Many of the alien species conquered by the Covenant are conscripted into, or gradually become part of the alliance. However, during the first contact with the humans, the Oracle on board the Forerunner dreadnought revealed to Truth and Regret that Humans are Reclaimers, as shown by its luminary. Since the entire Covenant was based on the belief that the Forerunners had transcended, Truth and Regret knew if any of the other races found out what the Oracle told them, the Covenant would cease to exist.
The highest caste, the San'Shyuum, or "Prophets" as Humans call them, lead the Covenant and exert complete control over all religious and political affairs. Though physically weak, Prophets wield power through absolute command of the Covenant and through scavenged Forerunner technology, leaving the task of conquest to the Sangheili and the other races. Their higher understanding of the Forerunners gives them great ego and religious influence over the Covenant. The High Prophets are addressed as "Hierarchs," "Noble Hierarchs," "Holy Ones," or "Exalted" by the other races of the Covenant.
The second highest caste; Sangheili, or Elites as Humans call them, served as the military leaders of the Covenant before the Great Schism in 2552. While Prophets often had the final say, it was the Sangheili who organized military campaigns and naval engagements. They maintain the military structure of the Covenant and ensured the Prophets' orders are followed, as well as their own. Sangheili consider the other client races to be below them in all ways. The Sangheili are the only known race permitted to build and operate starships within the Covenant, though the crews are almost always composed of a mix of races. Sangheili are separated into ranks based on skill and experience. To advance in rank, Sangheili must honorably earn such advancements on the battlefield. They were a major component of the Covenant and were the only caste able to maintain the military hierarchy as well as having a voice within the High Council before the Great Schism. An "ee" at the end of a Sangheili name, such as "'Zamamee or 'Vadumee," signifies that that Sangheili is a part or was part of the Covenant military, although, after the Great Schism most, if not all, Sangheili removed the "ee" from their names to show that they had left the Covenant.
Jiralhanae, known to Humans as Brutes, They are one of the newer species to the Covenant and are the only race that has obtained very close to equal status to that of one of the founding "clients" of the Covenant pact, the Sangheili. They have an incredible natural resilience to damage due to their tough hides, which easily make up for their lack of energy shields, and use a number of weapons and vehicles based upon their pre-Covenant technology. This technology, though primitive compared to other Covenant weapons, is nonetheless extremely lethal, with most Jiralhanae-developed weapons having blades attached to them. In addition to their standard form of combat, Jiralhanae will sometimes go "berserk" and try to kill anyone or anything in their path. This shows the aggressive nature of the Jiralhanae, and the little tolerance they have when they are cornered. Jiralhanae have their own ranks going up to War Chieftains who usually wield plasma cannons, fuel rod guns, or Chieftains who usually wield gravity hammers. The Jiralhanae always work in packs of 3-8 when possible. They took over the role as personal bodyguards of the Prophets and also now make up most of the Covenant military.
Huragok, or Engineers, are actually an artificial species created by the Forerunners. They will only converse with the Prophets or individuals who learn their language. This indicates Engineers are very high in the caste system, however ONI believe them to be prisoners or slaves. The Huragok perform the physical labor of excavating, and gathering data on Forerunner artifacts. In military terms, they are generally a non-militant race. However, at times in the Human-Covenant war they have been placed on the battlefield either as repair workers or suicide bombers. They have also displayed neutrality and even some allegiance to humans such as Lighter Than Some helping the citizens of Harvest escape and another Engineer repairing Ascendant Justice's engines for John-117 and even a Needler for him to use in battle. Another example is one Huragok repairing and recovering the Human AI Superintendent and then assisting Captain Veronica Dare and Sergeant Major Avery Johnson in working out what the High Prophet of Truth was looking for in Africa. It was also revealed that they are equipped with a personal energy shield only when they are under duress. Additionally, these Huragok are also able to project an energy shield around its allies, or enhance shielding already present, if they are within its proximity.
Mgalekgolo, or Hunters as they are known by Humans, are thought to be giant monsters, but they are actually an assemblage of worm-like entities called "Lekgolo" that creates a large, armor plated form. In this form, they are known as "Mgalekgolo." They always fight and travel in pairs known as "Bond Brothers" which technically means that not all of the colonies of worms were able to fit within one set of armor, and are the strongest of the Covenant fighting units. They wield powerful assault cannons and a massive shield resistant to any small arms fire which may also be used as a melee weapon due to its sharp sides and the Mgalekgolo's great strength. They are usually used as weapons platforms, and are only deployed on the battlefield when in need of a heavy force - they are used more like heavy duty equipment than soldiers. Their political and religious motivations are completely unknown.
