Editing Halo universe

{{Status|RealWorld}}
{{Center|For other uses of the word "Halo", see [[Halo (disambiguation)]].}}
{{New content}}
[[File:Halo logo (2012-present).png|450px|center|The Halo 4-era Halo logo.]]
[[File:Halo 20 Year Celebration Artwork.jpg|300px|thumb|''Halo''{{'}}s 20-year anniversary artwork.]]
{{Quote|Halo is an epic journey to save humanity from a terrible menace.|[[Chris Carney]] on ''[[Halo 3 Legendary Edition]]: [[Seven|7]] [[7 Steps to World Domination|Steps To World Domination]]''}}
The '''Halo universe''' is the sprawling fictional universe in which all [[Halo (disambiguation)|mainline Halo media]] takes place. In the 26th century, [[human]]kind has [[Human colonies|colonized]] hundreds of worlds in [[Earth]]'s interstellar neighborhood, only to stumble upon a hostile alliance of aliens known as the [[Covenant]]. Motivated by the [[Hierarchs|Prophets']] promises of [[Covenant religion|ascension to godhood]] in the form of the eponymous [[Halo Array|Halos]], a series of ring-shaped superweapons built by the ancient race of the [[Forerunner]]s, the Covenant are bent on humanity's destruction. With the apocalyptic [[Human-Covenant War]] concluded, members of both sides are faced with an uncertain future in a politically complex environment of numerous different factions and affiliations, while ancient Forerunner entities and technologies continue to involve themselves with the galaxy's affairs.

It is this universe where the Halo video game series: ''[[Halo: Combat Evolved]]'', ''[[Halo 2]]'', ''[[Halo 3]]'', ''[[Halo Wars]]'', ''[[Halo 3: ODST]]'', ''[[Halo: Reach]]'', ''[[Halo: Combat Evolved Anniversary]]'', ''[[Halo 4]]'', ''[[Halo: Spartan Assault]]'', ''[[Halo 2: Anniversary]]'', ''[[Halo: Spartan Strike]]'', ''[[Halo 5: Guardians]]'', ''[[Halo Wars 2]]'', and ''[[Halo Infinite]]'' take place. In addition to the games, a number of [[Halo novels]] and other media including [[:Category:Audio dramas|audio dramas]], [[:Category:Comics|comic books]], [[:Category:Tabletop games|tabletop games]], [[:Category:Cinematics|films]] and an [[Halo Legends|anime collection]] have been released. The media beyond the game series expands into the Halo universe timeline before and after the events of the games, as well as running concurrently with the games' timeline.

==Primary factions==
In the Halo universe, there are many factions, political groups, races, planets, and species. The main factions are as follows:

===United Nations Space Command===
[[File:UNSC insignia (post-war).png|thumb|150px|The emblem of the UNSC.]]
{{Main|United Nations Space Command}}
In the 26th century, most of humanity is ruled by the [[Unified Earth Government]] (UEG). As most of the [[Category:Canon|canon]] material from the ''Halo'' universe is from the ongoing war we see the future mainly through the eyes of the UEG's military arm, the [[United Nations Space Command]] (UNSC). During the events of ''Halo 2'' and ''Halo 3'', the UNSC [[Battle of Earth|fought]] the Covenant over [[Earth]] in a last-ditch attempt to protect the human race. The events of ''[[Halo: Reach]]'' are fought defending the planet [[Reach]], the UNSC's former military headquarters.

The UNSC was formed by the [[United Nations]] when overpopulation on [[Earth]] and conflict in the [[Sol System]] started becoming a severe problem in the early 22nd century. In the wake of the [[Interplanetary War]] in the 2160s, the UNSC became the military and space exploratory arm of the newly-established Unified Earth Government. After the emergence of the Covenant threat, the UNSC was given power over the UEG and its colonial governing agency, [[Colonial Administration Authority]], although the civilian government was formally returned its power after the war.

Run by [[UNSC High Command|HIGHCOM]], the UNSC is Earth's premiere defense against external threats. The [[UNSC Navy]] houses the divisions of [[UNSC Marine Corps|Marines]] (including the [[Orbital Drop Shock Trooper]]s), the [[Office of Naval Intelligence]] (ONI), and the [[UNSC fleet|fleet]]. The [[United Nations Space Command]] armed forces includes the [[UNSC Army]], the [[UNSC Air Force]], and [[Spartan Operations]], along with the Navy and Marines. Originally designed to keep the peace between neighboring planets and star systems, when certain [[Insurrectionist|rebellious factions]] began to present a problem in the late 2490s, the UNSC was forced to police its colonies to keep privateers and [[Space piracy|pirates]] from raiding them.

There are several breakaway factions opposed to UNSC and the Colonial Administration Authority as well, collectively known as [[Insurrectionist]]s.
{{clear}}

===Swords of Sanghelios===
[[File:Swords of Sanghelios symbol.png|thumb|150px|left|The Swords of Sanghelios' symbol.]]
{{Main|Swords of Sanghelios}}
The Swords of Sanghelios is a splinter faction of the Covenant formed by the [[Arbiter]] [[Thel 'Vadam]] and [[Shipmaster]] [[Rtas 'Vadum]], based upon an ancient Sangheili order. Formed from the [[Fleet of Retribution|initial alliance]] out of desperation with their former human enemies, the UNSC, they played a key role in ensuring the salvation of the galaxy and start a new era of relative peace alongside the UNSC.

Facing civil war after the end of the Human-Covenant War, the Swords became a major faction within the galaxy's political and military state. Alongside the UNSC they shared the [[Joint Occupation Zone]]s, research and monitoring stations on the Halo rings as well as MJOLNIR armor. Much of the Swords' trouble came from the [[Servants of the Abiding Truth]] and [[Jul 'Mdama]]'s emerging [[Jul 'Mdama's Covenant|Covenant faction]], both directly and indirectly caused by the Office of Naval Intelligence which sought the destabilization of the Sangheili race.

Ruled by a large council of [[kaidon]]s, the Swords of Sanghelios attempt to bring peace and unity to Sanghelios, the Elite homeworld, as well as returning the old values and traditions of Sangheili past. With their UNSC allies, they are succeeding in creating a new era of peace.
{{clear}}

===The Covenant===
[[File:Covenant LogoHD.png|thumb|150px|The Covenant's symbol.]]
{{Main|The Covenant}}
Originally formed by as an alliance between two species; the Prophets ([[San'Shyuum]]) and the Elites ([[Sangheili]]), the Covenant was a theocratic hegemony of multiple alien species. The name "Covenant" is based on the [[Writ of Union|binding Covenant]] formed between the two races, when the Sangheili promised to defend the San'Shyuum as they searched for the "Sacred Rings" ([[Halo Array]]) which are said to start the "[[Covenant religion|Great Journey]]", a term that the Prophets use to explain the disappearance of their Gods, the Forerunner race. The quest of the entire Covenant, the Great Journey is the basis of all of their worship. As the Covenant Empire grew over a millennium, more species were enslaved to their cause, although, up until the [[Great Schism]], none of them were quite as important to the Prophets as the Elites.

At first, the Covenant were mostly held together by a need to survive, but as their society advanced, so did their technology, culture and religion. Now the polytheistic Covenant control a large part of the Orion Arm of the Milky Way galaxy and their society is a complicated caste system, with the Prophets still on top, governing the Covenant along with the Elites. The Covenant is a theocracy, based on a prophecy about the Sacred Rings and the Great Journey. The actual context of this prophecy is based on the notion that the Forerunners were so advanced that they had found a way to propel themselves to godlike status using their technology. To oppose this, a parasitic race known as the Flood attacked the Forerunners and attempted to stop the activation of this technology. Before the Flood could stop them, the Forerunners activated the Halo Array, and ascended to godhood. The Covenant design is to find the Halos, and use it to propel themselves to godliness as well.

The three leading Prophets [[Prophet of Truth|Truth]], [[Prophet of Mercy|Mercy]], and [[Prophet of Regret|Regret]] who were the [[Hierarchs]] of the Covenant, wanted to destroy humanity due to the threat they pose to their religion: if humankind really are the Forerunners' heirs, then all that the Covenant believe in is false. Not wanting the truth about the humans to get out, the rest of the Covenant have been told that humanity is a direct affront to the Forerunner, much like the Flood in goal, so must be exterminated if the Great Journey is to be completed.

===Covenant remnants===
{{Main|Covenant remnants|Jul 'Mdama's Covenant|Banished}}
After the destruction of the original Covenant in the concluding events of the Human-Covenant War, the former member species fragmented into [[Covenant remnants|many factions]] with varying goals, many of them still hostile to humanity as well as each other.

===The Flood===
[[File:H Evol - Mona Lisa Flood Combat Forms.png|thumb|250px|[[Flood]] forms aboard the ''[[Mona Lisa]]''.]]
{{Main|Flood}}
'''The Flood''' (called '''The Parasite''' by the Covenant) is a species of virulent, parasitic organisms that thrive by consuming other sentient life of sufficient biomass, no matter where in the universe, thus leading Forerunners to the creation of the Halo Array. The Flood appears to be a hive or communal mind, existing in several stages that eventually lead into the creation of a central intelligence known as the [[Gravemind]].

