Editing Human-Covenant War

{{Era|HCW}}
{{References}}
{{Battle Infobox
|name=Human-Covenant War 
|prev=[[Interplanetary War]], [[Insurrection]]
|conc=[[Insurrection]] 
|next=[[Sangheili civil war]]
|image=[[File:Human-Covenant War.png|400px]]<sup>Clockwise from top left: UNSC and Covenant infantry clash, the UNSC responds to a Covenant invasion of a UNSC colony world, a squad of SPARTANs engaging the [[Sangheili]] in the [[Fall of Reach]], the [[Battle_of_Earth#The_Flood_on_Earth|invasion of the]] [[Flood]] on [[Battle of Earth|Earth]], the [[Great Schism]] over ''[[High Charity]]'', the ''Pillar of Autumn'' fleeing from the Fall of Reach.</sup>
|date=February 11, [[2525]]<ref>[[First Battle of Harvest]]</ref> – February 2553 <small>(informal ceasefire)</small><ref name="ceasefire">'''Halo: Glasslands''', ''pages 358-361''</ref> <br/> *[[2553#March|March 3, 2553]] <small>(official cessation of hostilities)</small><ref name="Dr. Iqbal">'''[[Halo: Evolutions - Essential Tales of the Halo Universe]]''', ''[[From the Office of Dr. William Arthur Iqbal]]''</ref>
|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='''Pyrrhic human and [[Sangheili]] victory<ref>'''[[Believe]]''', ''[[Museum]]''</ref> 
*The Covenant Empire falls to the combined forces of the Covenant separatists and UNSC
*Widespread [[The Flood|Flood]] infection of the galaxy averted
*Any encountered [[Forerunner]] installations deactivated
*Human and Sangheili forces reconcile
|side1='''[[United Nations Space Command]]'''
<br>[[Covenant separatists]]
<br>[[Forerunner]] constructs
|side2=Covenant
|side3=[[Flood]]
|commanders1=
[[UNSC High Command|High Command]]
*[[Fleet Admiral]] [[Terrence Hood|Lord Terrence Hood]]
*[[Admiral]] [[Preston Cole]]† (MIA, assumed KIA)
*[[Admiral]] [[Margaret Orlenda Parangosky]]
*[[Admiral]] [[Michael Stanforth]]†
*[[Admiral]] [[Danforth Whitcomb]]†
Sangheili
*[[Thel 'Vadam|Arbiter Thel 'Vadam]]
*[[Rtas 'Vadum|Commander Rtas 'Vadum]]
Forerunner constructs
*[[343 Guilty Spark]]†
|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]]†
*[[Rtas 'Vadum|Special Operations Commander Rtas 'Vadumee]] <small>''(pre-Great Schism)''</small>
*[[Ripa 'Moramee]] †
*[[Thel 'Vadamee]] <small>''(pre-Great Schism)''</small>
|commanders3=[[Gravemind]]†
|forces1=
|forces2=
|forces3=
|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 (short story)|Palace Hotel]]", ''page 351''</ref> billions more during invasion of Earth<ref>'''Halo: Glasslands'''. ''page ???''</ref>
*Widespread infrastructure and structural damages to UEG colonies
;Moderate separatists casualties
*Thousands of separatists casualties, due to their late entry of the war 
*Possible damages on the [[Sangheili]]s' homeworld [[Sanghelios]]
|casual2=
;Heavy casualties for all Covenant races
*Destruction of the Covenant Holy City, ''[[High Charity]]''
*Destruction of the Covenant battle station, ''[[Unyielding Hierophant]]''.
*Devastation of a Sangheili colony, [[Joyous Exultation]].
|casual3=
;Extreme casualties for the Flood
*High Charity destroyed  
}}
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> and the '''Great War''',<ref>'''Halo: First Strike''' (2010), ''[[Petra]]''</ref> was a major interstellar conflict pitting the [[Unified Earth Government]] and its [[United Nations Space Command]] against the [[Covenant Empire]] during the mid-26<sup>th</sup> century between [[2525#February|February 11, 2525]] and [[2553|March 3, 2553]]. There were two additional factions sporadically involved in the conflict; them being the [[Flood]], and a small number of surviving [[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 Covenant whose [[Hierarchs|High Prophets]] made a discovery which led them to believe that humans were directly related to the Forerunners, contradicting their ancient religion. Seeking to keep various political and religious orders intact, a war of genocide was declared against the human race. Over the next few decades the Covenant with superior firepower, numbers and technology, would repeatedly overpower the UNSC across hundreds of worlds, including heavily defended strongholds such as [[Reach]]. Humanity would only win 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. While the [[Battle of Installation 00|deciding battle]] of the war was fought on [[2552#December|December 11, 2552]],<ref name="fortitude">[http://halo.xbox.com/en-us/intel/featured/video/herofortitude/bfe5038b-314a-4f17-a6be-f7613e0e3788 '''Halo Waypoint''', ''Hero-Fortitude'']</ref> an informal ceasefire was not agreed upon until [[2553#February|February 2553]].<ref name="ceasefire"/> The official cessation of hostilities was declared on [[2553#March|March 3, 2553]].<ref name="Dr. Iqbal"/> The war was incredibly costly to both sides, with over twenty-three billion humans and billions of Covenant killed during the hostilities. 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.