These flying insect-like creatures, also known as Drones or Buggers by Humans, served almost exclusively as engineers, but were then replaced by the Huragok. This created a hatred towards the new, peaceful engineers by the Yanme'e that sometimes resulted in violence. Afterwards, the Yanme'e were used as aerial combatants against the UNSC, who were inexperienced at fighting airborne infantry. In combat, their weapons of choice were the Needler, which creates a super-combine explosion if enough projectiles are fired into the same target, and the Plasma Pistol. Their ability to fight on the wing, and their usual deployment in large groups, made them an excellent strategic weapon against ground-based opponents.
Due to their superior senses, the Kig-Yar, or Jackals/Skirmishers as they are known by Humans, are the scouts and marksmen of the Covenant military, they are the second lowest Covenant caste. Due to their lack of physical durability, they carry a portable energy shield generator during combat. Kig-Yar are employed mainly as sharpshooters with their excellent vision and dexterity, and are also deployed to defend strategic areas. When a Kig-Yar is under fire, it will cover its head with its hands and trot away to another position from which to fire. The first Human contact with the Covenant was between Staff Sergeants Johnson and Byrne on a Human freighter as Kig-Yar pirates tried to board the ship. The Kig-Yar have very strong dislike of the Unggoy because they are always trying to assert their superiority over them in the caste system of the Covenant. Once they poisoned a recreational narcotic that the Unggoy use which nearly caused them to become infertile. This caused the Unggoy Rebellion.
Hailing from Balaho, Unggoy, known as Grunts among Humans, are the most common and lowest-placed caste of the Covenant. The Unggoy were barely into their own Iron Age when the San'Shyuum discovered them. Classified as a "Tier 6" civilization by the Forerunner charts, the Unggoy were at a primitive point in their cultural development, the Unggoy had little choice but to accept entry into the Covenant hegemony, or otherwise risk extinction. After their incorporation into the Covenant their entire history was erased and they essentially became a slave race. Despite their notable cowardice and ineptitude, they are quite dangerous in large numbers, which was why an Arbiter was needed to quell the Unggoy Rebellion. They breathe methane and thus must wear a large tank on their back full of the methane to survive on other planets. Relations between the Unggoy and the Kig-Yar are strained in the best of times.
Earth (known as Erde-Tyrene by prehistoric humans and Forerunners) is the third planet of the Sol system, and one of its four terrestrial worlds. Homeworld of the human species, Earth has been at the forefront of galactic history, from encounters with the Precursors to the end of the Covenant Empire. Inhabited long ago by a prehistoric interstellar human government conquered and dissolved by the Forerunners, Earth is currently the capital world of the Unified Earth Government.
Earth was possibly the most populated planet of the human space territories. For a significant amount of humanity's history, it was their only known place in the universe to support life.
The Earth first formed about 4.6 billion years ago, and gave rise to the first single-celled organisms about 3.9 billion years ago. About 200,000 years ago, the ancestors of modern humans, Homo Sapiens, evolved in Africa. Indigenous to Eastern Africa, they gradually spread across the entire planet. Eventually, the humans, originally consisting of groups of hunter-gatherers, began to develop into civilizations.
Human civilizations gradually became more and more complex, and eventually, possibly through contact with the Forerunners, humanity discovered spaceflight and spread across the Orion Arm of the Milky Way galaxy. After being defeated in a war against the Forerunner civilization, the humans were exiled back to Earth, with their species devolved and splintered into multiple subspecies and their culture degrading back to a primitive state for millennia.
After the war with the Forerunners, Earth and humanity came under the charge of the The Librarian, a Forerunner Lifeshaper who helped the humans slowly work towards rebuilding a primitive civilization. Remnants of their former technology, such as steam power and hot-air balloon flight, were re-learned under her care but later forgotten after the firing of the Halo Array.
Near the end of their war with the Flood, the Forerunners built a machine to generate a slipspace portal to the Ark in Africa. They also indexed the human species as a part of their Conservation Measure to preserve life in the galaxy after the activation of the Halo Array. After the array's activation, human life was planted back on Earth, where it successfully re-developed.
