Post-Covenant War conflicts

Following the end of the Human-Covenant War in 2553, the Unified Earth Government and its United Nations Space Command became embroiled in another major conflict with a major remnant group of the former Covenant declaring itself as a continuation of the original hegemony.

In one of the first battles of the war, the resurgent Covenant attacked the human colony of Draetheus V, seeking to obtain a powerful Forerunner artifact held there. In 2557, the Covenant gained access to the shield world of Requiem, home to the Didact, a legendary Forerunner Promethean whose aid the Covenant sought to enlist in their campaign against humanity. The ensuing series of skirmishes led to the Didact's release and an alliance between the Promethean forces and the Covenant, who revered the Didact as a "living god". Covenant forces subsequently helped the Didact retrieve the Composer, and ancient Forerunner device with the power to wipe out mankind.

Although the Didact was later defeated by John-117 in a battle over Earth, the Covenant continued to occupy Requiem, searching for the Librarian. They contested the UNSC for control of the shield world again in early 2558; the drawn-out battle eventually culminated in the installation's destruction but not the defeat of the Covenant, who had already withdrawn most of their forces from Requiem. Additionally, they managed to capture a significant UNSC asset, Dr. Catherine Halsey, who was seemingly willing to collaborate with 'Mdama. Both the UNSC and the Covenant also ended up with a half of the Janus Key.

Historical context
While the final year of the Human-Covenant War was marked by clashes for newfound Forerunner artifacts and the revelation of humanity's birthright as chosen inheritors to the Forerunner civilization, yet more significant discoveries would follow in the wake of the conflict. Long-hidden details began to surface on the Forerunners themselves, as well as their relationship between humanity, and even the yet more ancient and enigmatic race known as the Precursors. These unprecedented findings would have an immediate influence on events in the modern times, acting as driving forces for not only renascent Covenant cults but also forces far more ancient.

Before the Forerunners first built the Halo Array, the human race was a great interstellar empire. During the course of their growth as a civilization, they encountered a terrifying threat: an extragalactic parasite known as the Flood. As the parasite ravaged their worlds and threatened to consume their entire species, humanity fled outwards from their home territory. As they did so, they attacked any Forerunner world where an infection had taken hold, neglecting to warn the Forerunners of the threat in favor of bombarding infected areas immediately. Ignoring their warnings about the dangers posed by the Flood, the Forerunners - led by the Ur-Didact and his Promethean Warrior-Servants - defeated humanity and forcibly devolved their civilization. However, the Forerunners were left vulnerable by the long conflict: their military had been weakened, and all information regarding the mysterious threat that humanity had been fleeing was lost. After a period of calm, the Flood returned, and the Forerunners were ill-prepared to fight back.

The Forerunner Builder rate had prepared for this eventuality, creating a number of ring-shaped superweapons known as the Halo Array. However, the Didact was reluctant to use these, and instead planned to use the Composer, a device capable of transferring organic consciousness to software, as a means to save the galaxy's populace from Flood infection. But the process was flawed, and those who underwent the process were unable to be re-uploaded to an organic form. This, however, suited the Didact's purposes: he would use the Composer to convert his Prometheans into mechanical warriors, later augmenting their numbers with converted humans to create a massive army to fight the Flood. In his view, this was both an elegant solution to the Flood problem and a means of neutralizing the human threat forever. However, his wife the Librarian was horrified by his actions, and sealed him inside the shield world Requiem, which was his base of operations. The converted Prometheans were left there to guard his Cryptum, and Requiem remained quiet for millennia after the Forerunners were wiped out by the Halo Array.

Contemporary situation
Although the death of the Prophet of Truth at the Ark in the endgame of the Human-Covenant War saw the ultimate defeat of the Covenant and humanity's truce with the Sangheili species, it was not long after the end of the war that rogue splinter groups, many of them still hostile against humanity, began to rise from amongst the remnants of the hegemony. With large numbers of former Covenant matériel at their disposal, it was inevitable that these disparate remnants would band together against their former enemy, against the best efforts of those who favored a policy of peaceful cooperation, an approach most visibly embodied by Arbiter Thel 'Vadam.