==History==
===Declaration of war (2525)===
{{main|First Battle of Harvest}}
[[File:SSgt Avery Johnson, UNSC Marine Corps.JPG|thumb|200px|Staff Sergeant Johnson leading Colonial Militia during the Covenant invasion of Harvest.]]
Humanity and the Covenant first came into direct contact on February 3rd, 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. The raid continued to [[This End Up|another]] unfortunate human ship. Some time after, [[Sif]], Harvest shipping operations AI, investigated the raids and reported her findings to an [[Jilan al-Cygni|undercover ONI agent]].<ref group="notes">Prior to the contact, Sif and Jilan al-Cygni were unaware of the alien parties responsible behind the raid, thinking that it was one of the many common Insurrectionist activities.</ref> 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|Avery Johnson]], and the Kig-yar privateers. When the Covenant returned with [[Rapid Conversion|another ship]] and a contingent of [[Jiralhanae]], the UNSC proposed a meeting (via pictogram) with the intention to make amends and to trade with the alien species. 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.

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]]. 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 [[032 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. 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. The hierarchy declared that the humans destroyed the holy reliquary on Harvest, and ordered the entire race to be eradicated.

The first battle of the war was the extended, albeit one-sided, engagement which took place on Harvest. The UNSC managed to delay the Covenant long enough to evacuate many of Harvest's civilians. Eventually, the Covenant ship responsible for the attack [[Glassing|glassed]] the planet's surface.

===Open war (2525-2552)===
[[File:Outcome of Second Battle of Harvest.png|thumb|200px|Cole's fleet destroys the Covenant ship in the Second Battle of Harvest.]]
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. 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, or the rapid deployment of Spartan teams. 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> For twenty-seven years, the Covenant whittled down the UNSC planet by planet. Despite this, the UNSC kept the war secret to the public in the first few months of the war.

Realizing the threat posed to humanity by the Covenant, the UNSC [[Colonial Military Administration]] gave [[Vice Admiral]] [[Preston Cole]] the command of the then-largest fleet in human history with orders to retake Harvest. Cole [[Second Battle of Harvest|retook Harvest]] in [[2526]], and then spent 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]]. 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. Because of the threat the Covenant posed, the UNSC began deploying the [[SPARTAN-II Program|SPARTAN-II]]s, 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".

===The Apex and the Arbiter (2531)===
[[File:Vlcsnap-126257.png|thumb|250px|left|The [[Prophet of Regret]] converses with [[Arbiter]] [[Ripa 'Moramee]] on the destruction of the human race.]]
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>'''[[Halo Wars]]''', campaign level ''[[Scarab (Level)|Scarab]]''</ref> In spite of the UNSC's inferiority in comparison to the Covenant, the Prophets apparently considered their armed forces to be powerful enough to pose a threat to the Covenant proper. Seeking a more efficient solution, the [[Prophet of Regret]] dispatched [[Ripa 'Moramee|an Arbiter]] to Harvest to claim a Forerunner [[Relic|artifact]] buried under the north pole of Harvest.

