United Nations Space Command (Halo)

The United Nations Space Command is the main faction of future humanity, spanning multiple worlds besides Earth. Formed in the 2160s, during a period when remnants of old cultural ideologies clashed over supremacy in the Solar System, the UNSC primarily served as an overseer of United Nations military operations in space. After initiating massive militarization propaganda throughout its off-world colonies, the UN, through the UNSC, defeated Neo-Communist and Neo-Fascist forces in a conflict generally known as the "Interplanetary War", consisting of several side-battles that took place on Mars, the Jovian Moons and the South American Rain forests. Although the war brought a great deal of suffering to both the colonial population and the residents of Earth, it also united humanity's military forces into a common armed force by the end of the 22nd century: the UNSC.

Before the Covenant's attack on Harvest, humanity is in turmoil, with the more remote colonies fighting for independence from the UNSC. To help quell the revolts, the UNSC commissions the SPARTAN Project, which creates elite supersoldiers to stealthily eliminate insurrectionists. When the Covenant began decimating the outer colonies, these Spartans became humanity's best hope against the technological superiority of the aliens. By Halo: Combat Evolved, Sol—whose location is kept secret from the Covenant—is the last remaining Human bastions; it falls under attack during Halo 2. The end of the Human-Covenant war only comes after one of the Spartans, MCPO John-117, helps to eliminate the Covenant's leadership and destroy the Flood. Most of sol system's civilian population which numbered about 30 billion was saved and that was 60 percent of the human population at the end of war  was about 54 billion. But at a price of millions of civilians who died due to the covenant plasma bombardment in eastern Africa. The Covenant reduce Humanity's population by almost two third's which killed 106 billion of human population where it was before the start of the war The reasons that Sol's population was saved. Was due to UNSC defenses and misdirection of covenant forces by the Prophet of Truth and the Brutes under his command..

Military
The UNSC is the military arm of the Unified Earth Government, or UEG. According to Halo story architects Frank O'Conner and Robt McLees, during the events of Halo the UNSC exercises considerably more power than its civilian counterpart. The UNSC is divided into multiple subbranches, very similar in structure to the current-day US military, as well as including medical and science divisions.

The commanding offices of the UNSC military are CENTCOM (Central Command), and HIGHCOM (High Command). The Office of Naval Intelligence (ONI) is the most secretive branch of the UNSC, responsible for gathering intelligence and distributing propaganda. In the novels The Fall of Reach and Ghosts of Onyx, ONI is responsible for the development of the SPARTAN II and SPARTAN III supersoldiers under the supervision of Dr. Catherine Halsey and Colonel James Ackerson, respectively.

The primary force in the UNSC, the UNSC Navy is seen to use a varied fleet of warships, ranging from retrofitted Colony ships and fighters to stealth ships and cruisers. Among the UNSC's armaments are coilguns known as "Magnetic accelerator cannons", or MAC guns. First mentioned in Halo: The Fall of Reach, the cannons play an important role in Halo 2 as part of Earth's defense grid. Aboard Navy ships are the UNSC Marine Corps, seen throughout the games and novels as the primary ground force of the UNSC. One of the UNSC's Special Forces units are the Orbital Drop Shock Troopers (also known as "Helljumpers"), which specialize in orbital combat insertions. As characterized by author William C. Dietz in Halo: The Flood, the future Corps shares thematic similarities to the present-day United States Marines. The UNSC also has an Army, which serves as a ground defensive force within the UNSC military along with the UNSC Air Force, and in the novel Halo: Contact Harvest train militias on each colony, in part to stem insurrections against the UNSC on the colonies.

