The Human-Covenant War, also known as The Great War, was a major interstellar conflict pitting the Unified Earth Government and its United Nations Space Command against the Covenant Empire during the mid-26th century between February 11, 2525 and March 3, 2553. There were two additional factions of the conflict; The Flood and a small number of surviving Forerunner constructs. Both additional factions proved to be invaluable to the efforts of humanity, as the information taken from Forerunner constructs and the Flood invasion of High Charity were helpful in splitting the Covenant apart in October of 2552.

The war was instigated by the Covenant, whose Prophets discovered that humans were directly related to the Forerunners. In order to keep the Covenant intact, war was declared against humanity. Over the next few decades, the Covenant, with superior firepower, tactics, and technology, overpowered humanity on hundreds of worlds, including heavily defended strongholds such as Reach. The Humans would only win scattered and costly victories, most of which the Spartans contributed to immensely.

The conflict was closely connected with, and the cause of, the Covenant Civil War, both of which resulted in the final defeat of the Covenant Loyalists and Flood. The official cessation of hostilities occurred on March 3, 2553.[5] The war was incredibly costly to both sides, with over twenty-three billion humans and billions of Covenant killed during the hostilities and further heavy casualties during the Flood plague. The war ultimately lasted for a total of twenty-eight years. Now Your in the fight.


History Of War: Declaration of war (2525)
Main article: First Battle of Harvest

Staff Sergeant Johnson leading Colonial Militia during the Covenant invasion of Harvest.

Humanity and the Covenant first came into direct contact in February 3 2525, when a Kig-Yar Frigate, the Minor Transgression, discovered a human ship that had dropped out of slipspace due to a problem with the Shaw-Fujikawa Translight Engine. The Kig-Yar raided that ship and another one. The Harvest shipping operations AI, Sif, found out about the raids as a result of the distress beacon from the ships (although she and an undercover ONI spook on Harvest thought that Insurrectionists, not aliens, were behind the raids). The spook set a trap for the Kig-Yar which resulted in a minor skirmish between Staff Sergeants Nolan Byrne and Avery Johnson, and the Kig-Yar privateers. When the Covenant returned with another ship and a contingent of Brutes, the UNSC proposed a meeting (via pictogram) to trade. The Covenant met the UNSC on Harvest, but were only interested in claiming the relics that the Luminary had detected on Harvest, completely oblivious that the humans were the "relics" in question. The meeting was botched after Osmo, a member of the Colonial Militia, was attacked by a nervous Grunt who was part of a second Covenant force sent to look for the relics. As a result, a firefight erupted between the two groups and the Covenant retreated back to their ship.

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. This "crusade" would eventually turn into mass genocide.

The campaign to exterminate Humanity was an attempt by the Prophets to keep their power, under the disguise of a holy crusade. The Prophets found out that the Forerunner objects that the Luminary revealed on Harvest were actually Humans (which the Prophets interpreted as meaning that the Humans were descendants of the Forerunner, or possibly surviving Forerunner). Initially, the Covenant interpreted the glyph from the luminary as "Reclamation". Startlingly, the Forerunner AI 05-032 Mendicant Bias revealed that the interpretation was wrong: the glyph meant "Reclaimer". The Prophets Regret and Truth realized that if the Humans were actually Forerunners, then it was possible to be left behind when the Great Journey occurs. This stood in contradiction to the Covenant religion, which held that no one would be left behind in the Great Journey. The Hierarchs, recognizing that this truth would destroy the Covenant, declared war on Humanity, hoping the truth would perish with their newly-declared foe.

The first battle of the war was the extended though one-sided ground battle which took place on Harvest, in which the UNSC managed to delay the Covenant long enough to evacuate many of Harvest's civilians. Eventually, the Covenant used their capital ships to glass the planet's surface.

Open war (2525-2552)
From that point on, the Covenant continued to attack and destroy the Humans where ever they were found, using their Luminaries to find Human worlds. Though the UNSC forces fought bravely, their inferior technology and strategic competence meant that even a close victory even with the aid of the Spartans 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 around the planet, and then reduce the planet's surface to glass with orbital plasma bombardments, sometimes using the Covnenant army to soften up the UNSC Army. The few victories achieved by the UNSC were due to special tactical maneuvers and the spartans, as human missiles and magnetic acceleration weapons were unable to compete with Covenant energy shields, plasma torpedoes and tactics. Over twenty-seven years, the Covenant whittled down the UNSC planet by planet.

