrise on Sanghelios]]'' {{Mo}}
*''[[Halo: Saturn Devouring His Son]]'' {{Mo}}
*''[[Halo: Battle for the Blood-Moon]]'' {{Mo}}
*''[[Halo: Hippocratica]]''
{{col-end}}

==Notes==
<references group="notes"/>

==Sources==
{{Ref/Sources|3}}
{{Human wars}}
{{Covenantwars}}

[[Category:Wars]]
[[Category:Human-Covenant War| ]]
[[Category:History of the UNSC]]
[[Category:Battles of the Human-Covenant War| ]]