Human-Covenant war

The Human-Covenant War, also known as The Great War, was a major interstellar conflict between the United Nations Space Command and the Covenant during the mid-26th century.

The conflict was closely connected with, and the cause of, the Covenant Civil War; both of which proved instrumental in the final defeat of the Covenant and Flood on March 3, 2553.

Background
Humanity and the Covenant first came into direct contact in 2525, (twenty-seven years before the events of Halo: Combat Evolved), when the Covenant attacked the UNSC Outer Colony world Harvest. The Covenant had been covertly studying the human race for some time prior to that, as they had knowledge of the English language as well as the location of at least some human worlds. The Prophets declared humanity to be an affront to their gods (supposedly because humans inhabited and 'defiled' areas which were once Forerunner), and called for a crusade against the Human species. They used their capital ships' plasma weaponry to vaporize the surface of the planet, turning the crust into molten glass, a process which would become known as "glassing." From that point on, the Covenant continued to attack and destroy the humans wherever they were found. Though the UNSC forces fought bravely, their inferior technology and numbers meant that even a close victory was far from guaranteed. The Covenant also had an advantage in that they didn't need to fight planet-side to destroy the enemy; their ships simply needed to destroy the humans' space-borne defenses and any other threats planet-side, and then reduce the planet's surface to glass with orbital plasma bombardments. The few victories achieved by the UNSC were due to special tactical maneuvers, as human missile, and magnetic acceleration weapons were unable to compete with Covenant energy shields and plasma torpedoes. Over twenty-seven years, the Covenant whittled down the UNSC planet by planet until they destroyed the last major military installation outside of Earth, the world known as Reach.

Their first truly costly defeat was on and around the Forerunner ringworld of Halo. Here, the human survivors from the Halcyon-class cruiser, the UNSC Pillar of Autumn, managed to form an effective resistance. Unwilling to risk damaging the sacred ring, the Covenant was forced to fight the humans on Halo's surface rather than using its usual bombardment tactics. The Covenant found the Humans uncannily adapted to Halo's environment and very adept at fighting on the surface, with Human firearms and vehicles proving effective despite their technological inferiority. Unable to counter the guerilla tactics employed by the humans and the unexpected emergence of The Flood, the Covenant was soundly defeated in numerous raids, including one instance when the humans boarded their grounded cruiser, the Truth and Reconciliation, and successfully escaped with a group of captives, including the captain of the Pillar of Autumn, Captain Jacob Keyes. During the course of the battle, the human known as the Master Chief discovered the true nature of Halo and proceeded to destroy the ring, much to the Covenant's horrified dismay.

According to the novel Halo: First Strike, shortly after the defeat at Halo, the Covenant had amassed a large fleet that appeared to be intended to assault Earth. It is explained in the audio drama, ilovebees, that the Covenant discovery of Earth was an accident after the Pious Flea had been intercepted by the UNSC stealth ship Apocalypso. After retrieving a Forerunner artifact, the Apocalypso made a Slipspace jump directly to Earth. When the ship tumbled into real space and crashed on the moon, the Pious Flea sent a message to the heart of the Covenant military, containing recon data, photos, starmaps, and the coordinates to the Forerunner Artifact, which is now on Earth. The events of Halo 2 apparently contradict the novel in explicitly stating that the Covenant had not identified Earth as the Human homeworld. However, the Unyielding Hierophant's fleet was never expressly identified to be intending to assault Earth; this is merely a reasonable assumption made by the human forces upon discovery of the fleet's destination of Sol. This leaves the exact nature of the fleet's mission uncertain, as there is no definitive proof that the Covenant were intending to attack a human homeworld. The surviving humans, however, believed this fleet to be a direct threat to Earth, and, using a captured Covenant flagship, lured the fleet into a trap and destroyed it.

A few weeks after this defeat, the High Prophet of Regret led a small fleet of fifteen ships to Earth, supposedly in order to locate a Forerunner artifact known as the "Ark." Though hopelessly outgunned by the UNSC's new orbital defense grid, the Prophet of Regret's flagship managed to break through the human defenses to New Mombasa. The Covenant ground troops quickly spread through the city, destroying both military and civilian resistance, but a counterattack by the Marines and the Master Chief drove them back. His fleet having been destroyed in orbit when he landed, Regret was forced to retreat. His carrier jumped into Slipspace from within the city, destroying it and clearing the area for a later Covenant excavation of the Ark.