Civilization and the Modern Age
After the recovery from the Array, humans reduced back to hunter-gatherers for nearly a hundred thousand years, until civilizations began to form anew.
By the year 1914, much of the world was divided into two factions, the Triple Entente, or Allies: the United Kingdom, France, Russia, and later the United States of America, and the Triple Alliance, or Central Powers: Germany, Austria-Hungary, and other nations of similar ideals.
The Central Powers were defeated at the end of World War I in 1918, resulting in a decade of prosperity for the Allies, followed by an economic depression and the rise of Fascism, Nazism, and Communism in many countries. In 1939, another World War erupted, between the Allies (Britain, the Soviet Union, which were, again, later joined by the United States, and many other nations) and the Axis (Nazi Germany, Fascist Italy, and the Empire of Japan). In 1945, the Allies defeated the Axis. Later that year, the victorious nations, in an attempt to prevent more World Wars, founded the United Nations, an international assembly of peaceful nations, whose goal was to settle international disputes peacefully, and was the predecessor to the UNSC. In 1957, humanity finally made their way into space with unmanned probes and by 1961, humans themselves had gone into space. In 1969, humanity had finally stepped on an extraterrestrial surface-Earth's Moon.
After World War II, humanity would lack war on that scale, although smaller wars and conflicts erupted, including the Korean War, Vietnam War, Cold War, and the first and second Iraq War. In the early 21st century, terrorism became a particular thorn in the side for the nations on Earth and small wars broke out along with civil unrest in many countries. However, no full wars on the same scale as past World Wars erupted until two centuries later.
Interplanetary colonization and conflicts
By 2080, humanity's national governments, under the auspices of the United Nations, had begun to establish colonies on the other planets in the Sol system. However, expansion did not come without problems. In the mid-22nd century, two major dissident factions emerged; the neo-communist Koslovics and fascist Frieden, which began to battle one another and the United Nations.
In March–June 2160, Jovian Frieden secessionists attacked members of the United Nations on the moon Io, which led to three months of fighting between the Earth military and Jovian Frieden forces. National governments began to support their own colonies which sparked proxy wars off-planet, leading to tension and militarization on Earth. In 2162, armed conflict ripped through South America, starting the Rain Forest Wars, as Koslovic, Frieden, and UN forces all clashed over ideological differences, sparking additional conflicts off-planet. In December of 2163, the three factions clashed, this time on Mars. This was the first extraterrestrial use of Marines, who launched lightning raids on Koslovic positions, permanently affecting military doctrine for centuries. In 2164, UN forces began a massive military build-up and began the first true interplanetary war. The forces of the fledgling United Nations Space Command were significantly bolstered by a massive propaganda campaign running on the victories on Mars and over the next six years took back the Sol system and drove the dissident factions to destruction. Now with a massive military with no enemy to fight, overpopulation, famine, and a collapsing economy, the newly unified Earth faced an uncertain future.
It was not until 2291 that this problem was solved when researchers created the Shaw-Fujikawa Translight Engine which enabled superluminal travel by allowing access to an alternate domain known as Slipstream Space. In 2310, the UNSC unveiled their first line of colony ships and the best and brightest from both civilian walks of life and the military set out to form the Inner colonies. This eased the overpopulation problem upon Earth which became the capital of the Unified Earth Government, while the inner colony of Reach would later become the headquarters of the UNSC.
The Human-Covenant war
All this was suddenly and violently rendered a moot point when a single alien ship made an unprovoked attack on the colony of Harvest, humanity's first encounter with an alien civilization - the Covenant. Over the next twenty-seven years, humanity would wage a brutal war for survival, losing hundreds of colonies, including all of the Outer Colonies in 2536; and on 31 August 2552, the UNSC's largest military installation, the planet Reach, was destroyed by the Covenant. During the entire course of the conflict, the UNSC followed the Cole Protocol, which declared that no UNSC vessel targeted by the Covenant was to retreat to Earth, as a means of ensuring the secrecy and security of the planet's location. In nearly twenty-seven years of galactic warfare, the Covenant never succeeded in determining the location of Earth through the measures taken under the Cole Protocol. However, by September 2552, Earth was humanity's last major stronghold in its war against the Covenant.