Realizing the threat posed to humanity by the Covenant, the UNSC Colonial Military Administration gave Vice Admiral Preston Cole the command of the then-largest fleet in human history with orders to retake Harvest. Cole retook Harvest in 2526, and then spent five years chasing the Covenant around the Outer Colonies, fighting them and scoring victories at Alpha Aurigae, XI Boötis A, and Groombridge-1830. Meanwhile, the Covenant returned to Harvest, determined to recapture the planet. This led to a five-year long series of engagements on Harvest between the Covenant and the UNSC.

The Apex and the Arbiter (2531)
Despite their major numerical and technological advantages over humanity, by 2531, the Covenant High Prophets had realized that the task of destroying an entire sapient species had a logistical burden beyond anything that the Covenant military could muster without leaving Covenant space defenseless.[6] In spite of the UNSC's inferiority in comparison to the Covenant, the Prophets apparently considered their armed forces to be powerful enough to pose a threat to the Covenant proper. The Prophet of Regret dispatched an Arbiter to Harvest to claim a Forerunner artifact buried under the north pole of Harvest.

Preston Cole counter-attacked by leading a fleet composed of the UNSC Spirit of Fire and the UNSC Prophecy back to Harvest after receiving a message from an ONI Prowler. The battle was a human victory despite major casualties. Upon discovering that the Covenant, under the command of 'Moramee, had excavated Forerunner artifacts in the northern polar region, Captain James Cutter deployed ground forces to remove the Covenant occupation. After a heated fight on the surface, the UNSC forces were able to examine the artifact, apparently some kind of star map, and realized that information from the map had led the Covenant to another UNSC colony: Arcadia.
The UNSC Spirit of Fire engages a Covenant destroyer in the Flood-Controlled Shield World.

As predicted, the Covenant followed the information from the artifact to Arcadia. The Covenant wished that the planet would contain more Forerunner artifacts for them to claim, and while they only found a complex of ruins, information garnered from them led them to a Shield World. The Spirit of Fire followed and removed the Covenant presence from the planet. However, 'Moramee's capture of an important civilian researcher forced Captain Cutter to pursue the Covenant to the newly discovered Shield World without reinforcements.

On the Shield World, the crew of the Spirit of Fire eventually discovered that the Covenant needed Professor Anders to activate the Apex and claim the huge fleet of Forerunner starships held there. A group of Marines, together with SPARTAN-II Red Team, rescued the researcher and destroyed the Shield World. The Arbiter was also killed by John Forge during the battle though the Prophet of Regret escaped.

SPARTAN-III (2531)
Despite the well-publicized victory at Harvest, the UNSC was already on the way to losing the war. A number of colonies had already been glassed by the Covenant or abandoned, including Eridanus II, Dwarka, and Chi Ceti IV. The UNSC's sole hope apparently lay with the SPARTAN-II Program, a secret program to create super soldiers originally to combat Insurrectionists. However, there were not enough Spartans to turn the tide of the war in favor of humanity. Recognizing this, the Office of Naval Intelligence authorized the creation of the SPARTAN-III Program. The brainchild of Colonel James Ackerson, these Spartans would be trained with a greater emphasis on stealth and teamwork, and would be sent on missions against high-priority targets that would be impossible even for elite units.

Crisis (2534-2535)
With the majority of the Outer Colonies glassed or abandoned, the UNSC faced an economic crisis as some of their Agriculture Worlds had been destroyed, leading to food shortages. On Charybdis IX, food riots broke out. Meanwhile, Covenant forces began to encroach on the Inner colonies. In response, the UNSC issued United Nations Space Command Emergency Priority Order 098831A-1, "The Cole Protocol". It stated that no UNSC vessel may lead the Covenant to Earth or any other human population center. Furthermore, all movement through space was restricted to UNSC Navy vessels. Insurrectionist attacks increased in the face of what they saw as a removal of their right to freedom of movement. Another development was the discovery of Insurrectionists using Covenant weapons modified for human use. The UNSC saw this as a threat to security as the weapons may have been carrying Covenant homing beacons. The Covenant saw it as heresy that humans would modify their weapons, and the Prophet of Regret dispatched Thel 'Vadamee to destroy the source of the modified weapons: The Rubble.

Fleeing from the Battle of Charybdis IX, the UNSC Midsummer Night chased an Insurrectionist freighter to the Rubble and discovered that the Insurrectionists there had actually formed an alliance with a colony of Kig-yar. The Jackals were supplying the weapons and the Insurrectionists were modifying them. The crew of the Midsummer Night, including its captain, Lieutenant Jacob Keyes, were captured, but later escaped and helped SPARTAN-II Gray Team and the Rubble's citizens stop an assault from the Kig-yar leader, Reth, and 'Vadamee's forces. It later transpired that the Prophet of Truth had ordered the Kig-yar to ally with the humans so that they could discover the location of Earth from stolen navigation data of through tracking devices in the weapons. Through this, the Covenant found two more worlds to attack.