Unfortunately for Regret, a single Human ship, the In Amber Clad, had followed them through their own Slipspace rupture to Delta Halo. With the orders "Find out why he came to Earth; why he came here," the Master Chief was hard-dropped with a compliment of Orbital Drop Shock Troopers to Delta Halo's surface. Led by the Chief, the Humans forced their way through Regret's forces until they had reached the Prophet himself. At that moment, High Charity, having learned of Delta Halo, arrived and launched multiple waves of Phantom dropships to aid Regret, but they were too late. The Chief assaulted and killed Regret, and the Covenant fleet recalled the Phantoms in favor of bombarding the area. It would seem they succeeded in "killing" Master Chief by burning away the building, as he came inches away from getting incinerated by the massive plasma beam glassing the area, plummeting down into the lake below.

Meanwhile, the majority of the human forces on In Amber Clad had travelled to Delta Halo's Library to obtain the Index, the key to firing Halo. Originally, the Covenant had been unaware of the Index's importance, but luckily for them, the Arbiter had obtained the Monitor of the first Halo while destroying a heretical sect. The Monitor, known to the Covenant as an Oracle, told the Prophets of the Index and the Arbiter was sent to retrieve it. The mission was complicated though by the unexpected release of the Flood. Despite this, the Arbiter successfully reached the Library and prevented the humans from claiming the Index. Just as Miranda Keyes claimed the index, the Arbiter stole it from her, kidnapping her and Sgt. Johnson. However, then Index was stolen from the Arbiter by the Brute Chieftain Tartarus, who under the Prophets' orders then attempted to kill the Arbiter. With the Index secure, the Prophets then ordered the Brutes to begin eradicating the Elites, thus starting the Covenant Civil War.

Following the Flood infestation of High Charity at the end of Halo 2, the High Prophet of Truth led the remaining loyalist fleet to Earth to complete what the previous mission to Earth had not. Little did he know that Spartan 117, Master Chief, had stowed away with him. By the time Truth arrived at Earth, a full-scale war in space and on the ground was underway between UNSC and Covenant fleets, and in Halo 3 it is indicated that the Covenant are in the process of conquering the planet and occupying the world.

United Nations Space Command
Leaders: HIGHCOM

Homeworld: Earth (intact at the end of the war)

Military Forces: Exact numbers are unknown.

The Covenant
Leaders: The High Council

Homeworld: multiple worlds

Capital City: High Charity (destroyed by the Master Chief after being turned into a Flood Hive and crashing on the Ark)

Military Forces: Exact numbers are unknown.

Confirmed Casualties
The following is a short list of confirmed losses for both the Humans and the Covenant. These numbers are pulled from the battles that took place and are only an estimation; the true numbers while unknown, are probably a lot higher for both sides.

Covenant
Ships: Over 880

Military, Civilian, Etc.: At least 500.6 million.

The Unyielding Hierophant

High Charity

Joyous Exultation

Malhiem

Human
Ships: Over 180.

Worlds glassed: A minimum of 210 worlds.

Military, Civilians, Etc.: Over 1.006 billion.

2525

 * The Prophet of Truth discovers humanity's relation to the Forerunners, and instead of risking a bloody civil war that this knowledge could cause, he immediately demands the annihilation of all humanity.
 * The UNSC makes first contact with the Covenant at the UNSC colony world Harvest. The Covenant destroy the colony without warning or provocation.
 * The Battle of Chi Ceti takes place.

2530

 * The Covenant destroys the UNSC colony world of Eridanus II.

2531

 * Battle of Harvest. The UNSC and Covenant meet in ship-to-ship combat for the first time; the Covenant are outnumbered and outgunned, nevertheless the battle is a close victory for the Humans.

2535

 * The Covenant destroys the UNSC colony world of Jericho VII in the Battle of Jericho VII.
 * In the course of four short years, UNSC forces have been hammered, despite excellent leadership and tactical brilliance. It is simply a matter of being outgunned; Covenant kill ratios tend to top three to one in ship-to-ship combat. By 2535, virtually all of the Outer Colony worlds have been glassed by the Covenant.