Preston Cole counter-attacked by leading a fleet composed of the {{UNSCShip|Spirit of Fire}} and the {{UNSCShip|Prophecy}} back to Harvest after receiving a message from an [[ONI]] [[UNSC prowler|prowler]]. The battle was a victory, despite major casualties. Upon discovering that the Covenant, under the command of 'Moramee, had excavated Forerunner artifacts in the northern polar region, [[Captain (Navy)|Captain]] [[James Cutter]] deployed ground forces to remove the Covenant occupation. After a heated fight on the surface, the UNSC forces were able to examine the artifact, a star map, and realized the information within had led the Covenant to another human colony: [[Arcadia]].

[[File:ApexBattleImage.png|thumb|250px||right|The {{UNSCShip|Spirit of Fire}} engages a Covenant [[Covenant Destroyer|destroyer]] in Shield 0459.]]

As predicted, the Covenant [[Battle of 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 [[Shield 0459|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.

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 [[Unidentified Forerunner dreadnought class|Forerunner dreadnoughts]] held there. 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.

===SPARTAN-III (2531)===
{{Main|SPARTAN-III Program}}
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 [[Chi Ceti IV]].<ref>'''Halo: Reach''', ''[[Data pads|Data pad 14]]''</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.

===Crisis (2534-2535)===
[[File:CP armor.png|thumb|200px|A member of Gray Team at the [[Battle of the Rubble]].]]
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. Meanwhile, Covenant forces began to encroach on the [[Inner Colonies]]. 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. [[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. Upon learning of this, the [[Prophet of Regret]] declared such weapons as heresy, and as a result dispatched [[Thel 'Vadam|Thel 'Vadamee]] to destroy the source of the modified weapons: a remote asteroid habitat known as [[the Rubble]].

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. 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. 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.

By the time of the [[Battle of Jericho VII]] in 2535, most of the Outer Colonies had been destroyed.

===Continuing war (2536-2551)===
[[File:Origins ii Human-CovenantWar.jpg|thumb|right|225px|Humanity, heavily out-gunned, lost much ground to the Covenant.]]
For fifteen years, the war ground on in a predictable pattern; costly victories on the ground for UNSC forces, with near total Covenant space superiority. 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]], 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.

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, followed by the [[Battle of Actium|defeat at Actium]] in [[2545]], defeat during the [[Fall of Arcadia]] and the [[Siege of Paris IV|loss of Paris IV]] in 2549. 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. 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. 

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. 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. A painting depicting the battle, titled "[[Admiral Cole's Last Stand]]" was created and by [[2552]], it hung on the wall of the [[HIGHCOM Facility Bravo-6]] on [[Sydney]], Earth.<ref>'''[[Halo: Evolutions]]''', ''[[The Impossible Life and the Possible Death of Preston J. Cole]]'', ''pages 472-485''</ref>

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. 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> 

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]]''', ''page ??''</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. 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]].

The [[Fall of Reach]] that followed resulted in staggering losses for both sides, but in the end the Covenant won a Pyrrhic victory. 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.

====The tide turns====
[[File:Battle of Reach.jpg|thumb|right|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 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. 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. 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.  

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, much to the Covenant's horrified dismay. The destruction of the holy Halo construct and the later loss of the [[flagship]] ''[[Ascendant Justice]]'' to the surviving UNSC forces 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 [[Heretic]] uprising that had taken root on the [[Threshold gas mine|Forerunner gas mine]] over [[Threshold]].

[[File:UNSC Home Fleet.JPG|thumb|left|250px|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 ''[[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 the [[Luna|Moon]], 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> 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.

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 [[The Portal|a portal]] to an installation known as "[[Installation 00|the Ark]]".<ref name="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. Directly following Regret's jump, a reinforcement force sent by the Prophet of Truth arrived, resulting in a month-long constant engagement on Earth.<ref name="tentwenty"/>

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]]. With the orders "Find out why he came to Earth; why he came here," John-117 was hard-dropped with a complement of [[Orbital Drop Shock Trooper|ODSTs]] to Delta Halo's surface. 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 assassinated Regret, dealing a heavy blow to the Empire's political structure. The Prophet of Truth then gave the order to glass the temple in which Regret resided. 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.