Despite the effectiveness of this law, on 20 October 2552, the Covenant launched their first attack upon Earth, rendering the Cole Protocol moot and initiating the final confrontation between UNSC forces and the Covenant.
Pre-Battle of Earth
Prior to the Covenant invasion of Earth, there had been a suppressed influx of information by ONI, resulting in people going about their normal lives even up until the attack. Several fleets were brought to Earth. Some like the Fifth Fleet were merged with the Home Fleet in a special command grouping.Other fleets brought to Earth include the Second Fleet, Seventh Fleet, and the Sixteenth Fleet. The 6th Battle Group along with large amounts of Marines, Army Troopers, and ODSTs present, five SPARTAN-IIs were also brought to or were near Earth.
Following the victory at the Battle of Earth and the Battle of Installation 00, the Human-Covenant war ended in March 2553. Many of Earth's cities were left in ruins and the planet's population was sharply reduced as a result of the Covenant invasion. With the war's end and the departure of the Covenant separatists to their respective homeworlds, the UNSC began to rebuild the extensive damage inflicted upon Earth's infrastructure and human population. Following the end of the Human-Covenant war, Earth saw an influx of refugees from former Covenant species, who were walled off in "conclaves."
On July 25, 2557, Shadow-of-Sundered-Star moved into targeting range in the Mantle's Approach with the Composer and proceeds to compose the residents of New Phoenix. John-117 and with the help of Battlegroup Dakota, flew a Broadsword into the ship. There he confronted the Didact and used a Pulse grenade to send him through a slipspace portal to Installation 03. John then detonates a HAVOK Tactical Nuclear Weapon, destroying the Composer and the ship. This was then dubbed the New Phoenix Incident and the city was placed under quarantine until eight months later on 24 March 2558.
In 2557, only six months after the New Phoenix Incident, an unknown Sangheili refugee attempted to detonate a HAVOK Tactical Nuclear bomb in Rio de Janeiro, but was apprehended by Fireteam Majestic before he could do so.
At the beginning of The Reclamation, the Created knocked out power on Earth and occupied it.
The UNSC Supreme Headquarters is located on Earth and somewhere within the United Republic of North America and is most likely where Earth is governed. This is mostly likely because the United Nations existed in New York City for a long time. It is very possible that the UNSC Supreme Headquarters was falsely identified and it is actually supposed to be the UEG's headquarters or doesn't exist. Not much else is known about Earth's specific government.
Trade was one of the most important parts of the economy of Earth as most planets gathered resources to be sent back to Earth. This can be seen with Harvest, as they exported to Earth; mineral water, livestock and vegetables and fruit goods. As well, colonies like Reach exported out (presumably) metals like Titanium, to Earth. There are six orbital elevators on Earth that can allow for products to move off and on the planet.
Earth was one of the, if not the most heavily defended planets in the human space as it was the capital of the UEG. Sydney contained the HIGHCOM Facility Bravo-6, the UNSC's headquarters, which was nicknamed 'The Hive'.
There were over three hundred operational Orbital Defense Platforms. As well, there was the UNSC Home Fleet that would help defend Earth and any other Sol system colony. Large amounts of Marines, ODSTs, and Army Troopers were as well on Earth or in system.
In the Post-War Era, the Home Fleet had a new formation called Battlegroup Dakota that consisted of the UNSC Infinity plus several newer UNSC Starships.
UN clashes with dissident political movements, the most important of which were the "Koslovics" and the "Frieden," began the crisis that led to the formation of the UNSC. The Frieden movement was a fascist organization based on the Jovian Moons, a group that received backing from some corporations operating in the Federal Republic of Germany on Earth. Their ideological opponents, the Koslovics, formed a Marxist–Leninist group centered around the leadership of Vladimir Koslov around the same time.
The UNSC was commissioned in 2163 as a military force primarily composed of Naval and Marine forces. In July 2164, the UNSC partook in its first battle. From this point, the UNSC was used by the UN in conflicts, including the Interplanetary War.
With the conflicts of Sol over, a newly powerful Unified Earth Government and UNSC began to expand into the stars. At about 2490, the planet of Reach would become extremely important to the UNSC. It would become a major naval yard and training center.