The Flood grow and reproduce via the assimilation of other beings, utilizing corpses and acquiring any biomass (including both animal and plant) in order to spread. They are incapable of sexual reproduction, instead they fester inside a host until a certain time period, after which they explode and many new Flood are given off. Once a Gravemind is formed however, the Flood advance to a stage where they no longer require hosts for this, only biomass and calcium, which they require to feed on, and to build bodies with. Once they have advanced, they create hives which can produce thousands of Flood inside large pustules on walls and other surfaces, which act as incubators. During this stage, the Flood are able to build their own life forms using captured biomass and calcium deposits. The Flood continue in this fashion recurrently until either everything is devoured, or until they are stopped, the former usually occurring.

In modern times, little is known about their origin, except that they arrived from [[Large Magellanic Cloud|another galaxy]] and fought both [[prehistoric human civilization|prehistoric humans]] and Forerunners, eventually defeating the latter. The Forerunners discovered and then fought them until they were overwhelmed after centuries of war. Faced with the Flood spreading throughout the galaxy and consuming every sentient being, the Forerunners created seven artificial rings called the [[Halo Array|Halos]], galactic superweapons in the shape of enormous rings, to contain and hopefully stop the Flood from ever spreading. The point of the rings was to wipe out all sentient life, thus starving the Flood of the sufficient biomass required for them to continue spreading. Through their own interpretation of Forerunner artifacts, the Covenant believed these rings were actually devices that allowed the Forerunner to transcend this plane of existence into godlike state, and thus they seek to do the same by activating them once more, not realizing they would inadvertently wipe out all sentient life in the galaxy if they were to be successful in doing so.

Although it seemed the plan had been successful at eliminating the Flood threat, samples of the organism kept on the rings for study were released on at least two of the installations through accidental means, putting the galaxy once again at risk of complete destruction by the parasite.

===The Forerunners===
[[File:Main-Forerunner.png|thumb|150px|The Eld, a iconic Forerunners symbol associated with the [[Mantle|Mantle of Responsbility]].]]
{{Main|Ecumene}}
Once the dominant civilization in the [[Milky Way]], the Forerunners reached unparalleled technological advancement over 100,000 years before the Human-Covenant War. Believing to be charged by the mysterious [[Precursor]]s with protecting less advanced civilizations in the galaxy, they stumbled upon the Flood and fought a [[Forerunner-Flood war|three-hundred-year long war]] to stop the genocidal parasitic species from overrunning the galaxy. When it looked as if they were going to fail at that task, they built and activated the Halo Array - sterilizing the entire galaxy of sentient life including themselves, starving the Flood into submission, and [[Conservation Measure|repopulating the galaxy]] again with those few species saved from extinction.<ref name="origins">'''Halo: Legends''', ''Origins''</ref> 

All that remains now of the Forerunners are the ruins of their ancient temples and cities, a few scattered pieces of functional technology, and their automated combat and maintenance constructs. Their technological brilliance, combined with a garbled version of the Halo activation, led to the Covenant's religion revering the Forerunners as deities, and that this state could be achieved again by activating the Halos. In turn, these attempts led to the Human-Covenant War, and the eventual secession of the Sangheili and their alliance with humanity to stop the Covenant.{{clear}}

===Insurrectionists===
[[File:HM Icon Insurrectionist.png|thumb|left|100px|An Insurrectionist emblem.]]
The Insurrectionists are various rebel groups opposed to the rule of the UNSC throughout human space who seek the colonies' liberation from the Unified Earth Government's influence. Following the rapid volumetric growth of the region of space controlled by the human race throughout the 25th century, the UEG found it increasingly difficult to maintain its hold over the Outer Colonies, hundreds of which were scattered across exceedingly large swathes of space. By 2490, the Outer Colonies surpassed the core worlds in number by several hundred. Despite their more discrete composition, the Outer Colonies proved an ample breeding ground for a strong nationalist sentiment among their citizens which in turn led to their perceiving the Earth government—and the UNSC which imposed its will—as a draconian outside force. In 2513, the UNSC initiated [[Operation: TREBUCHET]], one of the largest operations in UNSC history; spanning ten years and costing hundreds of thousands of lives, the goal was to root out the Insurrectionists and impose order in the Outer Colonies. Following the Covenant attack on Harvest and the onset of the Human-Covenant War in 2525, Operation: TREBUCHET was put on halt by the UNSC. Insurrectionist activity as a whole, while not completely gone, died down during the Covenant War.

After the end of the Human-Covenant conflict, many insurrectionist movements such as the [[United Rebel Front]] which had ceased their operations during the war began to resurface. A number of colonies refused the offer of peace and cut all ties with the UNSC, which, according to them, had abandoned them during the war. Of major significance in the post-war era was the rise of the [[New Colonial Alliance]], founded by rogue UNSC Admiral [[Mattius Drake]], which in early 2553 attempted to hijack the newly-commissioned {{UNSCShip|Infinity}}.

{{Clear}}

==Technology==
{{Center|For more detailed summaries of each faction's technologies, see [[Human technology]], [[Covenant technology]], and [[Forerunner technology]].}}
===Transport===
[[File:Seperatist fleet ark.jpg|thumb|250px|The Sangheili assault carrier ''[[Shadow of Intent]]'' using Slipspace technology to travel.]]
*[[Slipstream space|Slipspace]] is the primary method of faster-than-light travel in the ''Halo'' universe. Humans have not exacted the science of Slipspace jumping, and can often end up hundreds of thousands of miles away from where they want to be, and therefore they work to be inexact, so as not to end up somewhere like the middle of a planet. The Covenant had worked a way around this, as they can pinpoint jump anywhere in the galaxy, even maintaining their formation. The Forerunners had a superior understanding of slipspace technology, being able to create [[Slipspace bubble|technologies]] which allow for manipulation of space-time through slipspace. One of many technologies created by the Forerunners is [[slipspace translocation]], allowing near-instantaneous transit over short distances.
*Wheeled contrivances similar in appearance to today's vehicles are used by the UNSC. However, the Covenant prefer to use [[anti-gravity technology]] assumed to be based on Forerunner technology.

===Artificial intelligence===
*[[Artificial intelligence|AIs]] work at superior speeds and with greater efficiency than biological beings; helping with [[astrogation]], maintenance, managing, and even battle. Human AIs are grouped into two major categories; [[Dumb artificial intelligence|"dumb"]] and [[Smart artificial intelligence|"smart" AIs]]. Dumb AIs are essentially powerful computer programs, which are incredibly intelligent within their programmed fields whether that be battle strategy, or maintaining plantations on [[human colonies]]. Smart AIs, which are created by [[Cognitive Impression Modeling|scanning]] the neural patterns of a human brain, are brilliant and have no limit to their imagination or intelligence other than that of their maximum storage capacity. However, they have a limited lifespan of roughly seven years before they enter a state known as [[rampancy]], which manifests as behavior comparable to human insanity.
*Due to their rigid beliefs, the Covenant only use AI constructs with only the bare minimum in every respect, only capable of piloting ships and have placed a ban on sentient AIs, which they refer to as [[associated intelligence]]s.

===Weapons and armor===
*While the UNSC still uses conventional weapons to a great degree, several innovations have been made. Standard armament on UNSC warships includes both conventional and nuclear missiles, guns of varying sizes, and perhaps most notably, the [[Magnetic Accelerator Cannon]], a type of [[Wikipedia:Coilgun|coilgun]] capable of delivering metallic projectiles at immense speeds. The UNSC also possesses a handful of [[directed energy weapon]]s, including the man-portable [[M6 Grindell/Galilean Nonlinear Rifle|M6 G/GNR]] anti-vehicle [[laser]].
*Most Covenant weapons are [[plasma weaponry|plasma-based]], from their [[Plasma turret|starship weapons]] to the smallest [[Type-25 Directed Energy Pistol|infantry arms]]. Several laser-based weapons are also in use, as well as weapons whose methods of operation are wholly unknown.
*[[Energy shielding]] technology, originally developed by the Forerunners, is featured on most Covenant starships, installations and is integrated in some infantry armor systems as well. During their war with the Covenant, the UNSC have reverse-engineered this technology, though its applications are nowhere near as widespread as in the Covenant.

===Other===
*[[Artificial gravity]] is common on both UNSC and Covenant starships. While some UNSC vessels possess rotating centrifuges to enable this, both factions have developed technology capable of generating artificial gravity through some unknown mechanism. [[Anti-gravity technology]] is also used by both factions on their starships, allowing them to descend and hover in a planet's atmosphere.
*[[Superluminal communications|Instantaneous communication]] over interstellar distances is available to all major factions, with humanity being the most recent civilization to discover a form of this technology.