[[File:War.jpg|thumb|right|250px|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. 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, then 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. 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 Separatists and the human forces. Delta Halo was prevented from firing by Miranda Keyes while the Flood infected and absorbed the [[Prophet of Mercy]], leaving the Prophet of Truth firmly in control over the Covenant Empire.

====The Battle of Onyx====
[[File:Ghosts of Onyx Cover.jpg|thumb|250px|right|[[SPARTAN Program|SPARTANs]] at the [[Battle of Onyx]].]]
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 [[Forerunner]] construct, integral to the [[Halo Array]], and containing trillions of [[Onyx Sentinel|Sentinels]]. 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 [[Sharpened Shield|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. 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.

Meanwhile, the [[Covenant separatists]] under the leadership of [[Imperial Admiral]] [[Xytan 'Jar Wattinree]] had deployed a fleet to Onyx to claim the "sacred relics" for their fight against the Jiralhanae and the other loyalists. 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. 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 separatist fleet before being wiped out by reinforcements from [[Joyous Exultation]], with only [[UNSC Dusk|one ship]] escaping.

Underneath Onyx, the Spartans had discovered the [[core room antechamber]] and were preparing to enter the Shield World. They managed to hold off hundreds of Covenant troops before being forced to retreat into the core, while Kurt-051 sacrificed himself by detonating two [[FENRIS nuclear warhead]]s, killing the entire separatist force. Following the core being sealed, Onyx broke up into trillions of Sentinels, guarding the construct. With the Covenant separatists dangerously depleted, the warlike Sangheili were finally forced to ally with their enemy, humanity.

====Arrival of the Flood and Sangheili/human victory====
[[File:Final meeting 7.png|thumb|left|200px|The Sangheili and humans make ready to finish Truth and the Covenant.]] 
[[File:H3 E3 Orbital Battle.jpg|thumb|right|300px|The battle between Covenant separatists and loyalists, raging over [[Installation 00]].]]
{{Quote|In memory of those fallen in the defense of Earth and her colonies - March 3, 2553|[[Voi Memorial]]}}

Following the Flood infestation of ''High Charity'', the High Prophet of Truth led the remaining loyalist 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.

After a slug-fest lasting several weeks, 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.

The final battle of the war was fought in [[2552#December|December 11, 2552]].<ref name="fortitude"/> A small fleet of human and Sangheili forces was sent through the portal, leading them to the Ark, just outside the [[Milky Way Galaxy]]. 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 the Covenant loyalist 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 [[Forerunner Citadel|Citadel]].

[[File:Attend2.PNG|thumb|right|200px|The ceremony held to honor the fallen.]]
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. 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 both installations. Although Forward Unto Dawn managed an emergency slipspace jump, 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. 

Some months later, in [[2553|March 3 of 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|Spartan-117]]'s name was included as he was presumed MIA by the UNSC, as no Spartan could be declared dead. Lord Hood shook hands with the Arbiter to signify an end to hostilities. 

The Great Schism would continue for at least another six years between Elite and Brute factions, further depleting their now crumbling infrastructure. Their blind reliance upon the sciences and technology of the Forerunners, while neglecting their own, proved a fatal weakness. The fate of the Prophets proved especially ironic, as the infestation of High Charity resulted in the near-extinction of their race, while the survivors fled to unknown space. The most destructive conflict in human history had ended in victory, 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.

==Timeline==
===2524 ''(Pre-war)''===
*A damaged human civilian freighter, ''[[Horn of Plenty]]'', suffers a slipspace drive malfunction from Harvest to Madrigal, forcing the unmanned freighter to exit back into normal space. A Covenant vessel, ''[[Minor Transgression]]'', comes into contact after hours of the freighter's isolation. The Covenant vessel targets the freighter, and a Jackal boarding crew enter.

===2525===
*The [[Skirmish Over Harvest|first battle]] between humanity and the Covenant takes place prior to the outbreak of the war. Humanity attempts to gain a truce between the races through a pictogram of trade and peace between the Covenant and humanity, but to no avail. ''(Pre-War)''

*The Covenant launch a full-scale [[First Battle of Harvest|assault]] on Harvest, glassing the planet. Afterward, the Minister of Fortitude, Vice-Minister of Tranquility, and the Philologist become the [[Hierarchs|High Prophets]] of [[Prophet of Truth|Truth]], [[Prophet of Regret|Regret]], and [[Prophet of Mercy|Mercy]], and declare war on humanity.