2536

 * Covenant forces begin to swarm into the Inner Colonies. For several years the war falls into a pattern: humans win isolated battles, typically during ground operations, but at a horrible cost. In space combat, the humans are losing at a precipitous rate, and one by one, the colonies fall.

2537

 * The Battle of New Harmony
 * The Battle of New Constantinople
 * The Siege of the Atlas Moons
 * Operation: PROMETHEUS: Pyrrhic UNSC Victory. Spartan-III Alpha Company is killed by Covenant forces

2544

 * The Battle of Miridem

2545

 * Operation: TORPEDO: Pyrrhic UNSC Victory. All but 2 of Spartan-III Beta Company is killed by Covenant forces

2549

 * The Siege of Paris IV

July

 * Battle of Sigma Octanus IV in the Sigma Octanus System. It is the UNSC's single greatest victory since Harvest. The Covenant, however, gain what they are looking for: the location of Installation 04. They also determine the location of Reach.

August

 * Battle of Reach. In the largest naval battle yet in the war, 314 Covenant ships destroy 152 UNSC ships and 20 MAC gun platforms around Reach, and win a major victory, destroying a great UNSC military stronghold, although at a horrible cost to themselves; at least 2/3's of their fleet is destroyed.

September

 * The Battle of Installation 04. A single UNSC ship, the UNSC Pillar of Autumn escapes to Installation 04. After four days of hard fighting, the Covenant discover the Flood organism and Forerunner constructs, hampering their efforts to control the installation. The melee ends with Installation 04 destroyed with only a handful of survivors.
 * Operation: FIRST STRIKE. Six SPARTAN-II supersoldiers are able to rout and destroy a fleet of 500 Covenant starships preparing to jump to Earth. This is the single greatest victory for the humans during the entire war and the single greatest loss to the Covenant.

October

 * The First Battle of Earth. Though a relatively small and lopsided battle; 15 Covenant ships fighting 75 UNSC vessels and 300 MAC platforms, the event is significant in that the Covenant discover the location of Earth. The UNSC wins the fight.
 * The Battle of Installation 05. A single Covenant ship survives the battle of Earth and retreats to Installation 05. It is pursued by a single UNSC frigate, the UNSC In Amber Clad. Again, a massive fight ensues between the UNSC, Covenant, Flood, and Forerunner Constructs. The Flood appear to take control of the Installation. The Prophet of Regret is assassinated by Spartan-117.
 * The Civil War of the Covenant begins. Covenant forces are thoroughly divided between the Elites and the Brutes. Every race in the Covenant takes sides. The Prophet of Mercy is later killed by a Flood Infection Form.
 * The Second Battle of Earth. The Brute faction of the Covenant returns to Earth in force, apparently conquering Africa. Later, during the next months the Marines, with help of the Separatists, pushed back the loyalist invaders.

November

 * The Battle of Onyx. The destruction of Installation 04 triggered Onyx sentinels to appear. The Covenant followed their stolen destroyer called Bloodied Spirit, which a group of SPARTAN-IIs(Blue Team) were ordered to take to Onyx by Lord Hood in order to aid Dr. Halsey and the other Spartans. The battle ends with the destruction of all Covenant and UNSC vessels (with the exception of the UNSC Dusk).
 * Covenant Civil War - The battle continues.
 * The Second Battle of Earth - The battle continues.
 * Battle of Installation 00
 * All Loyalist vessels destroyed over the Ark by the Seperatist Fleet
 * The final Covenant religious leader, the Prophet of Truth, is executed by The Arbiter with help from the Flood. The Master Chief stops the Ark from firing the Halo Rings.
 * High Charity is destroyed by the Master Chief after he blasts the city's main reactors causing them to go critical.
 * The Second Battle of Installation 04. This battle was the shortest but most crucial battle in the Great War. Though the Covenant were defeated, the Flood still posed a major threat. During the battle the Monitor and the new Alpha Halo’s sentinels turned on the Master Chief, Johnson, the Arbiter, and the Elites. The Master Chief and the Arbiter managed to defeat the Monitor and activate the ring. The activation eradicated all Flood in the vicinity, doing a "number on the Ark," as Cortana put it, and destroyed the ring itself. These final events ended The Great War.

March 3

 * The war ends in a UNSC-Covenant Separatist victory. The victors erect a monument on a hillside near the Ark's Gateway to commemorate those fallen.