==History==
===Prehistory===
{{Main|The Forerunner Saga|Halo: Cryptum|Halo: Primordium|Halo: Silentium}}
[[File:Forerunner Saga compilation.png|thumb|250px|''[[The Forerunner Saga]]'' by [[Greg Bear]] chronicles the ancient history of the ''Halo'' universe.]]
Over ten million years [[10,000,000 BCE|ago]], an advanced civilization known as the [[Precursor]]s controlled the galaxy. Having reigned for billions of years and reached the pinnacle of technological advancement, they seeded the galaxy with life and created many species, including humans and Forerunners. The Precursors held the [[Mantle|Mantle of Responsibility]], the guardianship of all life in the galaxy. They eventually decided to give the Mantle to one of their creations and they initially selected the Forerunners. However, the Precursors changed their minds on handing it to them - tasking humanity with it. The Forerunners, enraged by their creators' favoring of humanity over themselves, rebelled against the Precursors and [[Forerunner-Precursor war|wiped them out]] almost entirely. Some Precursors survived by reducing themselves to dust that, although meant to regenerate their original forms in time, was corrupted over the passage of millions of years and would eventually manifest itself in a completely new form - the parasitic [[Flood]].<ref name="silentium">'''[[Halo: Silentium]]'''</ref> Meanwhile, the Forerunners would adopt the Mantle to themselves and rise to become the dominant civilization in the galaxy, directing the evolution and development of other species as they saw fit. Records of the truth about the Precursors were lost over time and faded into legend; ten million years after the destruction of the Precursors, Forerunners simply believed that their creators had disappeared and given them the gift of the Mantle.<ref name="cryptum">'''[[Halo: Cryptum]]'''</ref>

Early humanity first arose on their homeworld Earth, then known as "Erde-Tyrene" and mastered interstellar travel, eventually becoming a [[Prehistoric human civilization|prosperous interstellar empire]] based on the planet [[Charum Hakkor]]. They also [[Human-San'Shyuum alliance|allied]] with the [[San'Shyuum]] species, who would become the ruling caste of the Covenant thousands of years later. Around [[107,445 BCE]], however, humanity stumbled upon the nascent form of the [[Flood]] parasite near the galaxy's edges. Hundreds of systems were lost to the parasite in [[Human-Flood war|a conflict]] between the humans and the Flood as humans desperately sterilized any infested world while securing new colonies for their dwindled populations in the borders of the Forerunner ecumene. Humanity's aggressive expansion and the perceived violations of the [[Mantle]] eventually prompted the Forerunners to take action and [[human-Forerunner wars|go to war]] against humanity. Despite being forced to fight a two-front war against the Flood and the Forerunners, humanity evidently drove the Flood out of the galaxy. However, the Forerunners, led by the [[Promethean]] supreme commander known as the [[Ur-Didact|Didact]], eventually emerged victorious over humanity after defeating their last stronghold on Charum Hakkor.{{Ref/Reuse|cryptum}}

Following the war in approximately [[106,445 BCE]], the Forerunners dismantled humanity's civilization, regressing them into a [[Technological Achievement Tiers|Tier 7]] species. The remaining humans exiled to their homeworld Earth, where the supreme Forerunner [[Lifeshaper]], known as the [[Librarian]], tended to them and slowly guided them toward developing [[Erde-Tyrene civilization|a primitive civilization]]; unlike most Forerunners, the Librarian saw potential in humanity to eventually become the Forerunners' successors.{{Ref/Reuse|cryptum}}

Circa [[97,745 BCE]], the Flood resurfaced to challenge the Forerunners. Weakened by their struggle with humanity as well as major internal strife, the Forerunners were easy prey to the resurgent Flood. For three hundred years, the parasite claimed numerous Forerunner planets and systems, until virtually overrunning the entire ecumene. As a final resort, the Forerunners - specifically, an individual known as the [[IsoDidact]] - [[Great Purification|fired]] the [[Halo Array]], a network of superweapons which eradicated all neurologically complex life in the galaxy and subsequently caused most Flood to die out. While life was [[Conservation Measure|re-seeded]] into the galaxy by the Forerunners, the few surviving Forerunners themselves would go into self-imposed exile and not return, passing their Mantle down to its rightful inheritors - humanity.{{Ref/Reuse|silentium}}

===Rise of the Covenant===
{{Main|History of the Covenant|Halo: Broken Circle}}
Dozens of millennia after the disappearance of the Forerunners, two original species of the Covenant, the San'Shyuum and the Sangheili, spent years locked in a bitter war over the control of the remains of the Forerunners. The Prophets wished to use the technology to search and explore the galaxy, but the Elites believed such usage to be a desecration of their holy artifacts. As the devastating war ravaged both species, the Elites saw that the only way for them to win was to do the exact thing they opposed; use their own Forerunner technology to adapt and befit their vessels. Eventually, the two species formed an alliance which was formalized with the [[Writ of Union]]. Over the following centuries, many species would be absorbed under the power of the Covenant hegemony, and thus conscripted into the search for Forerunner relics, and later the attempt to eradicate the human race.

===Origin of the UNSC===
{{Main|History of the UNSC|Human colonies}}
In the late 21st and early 22nd centuries, humanity colonized several worlds in the [[Sol system|Solar System]], including [[Luna|Earth's moon]], [[Mars]], the [[Jovian Moons]], and several [[asteroid]]s. In the years [[2160|2160-2200]], various [[National government|governments]] and factions fought for control of Earth and its first colonies. As overpopulation and unrest on Earth mounted, new political movements formed including the Jovian [[Frieden]] and [[Koslovics]] led by [[Vladimir Koslov]], resurgences of [[fascism]] and neo-[[communism]] which waged the [[Interplanetary War|Interplanetary]], [[Rain Forest Wars]] and [[Argyre Planitia Campaign|Mars]] clashes and were defeated by the victorious United Nations Space Command. The Unified Earth Government was established following the conflicts, emerging as the rulers of most of humanity who now faced the problem of overpopulation, famine and economic instability caused by the wars.

In the late 23rd century, humanity developed the [[Shaw-Fujikawa Translight Engine]], a device which enabled faster-than-light travel through a domain of alternate space-time known as [[slipstream space]]. The first extrasolar colony ships went on to colonize worlds in nearby systems within the next decades. The [[Inner Colonies]], as they later came to be known, would be considered the elite, in contrast to the more remote and less wealthy [[Outer Colonies]], formed over the course of the 2400s.

In the 2490s, with over 800 settled worlds across the [[Orion Arm]] of the [[Milky Way]] galaxy, humanity's "Golden Age" of expansion was coming to an end. Gradually, the Outer Colonies had became more isolated and unstable. Their populations had widely varying loyalties to Earth, and taxes and trade restrictions set up by the UEG's colonial governing agencies caused dissent against the Earth government. This eventually led to the [[Insurrection]], an undeclared civil war between the UNSC and the various [[Insurrectionist|rebel groups]] that rose up against it in the Outer Colonies.

[[File:HTFOR Cover 2010 edition.jpg|thumb|150px|The book, ''Halo: The Fall of Reach'', details the origins of the SPARTAN-II program and serves as a prequel to ''Halo: Combat Evolved''.]]
====Insurrection and the SPARTAN-II project====
{{Main|Halo: The Fall of Reach|Insurrection|SPARTAN programs}}
By [[2517]], the UNSC was facing extremely low morale due to [[Space piracy|piracy]] and the ongoing Insurrection. In order to remove the rebellion without a significant sacrifice of human life, the [[Office of Naval Intelligence]] decided to move forward with the [[SPARTAN-II program|SPARTAN-II]] project, headed by Dr. [[Catherine Halsey]]. Seventy-five physically and mentally gifted children were abducted at the age of six, replaced by [[Flash cloning|flash-clones]] in a black operation, and drafted into the UNSC. The children went through [[SPARTAN-II training|rigorous training]] and [[SPARTAN-II augmentation procedures|physical augmentations]] through surgical and medical means. Code-named SPARTANs, these supersoldiers were trained for a life of battle, and would become a great asset against the Covenant in both frontline and covert operations; the Spartans specializing in both.<ref name="TFoR">'''Halo: The Fall of Reach'''</ref>

===The Human-Covenant War begins===
{{Main|Halo: Contact Harvest|Halo 4: Forward Unto Dawn|First Battle of Harvest}}
On [[2525#February|February 3, 2525]] the UNSC colony of [[Harvest]] detected an unknown object on its long-range radar. The object was constructed with materials unlike anything seen before. All contact with Harvest was lost soon after. Ships sent to the system revealed that it had been totally destroyed by a new alien group called the Covenant. A battle group was sent but was defeated by the technologically superior Covenant ships. Only one ship made it back, the {{CMAShip|Heracles}} returned with a message that was sent to them, pre-translated, saying, "Your destruction is the will of the gods, and we are their instrument".{{Ref/Reuse|TFoR}}

The novel ''[[Halo: Contact Harvest]]'' further details the events that transpired at Harvest and the Covenant leadership's underhanded scheme surrounding the beginning of the war: humans were discovered to be [[Reclaimer|living heirs]] to the Covenant's gods, the Forerunners, forming a concrete threat to the Prophets' authority as well as the very foundation of the [[Covenant religion|their religion]]. Rather than reveal the truth to the Covenant at large, the new triumvirate of [[Hierarchs]] call for the complete destruction of humankind, under the pretense that humans had committed unforgivable offenses against their gods.