The figure who would ultimately give a face for the new Covenant was a former Sangheili Shipmaster known as Jul 'Mdama. Although 'Mdama had always resented humanity even in the wake of the human-Sangheili alliance, the ultimate catalyst for his quest against mankind came in the form of the death of his wife Raia, which 'Mdama blamed humanity for due to their involvement in the Sangheili civil war. During his time in ONI captivity on ONIRF Trevelyan, 'Mdama had learned that the Didact, a mighty Forerunner general with a hatred for humans, was trapped inside a Forerunner world known as Requiem. After escaping Trevelyan, 'Mdama began to gather followers in order to travel to Requiem and unlock the world's secrets, intending to use the Didact as a motivating force for his followers, but also a new spiritual voice for his people and a chance to exact vengeance on humanity.

Draetheus V
The hostilities began when a Covenant fleet led by Merg Vol invaded the UNSC research colony Draetheus V and its moon, X50, in search of Forerunner relics, beginning a major battle which marked one of the first missions of the UNSC Defense Force's newest branch and home of the SPARTAN-IV Program, the Spartan branch. The battle saw significant losses on both sides and the planet Draetheus V itself nearly destroyed by Merg Vol's use of X50, which was in fact a Forerunner superweapon with the capability to destroy planets. The main hostilities concluded with Spartan Sarah Palmer killing Vol and sabotaging X50's main weapon, bringing the Covenant's quest to a halt. However the Covenant remnant returned when a looping Forerunner code began emanating from X50.

Requiem and the Didact
"Time was your ally, but now it has abandoned you. The Forerunners have returned."

- The Didact

By 2554, Jul 'Mdama had already gathered formidable numbers of followers and a powerful fleet which discovered Requiem, but were unable to enter the thoroughly sealed shield world. In orbit above the planet, however, was the wreckage of the, carrying the legendary Master Chief, SPARTAN John-117, and his deteriorating AI companion Cortana, drifting in space since the end of the Covenant War in 2552. Upon discovering the derelict vessel in July 2557, 'Mdama's Covenant forces attacked the Dawn in hopes of deterring any potential efforts by the humans to access their shield world.

Entering Requiem
The reawakened John and Cortana defeated the advanced scouting teams and reactivated the Dawn's weapon systems manually, destroying a CRS-class light cruiser in the process. After scanning the vessel and detecting a Reclaimer, Requiem's automated systems pulled both the Dawn and the Covenant force surrounding it through the world's outer shell and down to the planet's surface. Recovering a Warthog, Master Chief and Cortana vowed to make their way back to Earth in order to find a cure for Cortana's escalating rampancy. They set out to find a way to contact the UNSC, circumventing the powerful jamming field surrounding the world.

Fighting through numerous Covenant hunting parties, Master Chief was attacked by advanced Forerunner defense drones which Cortana identified as Prometheans. Evading or destroying pursuit, John attempted to warn the approaching of the dangerous energy field that had disabled the Forward Unto Dawn.

After disabling two control nodes in Requiem's core, it became clear that a great threat had been imprisoned within Requiem. The Ur-Didact, the Forerunner's greatest warrior, remained in suspended animation within a Cryptum. Easily disabling John with his powerful abilities, he declared the return of the Forerunners as the galaxy's rulers and saviors. Humanity remained weak and unworthy in his eyes of inheriting the Mantle, a view rejected by his lover, the Librarian. Having always revered the Forerunners as gods, the Covenant quickly swore alliance to the Didact and his armies. The Didact viewed the Covenant as mere primitives, but permitted them to serve his cause, to prevent the ascension of the human race to galactic prominence.

Infinity arrives
Narrowly escaping the collapsing core of Requiem, the Chief and Cortana returned to the planet's surface only to find their warning to the Infinity came too late. The massive warship crashed more than 70 kilometers away, with a massive force of Covenant and Prometheans closing on their position.

Evading capture, John was successful in regrouping with a group of SPARTAN-IVs led by Commander Thomas Lasky. Recognizing the Chief immediately, Lasky asked John and Cortana to clear a landing zone so that Infinity's ground forces could fall back to the ship which had fallen under siege. Commandeering a Scorpion tank, John led the attack to the crippled vessel alongside Commander Sarah Palmer's Spartans. Using the UNSC's latest weapon, the Mantis exoskeleton, John rallied a force of nearby Marines and regained control of the ship's interior. After reinitializing the ship's secondary MAC guns and missile batteries, the tide turned in the UNSC's favor. Two CRS-class light cruisers and dozens of dropships were destroyed in the artillery barrage, while the Didact's Cryptum was forced to retreat.