*Shortly after the attack on Harvest, the colonies of [[Green Hills]] and [[Second Base]] are glassed.

*The [[Battle of Chi Ceti]] takes place, marking the first real ship-to-ship engagement between humanity and the Covenant. It is also the first uncontested human victory.

===2526===
*[[Second Battle of Harvest]]. The UNSC and Covenant meet in a fleet-action for the first time; though only one Covenant ship faces a UNSC battle-group of 40, it is a rare (or unique) superdestroyer with a power comparable to a Covenant assault carrier. The battle is a high-priced victory for the [[UNSCDF]], costing the UNSC 13 ships--about one third of the battle-group that was assembled to face the threat. The Covenant would return to Harvest later in the year, and the battle for the planet and its surrounding systems, dubbed by the UNSC as the [[Harvest Campaign]], would last for the next five years.
*[[Battle of Circinius IV]]. The Covenant attacked the UNSC [[Corbulo Academy of Military Science]] on [[Circinius IV]], catching the cadets there off guard and sparking a massive ground battle for control of the Academy. The Spartan [[Blue Team]] was deployed to fight the Covenant soldiers and to evacuate the trainees who were forced to engage the enemy in close-quater combat. The battle resulted in the near-complete extermination of the planet's population, including those of the Corbulo Academy save for the survivors of [[Hastati Squad]].
*[[Battle of Alpha Aurigae]]. Another ship-to-ship battle, where the UNSC outnumber the Covenant almost 10-1, but lost a third of the ships. This was one of the rare naval "victories" for the UNSC, won because of their numerical superiority over the Covenant in that battle.

===2528===
*[[Battle of XI Boötis A]], the UNSC fleet of 70 warships destroy 8 enemy vessels, losing 30 of their own in the process
*[[Madrigal]] is glassed by The Covenant

===2528 or 2529===
*[[Battle of Hat Yai]].

===2530===
*The Covenant [[Battle of Eridanus II|destroys]] the UNSC colony world of [[Eridanus II]]
*[[Battle of Groombridge-1830]], 11 UNSC Destroyers are lost in attempt to defeat a Covenant fleet of 3 warships

===2531===
*The UNSC finally manages to [[Harvest Campaign#Final Liberation of Harvest|retake Harvest]], ending the five-year long Harvest Campaign in a UNSC victory.
*[[Battle of Arcadia]]
*[[Battle of Shield 0459]]
*[[Kurt-051]] is kidnapped by Section III of ONI to train the classified [[SPARTAN-III]]s, in a need for more supersoldiers to fight the Covenant.

===2535===
*In an effort to better protect the remaining human worlds, the UNSC implements the [[United Nations Space Command Emergency Priority Order 098831A-1|Cole Protocol]].
*The Covenant [[Glassing|destroys]] the UNSC colony world of [[Jericho VII]] in the [[Battle of Jericho VII]].
*[[Battle of Charybdis IX]].
*[[Battle of the Rubble]].
*In the course of four short years, UNSC forces have been hammered, despite excellent leadership and tactical brilliance. It is simply a matter of being outgunned; Covenant kill ratios tend to top three to one in ship-to-ship combat. By 2535, virtually all of the [[Outer Colonies|Outer Colony]] worlds have been glassed by the Covenant.

===2536===
*Covenant forces begin to swarm into the [[Inner Colonies]]. For several years the war falls into a pattern: humans win isolated battles, typically during ground operations, but at a horrible cost and rarely without the Spartans' assistance. In space combat, the humans are losing at a precipitous rate, and one by one, the colonies fall.

===2537===
*Discovery of Covenant Manufacturing Plant [[K7-49]] at the [[Battle of New Harmony]].
*[[Battle of New Constantinople]], Covenant [[glassing]] of [[New Constantinople]].
*[[Battle of Leonis Minoris]], Covenant destruction of [[Leonis Minoris]].
*[[Siege of the Atlas Moons]] was a rare victory for the [[UNSC]], as victories in space-based fighting were uncommon for the UNSC Fleet.
*[[Operation: PROMETHEUS]]: UNSC Victory. [[SPARTAN-III]] [[Alpha Company]] is killed by Covenant forces.