In response to the destruction of Harvest, [[Preston Cole|Vice Admiral Preston Cole]] mobilized the [[Battle Group X-Ray|largest space fleet]] in human history to retake Harvest. The fleet defeated the Covenant ships at Harvest in [[2531]] but at great cost with Cole losing two-thirds of his fleet. The highly advanced Covenant shielding and weapons systems simply outclassed anything they had and so began the slow destruction of the human race. One by one the UNSC colonies were lost until by [[2535]], virtually all of the [[Outer Colonies|Outer Colony]] worlds had been destroyed by the Covenant and the [[Inner Colonies]] were being invaded. [[United Nations Space Command Emergency Priority Order 098831A-1|The Cole Protocol]] was established by military order: all human vessels must ensure that Covenant forces do not find Earth. To achieve this whenever they must jump out of a battle, they must do so to a randomized vector that points away from any human worlds.{{Ref/Reuse|TFoR}}
====Apex Site====
{{Main|Halo Wars: Genesis|Halo Wars|Harvest Campaign|Battle of Arcadia|Battle of the Etran Harborage}}
[[File:HaloWarsWithTeen.jpg|thumb|150px|''Halo Wars'' is set twenty one years before the events of ''Halo: Combat Evolved'' and centers around the crew of the ''UNSC Spirit of Fire''.]]
On, [[2531|January 3, 2531,]] the UNSC [[UNSC Spirit of Fire|''Spirit of Fire'']] is sent to Harvest to assist the crippled [[UNSC Prophecy|UNSC ''Prophecy'']]. When the ''Spirit of Fire'' arrives, the Cole Protocol is then enacted on the ''Prophecy'', in so ensuring its destruction. While scientist [[Ellen Anders]] and captain [[James Cutter]] discuss the northern regions of Harvest, they realize the Covenant might be after something that is specifically there. Cutter sends Sergeant [[John Forge]] to assemble a team and investigate. Forge and his team soon find the presence of a [[Relic (location)|Forerunner relic]], and that the Covenant are after it. After clearing a way through Covenant forces, the UNSC's forces enter the relic and find out where the Covenant have been pointed to— [[Arcadia]]. Following the Covenant fleet there, ''Spirit of Fire'' soon gets entangled in an evacuation process, but they do safely extract some civilians from the colony. After a few more battles, Anders gets taken by the [[Arbiter]], [[Ripa 'Moramee]]. The chase continues as the ''Spirit of Fire'' follows the Covenant fleet to [[Trove]].

The search for Ellen Anders starts while it is revealed to both factions that the Flood has taken over the exterior of the shield world. ''Spirit of Fire'' enters the shield world's inner shell, looking for Anders, who is now being forced to activate a once-hidden [[Sojourner-class dreadnought|Forerunner fleet]] for the purposes of being reverse-engineered into the Covenant naval force for easy extermination of the human species. Anders then escapes using a [[Slipspace translocation|translocation device]] and then conveniently links up with the UNSC again. This news reaches ''Spirit of Fire'', which then has her FTL drive extracted for the purpose of destroying the Shield World's sun, therefore denying the Covenant the fleet it wants, which would lead to the extinction of the human race. This plan works out, but at the cost of Forge's life, who heroically stays behind to detonate the FTL drive. Without an FTL drive, and the long expected journey home most likely going to take years or decades, the Spirit of Fire's crew enters into cryonic storage, now drifting in space until contact is made.
[[File:Halo Reach (Standard with ESRB).png|thumb|150px|''Halo: Reach'' is set during the fall of the UNSC fortress world Reach.]]

====The Fall of Reach====
{{Main|Halo: The Fall of Reach|Halo: Reach|Fall of Reach}}
By [[2552]], many of humanity's Inner Colonies had been destroyed by the Covenant. The UNSC leadership assembled a Spartan-II strike team, at the human command base on the planet Reach. In a move of desperation, the UNSC planned to launch a targeted strike against the [[Hierarchs|Covenant leadership]]. This plan was abandoned when the Covenant launched a surprise attack on the world of Reach.{{Ref/Reuse|TFoR}}

During this battle, most of Reach is overrun and glassed, and the human fleet obliterated. One of the Spartans, [[John-117|Master Chief Petty Officer John-117]], is able to escape on the ship ''[[UNSC Pillar of Autumn|Pillar of Autumn]]'' along with her crew. In fleeing the Covenant fleet, the ''Autumn''<nowiki>'</nowiki>s onboard AI, [[Cortana]], uses a set of coordinates from a recently discovered Forerunner artifact that leads them straight to the Forerunners' [[Installation 04]].{{Ref/Reuse|TFoR}}

In the game ''[[Halo: Reach]]'', the Spartans of [[Noble Team]] defend Reach against the Covenant invasion, most of them sacrificing their lives in the process. At the finale, they are given the task of transporting a fragment of Cortana housing critical data to the ''Pillar of Autumn''. [[Noble Six]] holds off the Covenant long enough for the ''Autumn'' to escape, indirectly enabling humanity's survival in the war.

====Alpha Halo====
{{main|Halo: Combat Evolved|Halo: The Flood|Battle of Installation 04}}
[[File:Halo Combat Evolved cover.png|thumb|150px|left|The first game, ''Halo: Combat Evolved'', takes place around and on Alpha Halo.]]
Three weeks after escaping Reach, the ''Pillar of Autumn'' exits Slipspace to find a mysterious [[Installation 04|ring-shaped space station]] orbiting the gas giant [[Threshold]]. The ring, referred to by the Covenant as "[[Halo Array|Halo]]", is an artificial construct that is teeming with life. A [[Fleet of Particular Justice|Covenant fleet]], however, is also present, and a subsequent battle heavily damages the ''[[UNSC Pillar of Autumn|Pillar of Autumn]]'' and the ship crash lands onto Halo.

The first Halo game begins in earnest with the Master Chief's escape from the ''Autumn'', and continues upon landing. The first levels of the game deal with an attempt to reach Halo's control center to uncover its purpose. It is soon discovered that the Covenant have accidentally and unwittingly released the [[Flood]], a parasitic alien species. The Flood then sweep across Halo and devastate human and Covenant forces positioned on it. The release of the Flood prompts [[343 Guilty Spark]], an eccentric Forerunner AI, to try to activate Halo's defense system, a pulse weapon that, when fired, would wipe out all sentient life in the galaxy large enough to be hosts for the Flood. Technically, that installation only has a maximum effective radius of 25,000 light years, but the pulse would trigger other installations as well, effectively killing all intelligent life in the galaxy. This system is designed to stop the Flood from spreading through the universe if they escape confinement from Halo by the only way possible: starving the Flood of any life source that can sustain them.

Naturally, this would wipe out humanity as well, and so the final levels of the game revolve around the Master Chief's attempts to destroy Halo before it fires by self-destructing the ''Autumn''. Despite the abuse sustained during the space battle and the following crash the ''Pillar of Autumn'' remained intact, and was subsequently occupied by investigating Covenant forces and later by Flood.

Having manually triggered a destabilization of the power cores the Master Chief and Cortana commandeer a [[GA-TL1 Longsword|Longsword]] from one of the ''Pillar of Autumn's'' docking bays and achieve a safe minimum distance before the ''Autumn's'' drives explode, causing the ring-world to fragment.<ref>'''Halo: Combat Evolved'''</ref>
{{Clear}}

====First Strike====
[[File:Firststrike2.jpg|thumb|150px|''Halo: First Strike'' takes place between ''Halo: Combat Evolved'' and ''Halo 2''.]]
{{Main|Halo: First Strike|Operation: FIRST STRIKE}}
Occurring between ''Halo: Combat Evolved'' and ''Halo 2'', ''Halo: First Strike'' starts off with Master Chief and a few other survivors in space above the destroyed Halo. They capture the Covenant flagship ''[[Ascendant Justice]]'' and make their way back to Reach. When they arrive they find the entire planet ravaged; however, on a small patch of the surface left unscathed, it is discovered that Dr. Halsey and several Spartans who survived the fall of Reach have found a [[Menachite portal complex|Forerunner structure]] under ONI's [[CASTLE Base]]. There they find a [[Forerunner crystal|special artifact]] that warps space-time, before being retrieved by the UNSC forces aboard the ''Ascendant Justice'' along with other survivors, including [[Danforth Whitcomb|Vice Admiral Whitcomb]].

Cortana, now in control of the Covenant ship, docks with the damaged UNSC frigate ''[[UNSC Gettysburg|Gettysburg]]'' and combines their power, also allowing them to return to Earth without violating the Cole Protocol by bringing a potentially "bugged" Covenant ship with them. Damaged in a battle with pursuing Covenant ships, the ''Ascendant Justice'' travels to a [[Eridanus Secundus|hidden rebel base]] in the [[Eridanus system]] for repairs. The rebels agree to a truce with the UNSC forces, but the Covenant soon discover their location. In the ensuing chaos, Dr. Halsey abducts [[Kelly-087]] and flees into slipspace aboard the [[Jacob Jiles|rebel governor]]'s [[Beatrice|ship]]. Admiral Whitcomb grimly decides to leave the rebels to fend for themselves while the ''Ascendant Justice'' escapes.