The apex of human expansion would come in 2490, when more than 800 worlds were considered part of the UEG's territory, many developing into full-fledged colonies. By this time, a ring of Outer colonies was providing the UEG with the raw materials that made the macro-economy function; with the political power remaining with the Inner colonies. The massive difference in wealth distribution and political power, which became a hallmark of humanity by this period, led to new threats of secession from the outer ring.
Winds of Insurrection
In 2492, the colony of Far Isle was razed by nuclear weapons after a massive uprising, creating a new found reason to rebel. The Callisto Incident in 2494 would begin a bloody struggle against groups of terrorists (or freedom fighters), who wanted independence. The UNSC battled them for nearly three decades. As the situation deteriorated, the UNSC created the SPARTAN-II Program, which was headed by one Catherine Halsey.
The Human-Covenant War
In 2525 a CMA battlegroup had been decimated. Upon investigation from the only surviving ship, the CMA Heracles it had been discovered that humanity was not alone. The planet the battlegroup was at, Harvest, was completely destroyed. The UNSC was placed on high alert. On November 1st, the UNSC stripped away the Colonial Military Administration and gave its forces to NAVCOM and UNICOM.
Decades of War
The beginning phase of the war was marked by disastrous defeats, and even more costly victories. Aside from the Second Battle of Harvest in 2526, where a large force led by Vice Admiral Preston Cole barely defeated a smaller Covenant fleet, the UNSC's influence on their territories quickly dwindled in the course of their struggle. In the span of a few years, the Covenant had managed to capture and destroy the majority, if not all of the Outer Colonies, and a small portion of the Inner colonies.
The Final Year
By 2552, the UNSC, though heavily outnumbered and outgunned, had nonetheless slowed the Covenant's inexorable progress through human space. However, the overall situation remained dire. In desperation, HIGHCOM ordered a high-risk operation. Spartan-II super soldiers were to insert into Covenant space, with a captured Covenant vessel, capture a high-ranking Prophet, and return to UNSC space in an attempt to ransom their own leader for a truce. Before the operation began, the Covenant found and destroyed the fortress world Reach, killing a large portion of the UNSCDF, and rendering most of the Spartans that were to execute the mission KIA or MIA. The Covenant endured heavy losses, both in space and on the planet's surface. However, the largest and most important military world protecting the Sol system had fallen silent. Little hope of continued, successful resistance remained.
On March 3, 2553, the Human-Covenant war officially ended in victory for the UNSC and the Covenant Separatists, but at a staggering price. An estimated twenty-three billion human civilians and military personnel were killed between 2525 and 2553. Most of the UNSC's major military outposts were destroyed, with the exception of Earth which sustained heavy damage. With the defeat of the Covenant though, the UNSC now had a second chance to rebuild, and thrive.
Following the inauguration of Dr. Ruth Charet in January 2553, the UNSC handed back its emergency powers to the UEG on January 8 of that year. The UNSC also maintained its earlier truce with the members of the Covenant Separatists initiated by Lord Hood and the Arbiter. Nevertheless, a black-ops team from the Office of Naval Intelligence that had been supplying arms to a Sangheili faction, one ideologically opposed to the Arbiter, to destabilize their government rendering them incapable of threatening Earth.
The end of the war also returned brought colonial politics back into focus. Many colonies sought to work with the UNSC to help safeguard their homes. However, a number of worlds turned openly hostile to the UNSC and seeking to distance themselves from the UNSC and UEG. Despite this, the UNSC didn't actively respond to most of this. Only if these worlds attempted to violently secede did the UNSC get involved.
As of 2558 Jul 'Mdama's Covenant was actively opposed against the UNSC. The threat would be finally be contained after Jul 'Mdama's assassination at Kamchatka and a final battle at Sunaion. Though this would be overshadowed by the sudden onslaught of the Created, near the end of the year.
Humanity advanced early in its history. Its technology became highly sophisticated, and it outward expanded along the Orion Arm to escape Forerunner control thousands of years before the activation of the Halo Array. Humanity once formed an alliance with the San'Shyuum and later warred against the nascent Flood. Humanity drove the Flood from the galaxy for the next several millennia, but the conflict caused a war with the Forerunners. The Forerunners won and, as punishment by the Didact (Forerunner leader) reduced humanity to a pre-technological state: he stripped them of their technology, smashed their civilizations, and exiled their remnants to Earth. Though The Librarian watched over and guarded humanity as the race scraped itself back together, The Didact used the Composer to destroy a small portion of mankind. Because of this The Librarian locked The Didact away for the safety of humanity and himself.