===2539===
*[[Battle of Kholo]], Covenant forces glass the colony of [[Kholo]].

===2543===
*On March 6 the [[Battle of 18 Scorpii]] takes place. In the battle prior-unknown Independent/Insurrectionist human forces assist three UNSC destroyers in defeating a Covenant CPV destroyer.
*[[Cole|Vice Admiral Preston J. Cole]] is presumed to have made [[Admiral Cole's Last Stand|his last stand]] at the [[Battle of Psi Serpentis]] on April 18.  Over 300 Covenant ships destroyed in the battle.

===2544===
*[[Battle of Miridem]], the SPARTAN-II [[Sheila-065]] is killed while protecting Dr. Catherine Halsey on Miridem. Halsey is subsequently captured by Covenant forces, and is placed on board a Covenant assault carrier in the [[Third Fleet of Glorious Consequence]].
*[[Raid on the Third Fleet of Glorious Consequence]], following Halsey's capture by the Covenant, the Office of Naval Intelligence initiates an operation to rescue her with the assistance of five SPARTAN-IIs. The operation is a success, and Halsey is rescued, at the cost of two of the Spartans.

===2545===
*[[Operation: TORPEDO]]: UNSC victory. All participating SPARTAN IIIs, with the exception of Tom-B292 and Lucy-B091 of [[SPARTAN-III]] [[Beta Company]] are killed by Covenant forces.
*[[Battle of Actium]]: Covenant victory. The [[53rd Armored Division]] is wiped out in a nuclear attack aimed at halting the Covenant offensive on the UNSC colony of [[Actium]]; Although casualties are high, the Covenant ultimately glass the planet.

===2546===
*[[Sargasso]] is [[Battle of Sargasso|attacked]] by the Covenant. This engagement marks the first appearance of the [[Type-46 Infantry Support Vehicle]].<ref>'''[[Halo: The Essential Visual Guide]]''', ''page 186''</ref>
*[[Battle of New Llanelli]]: Covenant victory, New Llanelli is glassed.

===2547===
*The UNSC colony of [[Skopje]] is [[Battle of Skopje|destroyed]] by the Covenant.

===2549===
*[[Siege of Paris IV]], Covenant victory.
*[[Fall of Arcadia]], Covenant victory, Arcadia is glassed.<ref>[[Halo Waypoint]] article on Arcadia</ref>

===2552===
====April====
*[[Battle of Fumirole]]. [[Thom-293]] is killed and [[Catherine-B320]] loses her arm.

====July====
*[[Battle of Draco III]]. Covenant kill all UNSC ground forces and captured thousands of civilians. Later a [[SPARTAN-II|SPARTAN]] squad arrive and kill all Covenant forces only to find that the civilians were killed by ravenous, raging Grunts and Jackals.

*[[Battle of Sigma Octanus IV]]. The single greatest UNSC victory since [[Harvest]]. However, the Covenant gain what they seek: the location of [[Installation 04]]. They also discover the human presence on [[Reach]].

*The Covenant discover Reach, and send in an advance invasion force, beginning the prolonged [[Fall of Reach|Battle of Reach]].

====August====
*[[Battle of Tribute]]. Along with other colonies in the [[Epsilon Eridani System]], [[Tribute]] is invaded by Covenant forces. The colony is not glassed instantly, but remains under siege by Covenant forces for some time.

*[[Raid on Verge]]. A Covenant [[Beacon]] transmitting [[Helium|helium-3]] for ships blockading Tribute is destroyed by [[Team Black]].

*[[Battle of Line Installation 1-4]]. A UNSC ship on a covert mission, as well as a Covenant Assault Carrier, crash on a remote moon with a [[Line Installation 1-4|Forerunner relic]]. In the ensuing engagement, the surviving UNSC forces side with the Covenant against the installation's defense systems.

*The Fall of Reach ends. On August 30th, 314 Covenant ships destroy over 130 UNSC ships and 20 [[ODP]]s for the loss of at least two-thirds of their fleet. It is a major Covenant victory: Reach is the last major stronghold before [[Sol]]. The ''[[UNSC Pillar of Autumn]]'' escapes.