The Master Chief and other Spartans discover a massive plot to attack Earth. They covertly attack and destroy a massive Covenant [[Unyielding Hierophant|refit and repair station]] along with an attack force many times larger than the one that attacked Reach. In doing so they lose the Covenant flagship; however, they save the ''Gettysburg'' and escape back to Earth with it.
{{clear}}
====Delta Halo====
[[File:Halo 2 cover.jpg|thumb|left|150px|''Halo 2'' takes place on Earth and around Installation 05 (Delta Halo).]]
{{Main|Halo 2|Battle of Earth|Battle of Installation 05|Great Schism|Halo: Broken Circle}}
''Halo 2'' starts with the beginning of a Covenant attack on Earth. John-117 begins on ''[[Cairo Station (station)|Cairo Station]]'', one of the three hundred [[Orbital defense platform|space defense platforms]] that orbit the planet. After repelling the Covenant [[Naval boarding|boarding parties]], the battle shifts to [[Battle of Mombasa|Earth's surface]]. During the battle, the [[Prophet of Regret]]'s carrier, ''[[Solemn Penance]]'', makes a Slipspace jump and the UNSC ship ''[[UNSC In Amber Clad|In Amber Clad]]'', with the Master Chief aboard gets swept up in the ship's wake in a desperate effort to follow it. The ''In Amber Clad'' is transported to the vicinity of another Halo ring - [[Installation 05|Delta Halo]] - on which they land. 

The game also follows an alternating story, viewed through the perspective of the [[Thel 'Vadam|Arbiter]], an Elite commander disgraced for his failure to prevent the first Halo's destruction. During a mission to quell [[Sesa 'Refumee's heretic faction|a movement]] regarded by the [[Hierarchs|Covenant leadership]] as heretical, the Covenant recover [[343 Guilty Spark]]. After their mobile capital, ''[[High Charity]]'', arrives at Delta Halo, the Covenant becomes embroiled in a power struggle discreetly engineered by the [[Prophet of Truth]], with [[Jiralhanae|Brutes]] usurping the role of the Elites, beginning an apocalyptic civil conflict known as the [[Great Schism]].

Meanwhile, a battle rages on Delta Halo's surface. Both the UNSC and the Covenant seek to obtain the Halo's [[activation index]] whilst being caught in a [[Battle of the Quarantine Zone|battle]] raging between the Halo's [[sentinel]]s and the [[Flood]], which has escaped containment. Both the Master Chief and the Arbiter eventually end up in the clutches of an entity known as the [[Gravemind]], the controlling intelligence of the Flood. With its own agenda in mind, the creature tasks the Master Chief and the Arbiter with stopping the Covenant from activating the Halo. The Spartan is sent to ''High Charity'' to stop the Prophet of Truth, while the Arbiter is transported to the vicinity of the Halo's [[control room]], where he discovers that the Brutes have betrayed his kind.

Confronting [[Tartarus]], the Chieftain of the Brutes, in the control room, the Arbiter learns the truth about the Halos from 343 Guilty Spark: the rings were built to prevent the Flood from spreading throughout the galaxy, and the Forerunners who built it were wiped out when they fired it as a weapon of last resort in the distant past. In spite of this, Tartarus activates the ring in preparation to fire, to bring about the Great Journey. Tentatively allied with the UNSC forces present, the Arbiter manages to defeat Tartarus and the activation index is removed before the Halo can fire. 343 Guilty Spark reveals that although the Index was removed before Delta Halo had time to complete its firing sequence, it sent signals to other Halos in the galaxy, putting them on standby mode. Now, they can be activated remotely from the Ark, whose nature or location is not revealed at this point.

''High Charity'' has fallen into chaos as a result of the Great Schism and an invasion by the Flood. The Prophet of Truth, intent on reaching Earth and the Ark, speeds toward the [[Forerunner Dreadnought]] in the heart of the city. With Cortana staying behind to momentarily delay the Dreadnought's launch, the Master Chief boards the Forerunner ship as it launches from the Covenant holy city, headed for Earth.
{{clear}}
[[File:Onyx cover.jpg|thumb|150px|Set mainly on the mysterious world of [[Onyx]], ''Halo: Ghosts of Onyx'' establishes the SPARTAN-III program.]]

====SPARTAN-III program and Onyx====
{{Main|Halo: Ghosts of Onyx|SPARTAN-III program|Onyx Conflict}}
''[[Halo: Ghosts of Onyx]]'', which tells the story of the events that occurred on the planet [[Onyx]], begins in [[2545]], with the [[SPARTAN-III Beta Company|Beta Company]] of [[SPARTAN-III program|SPARTAN-IIIs]] [[Operation: TORPEDO|deploying]] to a Covenant fleet refueling depot on [[Pegasi Delta]]. They proceed to destroy the facility, but due to unexpectedly heavy Covenant resistance, all but two of the three-hundred-strong Spartan company is wiped out. The only survivors, [[Tom-B292]] and [[Lucy-B091]], are revealed to be only twelve years old, and Lucy is traumatized and [[post-traumatic vocal disarticulation|rendered mute]].

In [[2531]], SPARTAN-II [[Blue Team]] [[Operation: SMOKING ACES|raid]] a rebel base on planet [[Victoria]] to recover stolen nuclear warheads. The team is nearly captured by a rebel ambush, but is saved by the timely, intuitive intervention of [[Kurt-051]]. Some time afterward, [[Colonel]] [[James Ackerson]] presents the top leadership of ONI with his proposal for a new Spartan project. They agree that the SPARTAN-II program is prohibitively expensive and that a more streamlined, "disposable" breed of Spartans must be trained for high-risk operations. Kurt-051 and [[Franklin Mendez|SCPO Mendez]] are brought in to train the new generation of Spartans on the classified planet of [[Onyx]].

Over twenty years later, in [[2552]], [[Team Saber|Teams Saber]], [[Team Katana|Katana]], and [[Team Gladius|Gladius]] of [[SPARTAN-III Gamma Company|Gamma Company]], the third S-III generation, conduct a training exercise when they run into previously undiscovered [[Onyx Sentinel|Forerunner Sentinels]]. Through a series of events, a [[Joyous Exultation Covenant|group]] of Sangheili-led Covenant discover the existence of Onyx and the potential Forerunner treasures within, prompting the UNSC to dispatch reinforcements to the planet. Meanwhile, Dr. Halsey, having disappeared on a quest of her own during the events of ''First Strike'', arrives at Onyx and joins with the UNSC forces there.

Pursued by the Sentinels and the Covenant, the human force discover an ancient Forerunner city, where they learn that the entire planet is an artificial construct. Fighting off determined Covenant pursuers, they press on into the heart of the planet. Entering a slipspace rift in Onyx's core, they find themselves alone in a vast [[Dyson sphere]] habitat. Kurt-051 stays behind to activate a pack of [[FENRIS nuclear warhead|nuclear warheads]], sacrificing himself to halt the Covenant pursuers. Subsequently, Onyx itself disintegrates, and is revealed to be composed of billions of Sentinels.
{{clear}}

====Battle for Earth====
[[File:Halo 3 ODST Cover.png|thumb|left|150px|''[[Halo 3: ODST]]'' takes place in New Mombasa, Earth.]]
{{Main|Halo 3: ODST|Battle of Mombasa}}
''Halo 3: ODST'' tells the story of what happened after the Covenant slipspace jump in the port city of New Mombasa in ''Halo 2'', as seen from the eyes of the [[Rookie]], an [[Orbital Drop Shock Troopers|ODST]], and his squadmates.

Prior to the slipspace rupture in ''Halo 2'', a large number of ODSTs are destined to drop into the [[Solemn Penance|Covenant carrier]] that evaded Earth's orbital defenses. The drop is initiated, but the [[Unidentified Shock Trooper squad|ODST squad]] of [[Gunnery Sergeant]] [[Edward Buck]] is commandeered by his superior, and former love interest, [[Captain (Navy)|Captain]] [[Veronica Dare]] of the Office of Naval Intelligence to drop into the city of New Mombasa, as opposed to the Covenant carrier. The slipspace rupture causes the squad to scatter and land in different parts of the city.

The Rookie wakes about six hours later and must find his squad. He roams the night-time city, fighting off Covenant patrols and discovering, with the aid of the city's [[Superintendent]] AI, clues that allow him to discover the fate of his fellow squad mates (with each discovery putting the player into that squad member's place for a level). He then picks up on Captain Dare's distress signal. The Rookie fights his way into and through an [[New Mombasa Data Center|underground facility]] where they meet up, and continue to fight their way through a massive [[Drone]] hive (awakened by the earlier detonation of an [[ONI Alpha Site (location)|ONI building]] at the top of the shaft at the hands of [[Michael Crespo|Mickey]] and [[Taylor H. Miles|Dutch]]). They both fight their way to the Superintendent data core, and discover a Covenant [[Huragok|Engineer]], one of many biological supercomputers and unwilling assistants to the Covenant, whom has taken apart the Superintendent's memory core and possesses vital information on the Covenant which could turn the tide of the war. 