Interplanetary War
The UNSC has its roots in World War II, which would form its parent organization, the United Nations. The UNSC was actually formed and fashioned as the result of a series of brutal conflicts across the Solar System and Humanity's space confines between 2160 and 2164, most prominently among them the Jovian Moons Campaign, The Rain Forest Wars, and a series of battles on Mars. The United Nations Space Command, as organized and orchestrated as it seems is actually an emergency military government formed in such strife. These encounters were centered, around U.N. clashes with dissident political movements, the most important of which were the "Koslovics" and the "Frieden". More specifically, the Frieden movement was a fascist organization based on the Jovian Moons, though they received some secret backing from some corporations operating in some where, while their ideological opponents, the Koslovics, formed a Marxist-Leninist group centered around the leadership of Vladimir Koslov.

The war began with an attack on U.N. Colonial Advisers on the moon of Io, one of the moons of Jupiter, but would spread to Mars and parts of South America in the Rain Forest Wars. These events culminated in a U.N. buildup in the 2160s, which would result in the second of the great reforms, the first being from the League of Nations into the U.N. The second reformed the U.N. from a largely diplomatic organization to a permanent United Earth Government as an ultimate power to lead the human race by 2170.

Colonization
The four-year long war put the spotlight on problems facing the overpopulated planet, and the Rain Forest Wars also exacerbated the problems relating to food distribution. The ensuing famine and societal problems related to the post-war population boom providing the spark to change the political nature of governance on Earth and elsewhere, leading to the political system seen in the 26th Century.

These pressures also helped make space colonization seem more attractive in later centuries and emigrating in system off-world colonies, as the Unified Earth Government would sign off on a colony ship program that was revealed in 2310 to ease the burden on the ailing home world. This would not have been possible without the invention of the Slipspace Shaw-Fujikawa drive in the late 2200s, which allowed the ships to travel far greater distances than ever before.

It took 52 years before the first colony ship, the Odyssey, was launched by the time of it's completion the in-system off-world colonies could also became like earth could not hold the human population burden for earth as they two become over populated also so the completion of the first colony ship fleets came just in time for the human race, and what became the so-called Inner Colonies were not fully colonized until the end of the 24th century. The apex of human colonization would come in 2492, when more then 800 worlds were under human control and were at various stages of development. By this time, a ring of Outer Colonies was providing the UEG with the raw materials that made the macro-economy work; the political power, however, remained with the before mentioned 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. Fearing the consequences of the breakup of the interstellar empire and seeing the benefits of avoiding all-out war to defend their hold on the colonies, the Earth government would embark on the SPARTAN-Is, the predecessors to the SPARTAN-II program in 2491, beginning with the ORION Project.

The Human-Covenant War
2525 marked the most important turning point in human history; it would mark the beginning of the great technological advancement, the unification of a divided and fractured human race, and the first contact of humanity and an extra-terrestrial intelligence, the Covenant. It would also see alot of the Earth government's 800+ colony worlds glassed, and billions of colonists and military personnel slaughtered by orbital plasma bombardment and planetary invasion, known as glassing. Thus began the Human-Covenant War with the First Battle of Harvest.

Stemming from the chance encounter of human and Covenant] forces at Harvest, the first contact made between humanity and the Covenant involved the ship ''Minor Transgression', and was less peaceful than the second contact made between the two factions. A less aggressive meeting between representatives of the two factions took place on the fields of Harvest, but the peaceful meeting soon turned into a blood bath, with the Covenant] claiming the planet for the numerous "Forerunner relics" present (unaware that the humans are the relics), slaughtering most of the colony's population.

On April 20, a scout ship, Argo, was sent to investigate the cessation of communications between Harvest and the rest of the UEG's colonies. Before being destroyed by Covenant forces, it discovered that everything on the planet had been completely incinerated, and the surface covered by fields of magma, leaving nothing alive. Soon after, Battlegroup 4, consisting of the frigates Arabia and '[Vostok and the destroyer Heracles'', was sent to find out what had happened. On October 7, the battle group dropped out of Slipspace and to Harvest. In orbit around the remains of the colony world was a single alien ship which proceeded to attack the battle group, destroying all the ships except one. Intercepted communications identified the enemy as the Covenant, a caste-driven, theological organization made up of several alien species. The message "Your destruction is the will of the gods...and we are their instrument" was broadcast in perfect English.