The development of human civilization as modern humans know it began ten thousand years ago with the Neolithic Revolution, during which humans learned how to systematically use plants to produce edible food-energy. The stability thereby gained enabled more permanent settlements and the development of ever more complex tools.
Innovative toolmaking and the domestication of other species provided human populations greater and greater power to expand their populations, and trade ensured the diffusion of new technologies to adjacent groups. These exploding populations formed the first genuine civilizations over 8,500 years ago in Northern Africa, Southwest Asia, Asia Minor, and elsewhere soon after. The infrastructure of civilizations continued to grow in size and complexity as innovative technologies and larger populations increased food-energy availability. Economic, political, and scientific advancement continued to quicken by automating many tasks in the Industrial Revolution. Human civilization rapidly developed during the 18th through 20th centuries, which comprised an era known as the "Industrial Revolution." The major political and economic ramifications of the rise constitutional governments and refined capitalist resource management techniques enabled such important inventions as automobiles, electrical appliances, and aircraft to enter use at unprecedented scales. Humanity's understanding of medicine and chemistry raced ahead and created anesthesia, along with plastics that could cheaply fulfill an enormous amount of material roles (with the better preservation of food being one of its greatest functions). The average human lifespan of approximately forty-five years leapt to eighty or one hundred years because of antibiotics and other medicines combined with better food production and preservation: the age-old scourges of plague and famine were nearly eradicated.
Mankind more efficiently applied previous sciences and arts, and the art of the military would prove no exception to this pattern. Armed conflicts rapidly changed from the primitive, melee-oriented wars of the past: after two massive wars within the first 50 years of the 20th century, humans invented superior firearms, automatic weapons, radar, tanks, missiles, jet engines, and ultimately the atomic bomb, which became the most powerful weapon then known and later a key component of human arsenals during the brutal war against the Covenant.
Over the next 60 years the superpower nations of the United States of America and the Union of Soviet Socialist Republics (succeeded by the Commonwealth of Independent States) competed in a period of military and cultural tension known as the "Cold War." The lethality of humanity's relatively new warfare technologies, tactics, and battlefield doctrines became more destructive and precise as each nation tried to intimidate the other. In the 1950s, the Soviet Union launched the earliest satellite and sent the first human, Yuri Gagarin, into space, officially making humans space faring (and thus at Tier 5 in the Technological Achievement Tiers). The United States successfully placed the first human, Neil Armstrong, on the Moon, and eventually surpassed the Soviet Union's space faring and military production capabilities; their doctrines would heavily influence the UNSC in later centuries.
These advancements caused the Digital Revolution, in which computing machines enabled scientific discovery and technological development to accelerate with explosive speed. As larger urban centers and tools for civilian and military uses, along with more modern economic and political systems, developed, individuals enjoyed longer, more pro-creative, and more comfortable lives, now virtually impervious to the creatures from whose midst they sprang. Thus-unchecked, the human population eventually exceeded the carrying capacity of earth by several billion and ultimately created a great need for humans to expand off world.
Additionally, the creation of the Internet in the late 20th century revolutionized communication and data processing, thereby further accelerating mankind's rate of technological progress. World politics also changed with the formation of the United Nations. The religiously neutral nature of many of these constitutional style governments, along with scientific and logical explanations for phenomena and methodology, relatively diminished the weight of ideological dogma. Religion would remain a staple of human societies insofar as advocating personal ethical codes, though unlike that of the Covenant, it was no longer primarily a mere framework to justify a large, hierarchical system of differing castes and birthrights. In the late 20th century, satellites used solar energy instead of primitive battery sources and could therefore work long enough to send and retrieve data and communications and be a method of civilian and military navigation. Although much of the technology used during this time is disregarded as "primitive" by the standards of the 26th century, they were all somehow a precursor to all of technologies utilized later by the UNSC.
The species was able to explore the space immediately surrounding their home planet in the 20th century, as the population began to advance beyond the capacity of the planet to comfortably sustain their civilization. The subsequent conflict over resources, economics, religion and politics on Earth gave way to numerous wars. Furthermore, these tensions put great pressure on the species in the beginning of the twenty-third century, and the transnational organization that became the Unified Earth Government (UEG) engaged in more frequent space colonization and sought to represent the entire species, even though no one state ever previously ruled the entire human race. The development of Slipspace travel in 2291 helped the UEG engage in spreading the human race beyond their home solar system, relieving the serious ecological pressure on the home world.