They, along with Buck, fight their way down the city's [[New Mombasa Waterfront Highway|Waterfront Highway]], where they witness the Covenant begin to glass parts of the city. They hold off against waves of Covenant until Mickey, Dutch and [[Kojo Agu|Romeo]] arrive to pick them up. They arrive just before the Covenant prepare to glass their previous position, actually discovered to be an excavation project. They manage to escape just in time, only to realize that the Covenant has found what they were looking for.
{{Clear}}
====End of the war====
{{Main|Halo 3|Battle of Kenya|Battle of Installation 00}}
[[File:Halo3coverart.JPG|thumb|150px|''[[Halo 3]]'' takes place on Earth and the Ark.]]
''Halo 3'' takes place two weeks after the end of ''Halo 2''. The Covenant have all but obliterated human resistance on Earth, and have committed most of their forces in East Africa, near the ruins of Mombasa. Marines and the Arbiter [[Recovery of John-117|recover]] Master Chief John-117 after he jumps from the [[Forerunner Dreadnought]] as it entered Earth's atmosphere, and they all make their way back to the local UNSC base, [[Crow's Nest (location)|Crow's Nest]]. The Master Chief [[Attack on Crow's Nest|defends the base]], ultimately destroying it with a [[Improvised UNSC bomb|bomb]]. He regroups with a small group of Marines and they rally scattered UNSC forces before [[Assault on the Tsavo Highway|assaulting]] the Covenant-held [[Tsavo highway (location)|Tsavo Highway]], clearing a path into [[Voi]].

It is revealed that a large Forerunner artifact has been dug up under the African desert by the Covenant, and the Prophet of Truth is planning to activate it. Presumably this is the Ark, so therefore this would activate the Halos, and so a [[Battle of Voi|hasty attack]] is set in motion by Lord Hood to destroy the Forerunner Dreadnought with a surprise aerial assault. Master Chief clears Voi of all Covenant anti-air units to clear the path for Lord Hood's frigates for an assault on the dreadnought. However, the assault on the dreadnought has absolutely no effect, and Truth activates the artifact all the same. A large portal is created above the artifact, into which the Covenant forces disappear. Soon after, a [[unidentified Flood-captured battlecruiser|derelict Covenant cruiser]] appears out of Slipspace, and crashes nearby, infested with Flood.

The Master Chief and the Arbiter make their way toward the ship, and as they near its location, an [[Fleet of Retribution|Elite-controlled fleet]] appears, striking up an alliance with the humans and helping rid the city of Flood. Master Chief enters the ship and retrieves a message from Cortana, warning that High Charity is heading to Earth, full of Flood. It is decided that only the frigate ''[[UNSC Forward Unto Dawn|Forward Unto Dawn]]'', the ship of [[Miranda Keyes]], along with the Elites, will go through the portal after Truth, and stop him from activating the rings, as well as finding the "solution" to the Flood that Cortana's message spoke of.

The human/Elite force arrives at [[Installation 00|the Ark]], and engage Truth's Brute fleet. Master Chief makes landfall and finds the [[Cartographer]] of the Ark, which leads him to the location of the remaining [[Covenant]] forces at the [[Installation 00 Citadel|Citadel]]. This leads to a trident strike at three [[barrier tower|shield generators]] guarding the Citadel at the heart of the Ark. Once all three generators have been deactivated, The Master Chief and the Arbiter breach the Citadel after Truth kills Miranda Keyes and forces [[Avery Johnson|Sergeant Major Avery Johnson]] to activate the rings. The Arbiter kills Truth, ending the Covenant, while the Master Chief deactivates the rings. The Gravemind then turns on them and sends a horde of Flood their way.

After the Master Chief and the Arbiter escape the Flood, they discover that a [[Installation 08|new Halo]] is being built to replace [[Installation 04]] which is nearly complete. The Master Chief decides that the only way to destroy the Flood was to activate the newly built Halo, which was out of range of the other installations, with Cortana. The Arbiter leaves to gather the surviving forces and get them ready to leave, and the Master Chief heads to the crashed ''High Charity'' to recover Cortana. After wading through tantamount to infinity of Flood, he recovers her and escapes to the new Halo with the Arbiter.

After fighting their way up to the top of the control room, the Master Chief and the Arbiter enter the control center, and attempt to activate the ring. However, 343 Guilty Spark attempts to stop the Chief and Johnson from activating the ring, saying that the charging sequence of the incomplete Halo will prove too much for the structure, and cause it to tear itself apart. In the fight, 343 Guilty Spark mortally injures Johnson, but fails at killing Master Chief, who destroys him with a [[M6 Grindell/Galilean Nonlinear Rifle|Spartan Laser]]. They succeed in activating the ring, however as expected, the installation begins to fall apart, and once more does Master Chief makes an attempt to escape Installation 04 in a Warthog. The two board the ''Dawn'', which then proceeds toward the portal. The ''Dawn'' heads into the portal just as Halo fires, which closes as it gets halfway through shearing the ''Dawn'' in half. 

Half of the ''Dawn'', as well as the Arbiter, crashes back on Earth, and [[Voi Memorial|a memorial service]] is held for those who perished in the Human-Covenant War, ending on the note of the Master Chief's death. However, unknown to the rest of humanity, the Master Chief survived and put himself into cryosleep, as Cortana activates a [[Emergency locator beacon|distress beacon]]. Adrift in space for years, the rear half of the ''[[UNSC Forward Unto Dawn|Forward Unto Dawn]]'' eventually hurtles toward a mysterious Forerunner planet, later to be known as [[Requiem]].

[[File:Glasslands cover.jpg|thumb|150px|''Halo: Glasslands'' is the first novel to be set in the post-war ''Halo'' universe.]]

===Post-war era===
{{Main|Kilo-Five Trilogy|Blooding Years|Halo: Spartan Assault|Halo: Initiation|Halo: Nightfall|Halo: New Blood|Halo: Hunters in the Dark|Halo: Last Light|Halo: Shadow of Intent}}
Following the end of the war, humanity begins to rebuild and achieves a number of technological breakthroughs with the aid of an increasing amount of discovered Forerunner artifacts. Despite the alliance with [[Arbiter]] [[Thel 'Vadam]], the political situation in the known galaxy remains volatile, with ONI concerned about reprisal on part of the now-divided Sangheili. A Sangheili group known as the [[Servants of the Abiding Truth]] push for an insurrection against the Arbiter and his forces, whom they consider to be blasphemous for colluding with humanity. In response to the growing strife among the Sangheili, ONI Commander in Chief [[Admiral]] [[Margaret Parangosky]] assembles a black operations team known as [[Kilo-Five]], which is assigned on a covert mission to sow discord between disparate Sangheili factions by any means necessary, as well as to arrest [[Catherine Halsey|Dr. Catherine Halsey]] once she has been located. In a concurrent storyline which directly follows that of ''Halo: Ghosts of Onyx'', Dr. Halsey, [[Franklin Mendez|SCPO Franklin Mendez]], and a group of [[SPARTAN-II program|SPARTAN-IIs]] and [[SPARTAN-III program|SPARTAN-IIIs]] look for a means of escape from a [[Forerunner]] [[Trevelyan|shield world]] locked in a [[Slipstream space|slipspace]] bubble in the remnants [[Onyx]]. While they are eventually recovered and the shield world is claimed by the UNSC as a research facility christened [[Trevelyan]], Admiral Parangosky has Dr. Halsey arrested and imprisoned as personal retribution.

With Halsey out of the picture, Kilo-Five has another growing priority in the rebel-leaning planet of [[Venezia]] which may present yet another threat to the UNSC. Meanwhile, the situation on Sanghelios escalates as [[Avu Med 'Telcam]] rallies the Servants of the Abiding Truth and their allies into an all-out war against the Arbiter. However, the insurgent forces are driven back as the UNSC's newest and most powerful warship, {{UNSCShip|Infinity}}, arrives in the aid of the Arbiter. All the while this is taking place, [[Jul 'Mdama]], a member of the Abiding Truth imprisoned on Trevelyan, looks for a way to escape his confinement and soon learns of the [[Ur-Didact|Didact]], a mighty Forerunner commander who once held a hatred for humanity. Seeking to enlist the Didact's aid in his crusade against humanity, Jul manages to escape the shield world to the Sangheili colony of [[Hesduros]], where the locals agree to join forces with him in his search for the Didact, laying the foundations for a [[Jul 'Mdama's Covenant|powerful new Covenant group]].

In the following years, a number of [[Covenant remnants|remnant factions]] of the former Covenant continue to spring up, with numerous independent warlords laying claim to the Covenant's legacy in spite of the Arbiter's efforts of building peace between the fragmented Covenant and the UNSC. In response to these splinter groups as well as the budding resurgence of the colonial insurrection, the UNSC creates a new generation of [[Human augmentation|augmented]] supersoldiers in the [[SPARTAN-IV program]]; these events are detailed in the comic series ''[[Halo: Initiation]]'' and the novelette ''[[Halo: New Blood]]''. In the game ''[[Halo: Spartan Assault]]'', players take control of SPARTAN-IV supersoldiers in [[Battle of Draetheus V|a battle]] against a [[Merg Vol's Covenant|rogue Covenant faction]]; one of many [[Post-Covenant War conflicts|disparate conflicts]] in the years following the Human-Covenant War.
{{Clear}}

====Requiem and the Didact====
{{Main|Halo 4|Battle of Requiem|Raid on Ivanoff Station|New Phoenix Incident|Halo: Spartan Strike|Battle of Installation 03|Battle of New Phoenix}}
[[File:Halo 4 standard edition (ESRB).png|thumb|150px|''Halo 4'' centers around the return of the Master Chief and the threat of the Didact.]]

Aboard the severed aft half of the {{UNSCShip|Forward Unto Dawn}}, drifting through space for over four years, [[Cortana]] notices that the ship's intruder alarms have activated and wakes [[John-117]] from [[Cryo chamber|cryo-sleep]]. Fighting their way through boarding parties of [[Jul 'Mdama's Covenant]], the duo discover that the ship is orbiting a Forerunner world. Suddenly, a gaping maw on the face of the planet opens and forcibly pulls the ''Dawn'' and several Jul's Covenant ships inside.