Since the later Second Battle of Harvest in 2526, where a huge human fleet led by Vice Admiral Preston Cole barely won against a smaller Covenant fleet in a symbolic "victory" for humanity, the humans' grip on their territories declined significantly in the course of their struggle. Of the more than 800 colony worlds, the Covenant had managed to glass the alot of the Outer Colonies, and a portion of the Inner Colonies.

By this time, the UNSC overrode the UEG, and thus the central civilian authority throughout the human worlds and Earth itself. Although the central government was more willing to step down, the Colonial Administration was far more reluctant to this idea, and thus the UNSC stripped it of most of its power. By the middle to late stages of the war, the government of humanity could be more accurately described as an "emergency military" government.

By 2552, the UNSC Navy, Marine Corps, Army, Air Force, and Militia, outnumbered and out-gunned, had managed to slow down the Covenant's inexorable progress through former human space, but the situation was dire. In desperation, HIGHCOM ordered a high-risk op, sending the SPARTAN-II super soldiers, the best soldiers ever fielded by humanity, to insert into Covenant space, capture a high-ranking Prophet, and return to UNSC space in an attempt to ransom for a truce. Before the operation began, the Covenant found and destroyed the planet Reach, killing most of the Spartans and a large portion of the UNSCDF, inadvertently stopping the operation and rendering most of the SPARTANs MIA. This became known as the Battle of Reach

A single ship, the UNSC Pillar of Autumn| managed to escape the planet, with two SPARTANs on board, Linda, who was presumably dead in the Battle of Reach and the Master Chief. The ship followed coordinates derived by the A.I. Cortana to a ringworld known as Halo. There the Master Chief destroyed a large Covenant fleet and the ringworld itself. He also encountered a parasitic lifeform known as the Flood, the species that the ring, Halo, had been built to starve. The major side-effect of the activation of the ring would lead to the extinction of all life within three radii of the galactic center. The Master Chief destroyed the ring, believing it to be too powerful, by detonation of the reactor of the Pillar of Autumn. After hijacking a Covenant Flagship known as the Ascendant Justice, the SPARTAN reunited with the remaining survivors from Halo and the destruction of Reach and attacked a force of Covenant ships in [[Operation: FIRST STRIKE, one of the most successful UNSC operations against the Covenant in the entire war.

By October of 2552, the Covenant had haphazardly discovered the position of the human home world, Earth, and sent a preliminary task force there, believing it to be the location of the Ark, an ancient[Forerunner relic. They encountered staunch resistance, and were initially fended off. Further complications arose from the political and religious crisis that emerged in the wake of a UNSC operation to assassinate the Prophet of Regret, and the secession of the Sangheili from the hegemony, leading to the Covenant Civil War, further throwing the Covenant into chaos. Nevertheless, by November, what was left of the Covenant Loyalists had subjugated large parts of Africa, devastating much of the planet. Only their retreat through a Forerunner portal in Africa, and the arrival of the Sangheili Fleet, stopped the utter destruction of the UNSC and [[Earth itself.

The UNSC and Elite forces launched a joint operation to destroy the Covenant Loyalists once and for all at the Ark, stopping the installation from firing the Halo Array, killing the Covenant's last remaining leader, the Prophet of Truth, and destroying the bulk of the Loyalists' remaining forces. On March 3, 2553, the Human-Covenant War officially ended in a victory for the UNSC and the Covenant Separatists, but at a high price, with most major military outposts destroyed except for Earth as well as many colonies (although it seems that most of the colony worlds were not glassed during the war, with only seventy-six worlds known to have been totally destroyed). It is presumed that millions of UNSC personnel and untold billions of human civilians had been killed from 2525-2553.