====September====
[[File:Concept-04-Destruction.jpg|thumb|right|300px|Installation 04 after its destruction.]]

*[[Battle of New Jerusalem]]. Following an attack on the UNSC colony of [[New Jerusalem]], the [[26th Marine Expeditionary Force]] is sent to reinforce the UNSC forces already present. The colony is eventually lost to the Covenant and the survivors fall back to Earth.

*[[Battle of Installation 04]]. The ''Pillar of Autumn'' engages the Covenant Fleet of Particular Justice at Halo Installation 04. After four days the battle degenerates into a four-way melee as the Flood organisms are released and Forerunner constructs, Sentinels seek to contain the outbreak. The crew of the ''Pillar of Autumn'' are instrumental in preventing the Flood from escaping and the installation from firing by destroying the installation. There are only a handful of survivors.

*[[Skirmish over Threshold]]. UNSC survivors from the Battle of Installation 04 rally in orbit over [[Threshold]].  Using their limited resources to the fullest they manage to capture the Covenant vessel ''[[Ascendant Justice]]'' and use it to escape.

*[[Raid of Reach]]. John-117 and some of the survivors of the Battle of Installation 04 raid Reach to rescue a [[SPARTAN]]-II team trapped on Reach by a Covenant fleet. They rescue the Spartan squad leaving a great deal of damage to the Covenant fleet ships and the ground forces.

*[[Operation: FIRST STRIKE]]. Six [[SPARTAN-II]] super soldiers route and destroy a fleet of 500 Covenant warships preparing to jump to Earth. This is the single greatest victory, for the humans during the entire war and the single greatest loss to the Covenant.

====October====
*[[Battle of Earth]]. 15 Covenant ships assault Earth, defended by the [[UNSC Home Fleet]] and 300 ODPs. The Covenant were not expecting the heavy human presence, as well as their new orbital MAC defenses, and are completely destroyed save for the ''[[Solemn Penance]]''- the [[High Prophet of Regret]]'s personal assault carrier, and the ''[[Pious Inquisitor]]''. However, a fleet of Covenant capital ships appears soon after, prolonging the battle.

====November====
*[[Battle of Installation 05]]. The ''Solemn Penance'' arrives at [[Installation 05]], being pursued by four small UNSC warships. Only one, the {{UNSCship|In Amber Clad}}, arrives in time to participate in the battle.
*The Prophet of Regret is assassinated by John-117.
*The [[Great Schism]] begins. Covenant forces are thoroughly divided between the Sangheili and the Jiralhanae. Every race in the Covenant takes sides.
*The [[Prophet of Mercy]] is later killed by a Flood Infection Form.
*Once again, the installation is prevented from firing and the Flood appear to take control of the installation and High Charity.

*[[Battle of Onyx]]. The destruction of [[Installation 04]] wakes dormant Forerunner installations, including the Sentinels on Onyx which then threaten the UNSC base there. The SPARTAN-IIs of Blue Team fight their way off of [[Earth]] and commandeer a [[Covenant Destroyer]], the ''[[Bloodied Spirit]]'', to relieve [[Onyx]]. Covenant and UNSC ships converge on Onyx but ultimately all are destroyed except for the {{UNSCship|Dusk}}. UNSC survivors retreat within the Onyx [[Shield World]].

*The Battle of Earth continues. The Covenant, led by the Prophet of Truth, arrive at Earth in force, to reinforce the Covenant forces already present. During the following week, [[UNSC Marine Corps|Marines]], with help of the [[Covenant separatists|separatists]], pushes back the Covenant invaders.

====December====
*[[Battle of Installation 00]].
*All Covenant vessels are destroyed over the Ark by the Sangheili Fleet of Retribution.
*The final Covenant religious leader, the [[Prophet of Truth]], is executed by the Arbiter with help from the Flood. The Master Chief stops the Ark from firing the Halo Rings.
*''High Charity'' is destroyed by the Master Chief after he blasts the city's main reactors causing them to go critical.
*The Battle of [[Installation 04B]]. Thel 'Vadam, John-117 and Johnson battle to the control room that's on [[Installation 04B]]. Guilty Spark runs rampant, killing Johnson before being destroyed. [[Installation 04B]]’s Sentinels turned on John-117 and Thel 'Vadam. The unfinished Installation 04 is activated, damaging the Ark and destroying the entire Flood infestation including the [[Gravemind]]. These final events ended The Human-Covenant War. However, the ''Dawn'' is torn in half while entering the portal home, sending 'Vadam to Earth, but leaving John and Cortana lost in space.
*The Arbiter returns to Earth in the front half of ''Forward Unto Dawn'', crashing into the Indian Ocean. He is safely cut out of the wreckage by UNSC forces.