With a momentary lull in the fighting, John was called to a strategy meeting with Andrew Del Rio, Captain of the Infinity. Skeptical of the threat of the Prometheans, Rio ordered an immediate attack on a Forerunner gravity well preventing the ship from leaving. A strike force of Spartans led by John was deployed with a Mammoth-class ultra heavy ground vehicle supporting the attack. Facing daunting odds, the UNSC was able to defeat a large armored strike force of Covenant and Promethean and disabled the gravity beam. Upon reaching his objective, John was confronted with a vision from the Librarian, who warned him of the Didact's true plans. After explaining their history to them, she provided John with a gift, a medical treatment to counteract the Forerunner's devolution of the human genome, and a means to resist the Didact's plan to enslave the human race once again.

Regrouping aboard the Infinity, Captain Del Rio dismissed the threat of the Prometheans and prepared the ship to depart the system. Defying direct orders, John took the increasingly unstable Cortana and departed the Infinity. Armed with a Pelican gunship provided by Commander Lasky, John launched several attacks on support pillars providing the Didact's Cryptum with shield and power, with the goal of preventing him from leaving the planet and attacking Earth and other colonies.

The Composer
This attempt ultimately proved unsuccessful, as the Didact left Requiem aboard his flagship, the Mantle's Approach, escorted by a flotilla of Covenant ships. Stowing away aboard a Lich, the Chief followed the Forerunner to Ivanoff Station, a UNSC research base orbiting Installation 03, the Composer's resting place. Sandra Tillson, a lead researcher aboard the base, helped guide John to the artifact amidst a swarm of Covenant attackers. Despite the Spartan reaching the artifact first, the Didact was successful in obtaining the Composer, tearing it out of the station's hull with a gravity beam. Testing the weapon, the Composer burned the crew of the station to ash, assimilating their minds to create even more Prometheans. The Master Chief's genetic enhancements rendered him immune to the device's effects.

Battle of Earth


With the Composer in the Didact's possession, the Forerunner was poised to deal a deathblow to Earth, and by extension humanity. Racing across the Mantle's hull aboard an F-41 Broadsword fighter, the Master Chief was surprised to find the Infinity, now under the command of Commander Lasky, and the rest of the Home Fleet ready and waiting for the Didact. John was able to destroy the ship's point defense guns, giving Infinity the chance to punch through the vessel's hull. Entering the breach, John fought his way to the Forerunner's location.

Despite the UNSC's best efforts, the Didact began to fire on Earth with the Composer, annihilating the population of New Phoenix, Arizona. Armed with a HAVOK warhead, John confronted the Didact for the second time. While John was unable to hurt the Forerunner with conventional attacks, the dying Cortana disabled the Didact's armor and immobilized him with hard light shackles. With the last of his strength, John used a pulse grenade to destroy the Forerunner's armor, sending him down into a slipspace rupture beneath the Composer. With time having already ran out, the Spartan detonated the nuclear bomb manually as a desperate last resort. The Composer and Mantle's Approach were destroyed, saving the Earth.

Using the last of her power, Cortana was able to translocate John away from the blast, saving his life at the cost of her own. Left adrift in space, he was later recovered by a Pelican. Aboard the Infinity, John rejoined Palmer and the SPARTAN-IVs, preparing for the inevitable battles ahead.

Return to Requiem


While their defeat at Earth proved a set back for the Promethean-Covenant alliance, it did not result in their defeat. Six months later, the Infinity returned to Requiem with a fresh complement of Spartans, determined to conquer the planet at any cost with the intent of studying the Forerunner relics therein. The Covenant ships in orbit around the planet were swiftly defeated and scattered, demonstrating the technological advancement of the UNSC since the end of the last war.

Significant numbers of UNSC military forces were deployed on Requiem, including detachments of Spartan, Marine, Navy, Air Force and Army forces on Requiem. Arriving on the planet's surface, Majestic, Crimson and other SPARTAN-IV squads began to disrupt Covenant operations across Requiem and recover Forerunner artifacts for study. The Covenant in turn made numerous attempts to destroy Infinity while also trying to gain access to the stored memories of the Forerunner known as the Librarian.

The campaign ultimately ended in Requiem's destruction when Jul 'Mdama set the planetoid on a collision course with the sun. Both sides evacuated the doomed system, each possessing their own half of the Janus Key. Also during this time Doctor Catherine Halsey seemingly defected to the Covenant.

List of appearances

 * Halo 4
 * Spartan Ops
 * Halo: Spartan Assault