Simultaneously, this expansion was also to usher in promising new opportunities for humanity, as some of these colonies, such as planet Reach with its bountiful titanium deposits, could offer abundant stores of raw materials that had otherwise been considerably unique and scarce on Earth. With the initial advent of interplanetary trade driving down the costs of what had once been an expensive implementation of their technology - such as the forging of space-worthy ships and naval vessels - the effects from these carefully implemented first colonization projects helped to ensure that interstellar trade, travel and communication were to be more commonplace amongst the general populace in the ensuring centuries, eventually granting humanity the capacity to expand to hundreds of worlds and establish colonies at enhanced rates.
The Great War
The species as a whole was finally pushed into major conflict when, after several centuries of spreading throughout many star systems and inhabiting hundreds of worlds, they discovered the violent, genocidal, theocratic Covenant. As the decades-long war wore on, the human race gained the controversial reputation as a worthy adversary against the Covenant, despite the fact that they were technologically, numerically and physically inferior. Humans with the help of the SPARTANs, could hold out in ground combat and sometimes defeated the Covenant (on the rare occasion, without the aid of the SPARTANs), but in space the Covenant had virtually undisputed supremacy, thanks to their talents for re-purposing Forerunner technology, space tactics and not to mention whenever they were defeated on the ground, they would glass the planet.
Humans have been able to show great bravery when facing insurmountable odds. Some of the members of the Covenant wonder why the Hierarchs had refused to allow the humans to join them, as they had with the crucial contributions of the SPARTAN-IIs been able to hold steadfast even when outmatched in almost every way. However, despite great courage, the future seemed dark for the survival of the human race as the Covenant continued to wipe out their colonies, marching ever closer to Earth. On October 20, 2552, Earth was found. In the ensuing battles over possession of Earth, humanity suffered heavy casualties.
March 3, 2553, saw the end of the Human-Covenant war as a Pyrrhic victory for humanity and their new found Sangheili allies - the majority of the Covenant Loyalist military having been defeated at Delta Halo by the Sangheilian Fleet, and the rest annihilated by the joint Elite-UNSC forces at the Ark. This victory came in time to save the human homeworld, thanks to the actions of the Arbiter and SPARTAN John-117.
Humans are warm-blooded mammals who give birth to live offspring, and nourish their offspring with milk. They have five fingers, one being an opposable thumb, which a few Covenant species do not have. It was a major part in helping humans dominate on Earth. Their circulatory system is closed and consists of one heart and a network of blood vessels and red blood due to the iron-based hemoglobin of humans, as well as two lungs which breathe mainly a nitrogen-oxygen-based atmosphere. Externally, they have more hair than most Covenant species. Their eyes have more pinpointed pupils allowing for good vision, and their sense of hearing can detect very low pitch sounds. However, their sense of smell is fairly poor. They are omnivorous, meaning that they will eat both meats and plants, as well as consume high calcium foods, such as the milk of other animals, in great quantities. They have a more developed bone structure for protecting organs.
Humans are lean and possess relatively little muscle tissue. The relatively low power output of the human anatomy translates into a low upkeep for their sustained bodily functions. With a metabolism well-suited for the moderation of internal body temperature, less recovery time is required from physical exertion compared to other species. Though potential prey would easily out pace them at first, by pure stamina alone, early humans were able to wear down their quadruped game as it succumbed to heat stroke far sooner than they would.
In the 22nd century, Earth was deemed overpopulated, jump-starting the colonization programs of the time. The population of known human settlements preceding the Human-Covenant war would amount to 39 billion humans according to the UNSC and Halsey's records and estimates. After twenty seven years of war with the genocidal Covenant, Cortana approximated the death count to 23 billion (16 billion remaining).
Halo is a military science fiction first-person shooter video game franchise managed and developed by 343 Industries, a subsidiary of Xbox Game Studios. Halo was originally developed by Bungie Studios. The series centers on an interstellar war between humanity and an alliance of aliens known as the Covenant.
The games in the series are critically acclaimed, with the original considered the Xbox's "killer app".