===2553===
====February====
*Fleet Admiral Hood meets with Arbiter Thel 'Vadam on [[Sanghelios]]. They agree to a ceasefire between humanity and the Sangheili loyal to [[Vadam]].<ref name="ceasefire"/>

====March====
*While the fighting finished in December and a ceasefire was agreed upon in February, hostilities are not ceased officially until March.<ref name="Dr. Iqbal"/> The UNSC erect a [[Voi Memorial|monument]] on a hillside near the Ark's gateway to commemorate those who died during the war, particularly during the Battle on Installation 00. Two of the most prominent figures listed on the memorial are John-117 and [[Catherine Halsey|Dr. Catherine Halsey]],<ref>'''Halo: Glasslands''', page ''435''</ref> though both remain alive. Thel 'Vadam and his retinue depart for Sanghelios.

==Trivia==
*"''Great War''", a term used by [[Petra Janecek]], is likely a reference to the original, widely adopted name of the [[Wikipedia:First World War#Names|First World War]] used throughout the conflict until the outbreak of the [[World War II|second war]] in 1939. The political landscape of the post-war Milky Way galaxy is very similar to events seen between 1918 and 1939 may possibly foreshadow a second galactic war with Earth and her colonies pitted against the remains of the Covenant Empire.
*The very first Covenant species to encounter humanity were the [[Kig-Yar]], the [[Unggoy]], the [[Huragok]], and the [[Jiralhanae]], - in that order - all prior to the inception of the war.
*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 Truth killed, which signified the end of the war. He was also the first human to kill a Covenant member.
*Admiral [[Preston Jeremiah Cole|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 name="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 name="tentwenty"/>
*The length of the Human-Covenant War is a [[seven]] reference. The war lasted a total of 28 years. 28 is divisible by 7: 28/4='''7'''

==List of appearances==
{{Col-begin}}
{{col-3}}
*''[[Halo: Combat Evolved]]''
*''[[Halo 2]]''
*''[[Halo 3]]''
*''[[Halo 3: ODST]]''
*''[[Halo Wars]]''
*''[[Halo: Reach]]''
*''[[i love bees]]''
{{col-3}}
*''[[Halo: The Fall of Reach]]'' {{1st}}
*''[[Halo: The Flood]]''
*''[[Halo: First Strike]]''
*''[[Halo: Ghosts of Onyx]]''
*''[[Halo: Contact Harvest]]''
*''[[Halo: The Cole Protocol]]''
*''[[Halo Graphic Novel]]''
*''[[Halo: Uprising]]''
*''[[Halo Wars: Genesis]]''
*''[[Halo: Helljumper]]''
*''[[Halo: Blood Line]]''
*''[[Halo: Fall of Reach]]''
**''[[Halo: Fall of Reach - Boot Camp|Boot Camp]]''
**''[[Halo: Fall of Reach - Covenant|Covenant]]''
**''[[Halo: Fall of Reach - Invasion|Invasion]]''
{{col-3}}
*''[[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 (short story)|Palace Hotel]]''
**''[[Human Weakness]]''
**''[[The Impossible Life and the Possible Death of Preston J. Cole]]''
**''[[The Return]]''
*''[[Halo Legends]]''
**''[[Homecoming]]''
**''[[Odd One Out]]'' {{C|Non-canonical appearance}}
**''[[Origins]]''
**''[[Prototype]]''
**''[[The Babysitter]]''
**''[[The Package]]''
*''[[Halo: Glasslands]]'' {{mo}}
*''[[Halo: The Thursday War]]'' {{mo}}
*''[[Halo 4: Forward Unto Dawn]]''
{{col-end}}

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

==Sources==
<references/>

{{Human-Covenant War}}
{{Humanwars}}
{{Covenantwars}}
[[Category:Human-Covenant War]]