Having crash-landed on the shield world, which they soon learn is known as [[Requiem]], John-117 and Cortana engage the occupying Covenant forces while attempting to find a way back to UNSC-controlled space. Meanwhile, {{UNSCShip|Infinity}} is approaching Requiem, oblivious of the artificial [[gravity well]] which pulled the ''Dawn'' inside. While attempting to find a way to contact ''Infinity'', John-117 and Cortana are attacked by mechanical [[Promethean]] forces. Activating a supposed broadcast relay in Requiem's core, John-117 instead accidentally releases a Forerunner commander known as the [[Ur-Didact|Didact]] from imprisonment. The Didact declares the return of the Forerunners as the galaxy's rulers and saviors. Having always revered the Forerunners as gods, Jul's Covenant quickly swear alliance to the Promethean.

Escaping the core of Requiem, the Chief and Cortana arrive just in time to witness the UNSC ''Infinity'' crashing on the surface of Requiem. The Didact makes for the crash-site, followed by the Master Chief, who reunites with the UNSC and ''Infinity''{{'}}s executive officer, [[Commander]] [[Thomas Lasky]], for the first time in years and assists in the defense of the stranded ''Infinity'', and with the help of Marines and [[SPARTAN-IV program|SPARTAN-IVs]], eventually driving back the Didact and the Covenant forces. Afterwards, [[Captain (Navy)|Captain]] [[Andrew Del Rio]] has a difference of opinion with the Master Chief on whether or not they should leave Requiem, or stay and deal with the Didact. During a mission, the Master Chief encounters a vision from the [[Librarian]], who warns him of the Didact's plan to enslave humanity using a device known as the [[Composer]]. Despite this, Captain Del Rio orders the ''Infinity'' to leave Requiem immediately. Disobeying orders, the Master Chief stays behind in an effort to stop the Didact.

John-117 pursues the Promethean and his Covenant remnant allies to ''[[Ivanoff Station]]'', where the Didact plans to acquire the Composer. Despite the efforts of the Master Chief, the Didact eventually uses the Composer to [[Mind transfer|digitize]] the occupants of ''Ivanoff'', save for John-117 who is saved by the Librarian's enhancements. The Didact subsequently plans to use the Composer to attack Earth; the Master Chief follows him in close pursuit aboard a [[F-41 Broadsword|Broadsword]] space fighter. When the Didact reaches Earth, the ''Infinity'' and [[Battlegroup Dakota]] engage [[Mantle's Approach|his ship]] immediately. Armed with a [[HAVOK tactical nuclear weapon|HAVOK nuke]], John-117 makes his way into the ship and confronts the Didact, but not before the Promethean general uses the Composer to digitize the population of [[New Phoenix]], [[United Republic of North America|URNA]]. With the Chief incapacitated by the Didact, Cortana, nearing the end of her life, immobilizes the Didact with [[hard light]] bindings. With the last of his strength, John disables the Didact with a [[Z-040 Attenuation Field Generator/Localized|pulse grenade]], sending him falling to a slipspace rupture beneath the Composer, and detonates the nuclear bomb manually. Using the last of her power, Cortana saves the Master Chief from the blast and the two meet for one last time before Cortana fades away. Left floating in the debris field, John-117 is recovered and taken aboard the ''Infinity''.

=====The Next 72 Hours=====
{{Main|Halo: Escalation Issue 8|Halo: Escalation Issue 9|Halo: Escalation Issue 10|Mission to Installation 03}}
[[File:HaloEscalation10.jpg|thumb|150px|''The Next 72 Hours'' takes place shortly after the events of ''Halo 4''.]]
In ''The Next 72 Hours'', an arc of the comic series ''[[Halo: Escalation]]'', it is revealed that the Didact survived his defeat aboard ''Mantle's Approach''. After falling through the Composer's slipspace portal, he finds himself on [[Installation 03]] and encounters the [[monitor]] [[859 Static Carillon]]. John-117, reunited with his SPARTAN-II compatriots of [[Blue Team]] — [[Linda-058]], [[Kelly-087]] and [[Frederic-104]] — after several years, confronts the Didact and with the aid of Static Carillon, defeats the Forerunner commander by subjecting him to the effects of multiple Composers. Static Carillon takes Installation 03 for safekeeping while the Spartans return to Earth. After being debriefed, the Master Chief returns to his team and they depart for new battles — without the knowledge or authorization of [[Terrence Hood|Lord Hood]].

====Return to Requiem====
{{Main|Spartan Ops|Requiem Campaign}}
[[File:Majestic saluting.png|thumb|left|250px|[[Fireteam Majestic]] are the protagonists of the ''[[Spartan Ops#Halo: Infinity|Halo: Infinity]]'' CGI series.]]
While their defeat at Earth proved a set back for the Prometheans and Jul's Covenant, it did not result in their defeat. Months later, in [[2558|February 2558]], the ''Infinity'' returns to Requiem with a complement of Spartans, determined to reclaim the shield world. Once there, ''Infinity'' engages in combat with Jul's Covenant fleet, and deploys ground forces, including Fireteams [[Fireteam Majestic|Majestic]] and [[Fireteam Crimson|Crimson]] as well as detachments of other UNSC military forces on the planet. The Spartan fireteams run through a series of search and destroy, rescue, artifact recovery, extraction and assassination ops.

During one of these operations, a mysterious [[Requiem slipspace artifacts|Forerunner artifact]] is uncovered and subsequently brought aboard ''Infinity''. After the device teleports [[Henry Glassman|Chief Engineer Glassman]] to the surface of the planet, [[Catherine Halsey|Dr. Catherine Halsey]] is brought in to investigate. Glassman is taken captive by the [[Jul 'Mdama's Covenant]] and is ordered to activate the [[Librarian]]'s shrine, though he is not successful. Dr. Halsey begins dialog with an unknown party who shares her interest in the Librarian. The intelligence is actually [[Jul 'Mdama]], who is manipulating Halsey into divulging vital secrets about the Forerunners. Halsey is apprehended after her unwitting communication with 'Mdama is discovered. Meanwhile, [[Gabriel Thorne|Spartan Thorne]] rescues Dr. Glassman and the pair escape custody.

[[File:HaloEscalation23.jpg|thumb|150px|''The Absolute Record'' takes place between ''Spartan Ops'' and ''Halo 5: Guardians''.]]
After Dr. Halsey briefly escapes imprisonment and resumes her communication with 'Mdama, ''Infinity'' is boarded by Covenant and [[Promethean]] forces who capture Dr. Halsey. They take her to the Librarian's "shrine", where 'Mdama awaits. Captain Lasky consults with [[Admiral]] [[Serin Osman]], head of the [[Office of Naval Intelligence]], who orders Lasky to assassinate Dr. Halsey. Against Lasky's protests, Commander Palmer departs to execute the order. However, Lasky sends Fireteam Majestic to rescue Dr. Halsey and stop Palmer. Meanwhile, Dr. Halsey successfully activates and enters the Librarian's shrine. The Librarian's essence gives Dr. Halsey an artifact known as the [[Janus Key]], but Jul 'Mdama gets one half of the key. Halsey tosses Gabriel Thorne the other half before she is abducted by 'Mdama.

Believing to have obtained what they were looking for, Jul 'Mdama sends Requiem to be destroyed by a [[Epoloch|nearby star]]. Deactivating a slipspace anchor originating from Requiem, the UNSC ''Infinity'' narrowly escapes the planet's [[Gravity well (physics)|gravity well]]. Afterwards, Lasky and Palmer observe as Dr. Glassman studies one half of the divided Janus Key. Meanwhile, aboard a Covenant ship, Dr. Halsey seemingly agrees to collaborate with Jul 'Mdama and his forces.

====Absolute Record====
{{Main|Halo: Escalation|Battle of Aktis IV|Operation: ATHENA}}
The comic series ''[[Halo: Escalation]]'' picks up where the events of ''Spartan Ops'' left off, continuing the story of the ''Infinity'' crew and further exploring the galactic status quo. After several missions unrelated to the preceding events, ''Infinity'' is lured into a trap by Jul 'Mdama and Dr. Halsey, resulting in [[Battle of Aktis IV|a battle]] over the Janus Key. 'Mdama and Halsey eventually gain both halves of the artifact, revealing them the location of a critical Forerunner site known as the [[Absolute Record]]. 'Mdama's Covenant and Halsey eventually reach the Record, trailed by a UNSC strike team. Due to interference from the Forerunner site's [[Invariant Bias|Custodian]], neither side manages to unlock the facility, while the AI confiscates the Janus Key. Both sides flee the Record, with 'Mdama's Covenant forces suffering heavy losses and [[Sali 'Nyon's Covenant|fracturing]].
{{Clear}}
====The Created====
{{Main|Hunt the Truth|Halo 5: Guardians|Battle of Sunaion|Battle of Genesis}}
[[File:H5 final cover art.png|thumb|150px|''Halo 5: Guardians'' centers around Fireteam Osiris and Blue Team and the threat of Cortana.]]
[[John-117|Master Chief]] and [[Blue Team]] go absent without leave to pursue the AI construct and Chief's former companion [[Cortana]]. With Blue Team's loyalties called into question, Spartan [[Jameson Locke]] and [[Fireteam Osiris]] are sent to locate and return them to the [[United Nations Space Command]]. 

Blue Team go to the ONI station [[Argent Moon]] and destroy it, but not before John-117 has a vision of Cortana. Blue Team flees the Argent Moon in a [[Winter-class prowler]] and head for [[Meridian]]. Fireteam Osiris is told about Blue Team going to Meridian, and they follow. Osiris helps the colony before they eventually set out to find Blue Team. Osiris then encounters the [[Warden Eternal]] and they fight.

After Fireteam Osiris defeats the Warden they follow Blue Team's footsteps and come across a [[Guardian Custode|Guardian]]. Locke and John fight, and eventually the Guardian leaves with Blue Team aboard, while destroying most of Meridian. 

Osiris then joins [[Thel 'Vadam]]'s forces on Sangheilios, to find another Guardian that has been resting under [[Sunaion]]. After defeating many Covenant forces, and even a Kraken, the Arbiter and Osiris head to Sunaion. The Arbiter defeats the Jul's Covenant, and Osiris boards the Guardian, with [[Sarah Palmer]]'s help. 

While Fireteam Osiris is fighting Covenant forces alongside the Arbiter, Blue Team arrives on [[Genesis]]. While Blue Team fights Covenant forces that have arrived through the slipspace portal that the Sunaion Guardian left, Cortana leads them towards a [[Forerunner]] building. The [[Gateway]] to the [[Domain]]. Blue Team encounters the Warden Eternal, and after a bit of talking they fight. Cortana then leads Blue Team into the Gateway

Fireteam Osiris arrives at Genesis in the Sunaion Guardian, and they look for Blue Team. They meet [[031 Exuberant Witness]] and she helps Osiris by bringing in a [[M820 Scorpion]]. Osiris takes the Scorpion and fights through the remnants of Jul's Covenant and Prometheans, who were already fighting each other. Osiris then reaches the Gateway and battles two Warden Eternals in a courtyard. Once the Wardens are defeated Osiris follows Blue Team. Right when Osiris reaches them Cortana transports Blue Team inside the Gateway, and Osiris are left to find them.

Inside the Gateway the Warden tries to stop Blue Team from reaching Cortana, despite her best attempts to stop him. They fight through many Prometheans, and eventually the Warden Eternal tries to stop them with three of his bodies. Blue Team defeats all three of his bodies and move on. In the next area the Warden brings in multiple bodies, too many for Blue Team to fight. Blue Team is backed onto the edge of a platform, and before the Warden can kill them, Cortana dissolves his bodies. Blue Team confronts Cortana, and she announces her plans to seal Blue Team in a [[Cryptum]]. They are unable to do anything, and Cortana seals them in.

Exuberant and Osiris must stop Cortana from locking Blue Team away for thousands of years. While Osiris fights Prometheans, multiple UNSC [[Artificial intelligence]]s begin to swear their allegiance to Cortana, beginning the [[Created]]. Osiris fights in a large area and destroys a number of generators. After that they enter another building and defeat the last of the Prometheans in their area. Locke destroys another generator and Blue Team's Cryptum is brought back to them. Cortana leaves with part of her plan being foiled. She arrives over [[Earth]] with one of her Guardians and uses the Guardian's [[EMP]] to shut down most of the planet's power and defenses. While this happens the [[UNSC Infinity|Infinity]] flees Earth's orbit.

====The Banished and the Ark====
{{Main|Halo Wars 2|Second Ark Conflict}}
After 28 years adrift the crew of the {{UNSCShip|Spirit of Fire}} find themselves at Installation 00 under the control of the Jiralhanae [[Atriox]]'s [[Banished]].

The Spirit of Fire's crew is suddenly woken up by the ship's former [[Artificial intelligence]] [[Serina]]. 
{{Clear}}
{{Expand-section}}

==Non-canon alternate universes==
===Silver Timeline===
{{Main|Silver Timeline}}
An alternate continuity created for ''[[Halo: The Television Series]]''.{{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=26|M=1|Y=2022}}
===Fractures===
{{Main|Fractures}}
Several fantastical alternate universes with unique twists on the main ''Halo'' universe.{{Ref/Site|Id=CF118|URL=https://www.halowaypoint.com/en-us/news/myths-mysteries|Site=Halo Waypoint|Page=Canon Fodder 118 - Myths & Mysteries|D=2|M=9|Y=2021}}
==In our universe==
[[File:Xbox-360-halo-reach-edition.jpg|thumb|150px|The ''Halo: Reach'' Xbox 360 S.]]
The first Halo title ''Halo: Combat Evolved'' quickly became known as the first "Killer App"<ref>''Electronic Gaming Monthly'' issue 150</ref> for Microsoft's popular [[Xbox]] video game console when it was released on November 15, [[2001]], achieving both critical acclaim and financial success. ''Halo'' was later published on the PC and finally released for the Mac (for which it was originally developed prior to Microsoft's acquisition of developer Bungie). Shortly after that, the company (Gearbox Software) that ported Halo to PC released ''[[Halo Custom Edition|Halo: Custom Edition]]'' as a free, downloadable and achievable extension to the Windows port of Halo.

The second game, ''Halo 2'' was released on November 9, [[2004 (real world)|2004]], for the Xbox breaking sales records and becoming the fastest selling United States media product in history. ''Halo 2'' US sales top 125 million dollars.

A third game, ''Halo 3'', was released on September 25, [[2007 (real world)|2007]], for the [[Xbox 360]] and closes this chapter in the Halo series. The ''Halo'' games have become well known for the high quality of their graphics, gameplay, physics, and storyline. ''Halo Wars'', a Real Time Strategy game, was released for the Xbox 360 on March 3, [[2009]]. ''Halo 3: ODST'', another First-Person Shooter, was released on the Xbox 360 on September 22, 2009. The next game in the franchise, ''[[Halo: Reach]]'', was released on September 14, [[2010]] for the Xbox 360. As a gift to the original players of ''Halo: Combat Evolved'', and also to those who never had the chance to play it, an [[Halo: Combat Evolved Anniversary|Anniversary Edition]] was released for the Xbox 360 on November 15, [[2011]], with revamped graphics and extra features. 

The [[Reclaimer Saga]] was the second generation of the Halo video game franchise.  The series launched with ''Halo 4''<nowiki>'s</nowiki> release on November 6, [[2012]]. ''Halo: Spartan Assault'', a top-down shooter, was released on July 18, [[2013]] for Windows 8 and later for the [[Xbox One]], Xbox 360, and Steam. ''[[Halo: The Master Chief Collection]]'', a collection of ''Halo'' games including ''Halo: Combat Evolved Anniversary'' and ''Halo: Combat Evolved''<nowiki>'s</nowiki> multiplayer, ''[[Halo 2: Anniversary]]'' and ''Halo 2''<nowiki>'s</nowiki> multiplayer, ''Halo 3'', ''Halo 3: ODST''<nowiki>'s</nowiki> campaign, and ''Halo 4'', was released for the Xbox One on November 11, [[2014]] and later on PC. ''Halo: Spartan Strike'', a spiritual sequel to ''Halo: Spartan Assault'', was released on April 16, [[2015]], for Windows 8. The second game of the Reclaimer Saga, ''[[Halo 5: Guardians]]'', was released on October 27, 2015, for the Xbox One.

''Halo Wars 2'' was released on February 21, [[2017]] for Xbox One and PC. ''Halo: Fireteam Raven'', an arcade game, was released on July 10, [[2018]]. 

''Halo Infinite'' was released on December 8, [[2021 (real world)|2021]] for Xbox One, Xbox Series X/S, and PC. It marked the start of a "spiritual reboot", transitioning from the Reclaimer Saga to the series third generation of mainline campaigns.

Further expanding the ''Halo'' universe are [[Halo novels|several novels]], which provide insight into the background story.

==Gallery==
<gallery>
File:1206904788 Halo-Ring.JPG|The titular Halo. 
File:Halo-Logo.png|The official ''Halo'' logo, 1999-2010.
File:Halo logo.png|The ''Halo'' logo for ''[[Halo: Reach]]'' and related media.
File:Halo logo (2010-present).png|The ''Halo'' logo 2010–present.
File:Halo Generations by Halcylon.jpg|The progression of the original Halo trilogy.
File:Bungie Haloverse.jpg|An image covering the Halo Universe as developed by [[Bungie Studios]].
File:Old_Waypoint_Halo_101.png|A quick brief of the then ''Halo'' Universe as shown on ''Halo Waypoint'' in [[2009]].
File:Halo 15thanniv banner.png|''Halo''{{'}}s 15th anniversary banner.
File:Halo 15thanniv bannerfull.jpg|''Halo''{{'}}s 15th anniversary banner without logos.
File:Halo 20 Year Celebration ArtworkClean.jpg|''Halo''{{'}}s 20th anniversary artwork without logos.
</gallery>

==References==
{{Reflist}}

==Sources==
{{Ref/Sources}}

==External links==
*[http://www.halowaypoint.com/en-us Halo Official Site]

[[Category:Universe and lore]]