Battle for Earth

"Something's not right. The fleet that destroyed Reach was fifty times this size."

- Lord Terrence Hood

The Battle of Earth was a massive ground, air and space engagement between the Covenant and the United Nations Space Command, which occurred on and above the planet Earth, inside the Sol System from October 20, 2552 to November 9th, when the Prophet of Truth's Dreadnought left Earth through te portal.

At the beginning of the battle, fifteen ships and their personnel, led by the Prophet of Regret were defeated by a much larger and more powerful human fleet and ground forces. The battle itself was caused by miscommunication and lack of co-ordination between members of the Covenant, specifically the failure of the Prophet of Truth to inform the Prophet of Regret that Earth was in fact very heavily defended. The lack of information available to Regret meant that he was surprised and outgunned by the human defences.

Background
The Covenant learned of Earth's location in the aftermath of the Battle of Reach. It is believed that the Covenant had retrieved its coordinates from a ruined unsecured UNSC navigation database crystal, on Reach Station Gamma. Because Earth was the home planet of the human species and also the political military center of the United Nations Space Command and one of the last massed pockets of heavy UNSC resistance, it became a primary target for the Covenant armada, who amassed no less than five hundred warships in deep space around the Covenant mobile space station Unyielding Hierophant, preparing a massive Covenant assault fleet to attack Earth in a single, decisive strike that would overwhelm Earth's defenses almost instantaneously. However, Cortana learned of the coordination of the Covenant war fleet around the Unyielding Hierophant, and a SPARTAN-II strike team led by SPARTAN-117 assaulted the space station, causing a cataclysmic reactor detonation that wiped out the Unyielding Hierophant and almost all of the aggregated Covenant fleet assembling for the strike on Earth, leaving only a few dozen damaged warships that were still intact, while the SPARTAN-II team escaped with minimal casualties, although the tenuousness of the operation led Cortana to later say in a UNSC report that they went to "hell and back".

While SPARTAN-117's team traveled back to Earth on the, reaching it in several weeks, the Covenant appeared to be extremely uncoordinated. The Prophet of Truth was aware of the Unyielding Hierophant's fleet's plan to strike Earth and knew Earth as a major UNSC stronghold, the Prophet of Regret was uninformed, possibly because of Truth's devious, social political plans for the Covenant. Regret's own fleet of two Assault Carriers and thirteen s dropped out of Slipspace, igniting the First Battle of Earth.

Beginning
"This is Fleet Admiral Harper, we are engaging the enemy!"

- Fleet Admiral Harper

The Covenant Fleet was detected while en route near Io, one of the moons of Jupiter. Probes were sent to investigate, but shortly afterward, the force of fifteen Covenant warships reverted from Slipspace just beyond the range of the UNSC perimeter MAC orbital installations in orbit around Earth. The TACCON was raised to Alpha 2 in response to the Covenant presence around Earth as alarmed UNSC orbital forces prepared to repel the incoming Covenant assault.

While the Covenant Fleet held its position beyond MAC range, Fleet Admiral Harper suggested a preemptive strike on the Covenant Fleet, but Fleet Admiral Lord Terrence Hood countermanded his order, ordering the UNSC fleet to hold and defend the Orbital MAC Platforms and wait for the Covenant Fleet to enter MAC range.

It should be noted that at this point in time, the Cole Protocol no longer applied to Earth. During Master Chief's return to Earth, a random jump had to be made because, while there was overwhelming evidence that the Covenant knew of Earth's location, there was no certainty. After the arrival of Regret the secrecy of Earth's location had been lost, so UNSC forces could make slipspace jumps directly into the Sol System.

Covenant Assault
The UNSC possessed three hundred Orbital MAC Platforms, sufficient firepower to level the Covenant fleet in a single salvo when they entered range. However, Regret's fleet launched waves of Covenant Boarding Craft: small, nimble, fast-moving craft that would be difficult to track with the large, cumbersome Mark V Magnetic Accelerator Cannons that were the UNSC's primary defense. They were able to penetrate the UNSC fleet and dock with multiple MAC orbital installations, including Athens Station, Cairo Station and Malta Station. The Covenant appeared to target each installation with no less than half a dozen boarding craft. Despite the fact that the Athens and Malta were deeper into the UNSC formation, those were among the first installations to be boarded, while the Cairo was attacked shortly afterward by Boarding Craft that docked all across the station. These Boarding Craft started deploying hundreds of Covenant troops, including Elites, Drones and Grunts that overwhelmed most of the naval personnel and Marines stationed in the axial sections of Cairo Station. Teams of Ranger Elites marauded across the exteriors of the Orbital MAC Platforms to prevent personnel from travelling through airlocks. While SPARTAN-117 led a UNSC counterattack on the Cairo, saving pinned-down teams of trapped Navy and Marine personnel from plasma fire, the Athens and the Malta were infiltrated internally and in the early stages of the First Battle of Earth, the Covenant planted a Bomb in each captured MAC installation. They then retreated in their boarding craft before blowing up both stations.

Meanwhile, on the Cairo, defusing the Covenant Bomb had become a primary objective. SPARTAN-117 continued his counterstrike across the axial segments of the station, despite the Covenant's significant defenses in their invaded sections, which were entrenched with Plasma Cannons and Stationary Shield Generators. The Covenant also managed to interdict Commander Miranda Keyes, who was attempting to board her warship, the and launch it into the growing orbital combat. However, SPARTAN-117 single-handedly rescued her and continued freeing other parts of the station being besieged by Covenant forces.

SPARTAN-117 eventually located and disarmed the Covenant Bomb, mere moments before it was set to explode. By this point, the Covenant fleet had been reduced to two Assault Carriers, but they had broken through the defensive lines. Commander Keyes and the rest of the fleet prepared to launch an assault on the two vessels, only to be rebuked by Admiral Hood, who insisted that they wait for reinforcement. SPARTAN-117 then requested permission to "give the Covenant back their bomb", which Hood promptly granted. SPARTAN-117 left the station through the airlock, taking the bomb with him and free-falling in Earth orbit.

The Prophet of Regret's flagship descended towards Africa and could not be stopped, but the second carrier remained in Earth orbit. With assistance from UNSC Longsword squadrons, SPARTAN-117 was able to infiltrate the carrier and re-activate the bomb. The Master Chief fled just as the entire vessel exploded. The Master Chief then free-fell onto the UNSC In Amber Clad, and later joined in the First Battle of Mombasa, which was unfolding on the surface.

Ground Battle
Regret's carrier came to a stop above the city of New Mombasa in the East African Protectorate. From there the first Covenant troops to ever set foot on humanity's homeworld engaged in the first land engagement of the First Battle of Earth.

The In Amber clad descended near Mombasa, and deployed three pelicans, one with Spartan-117 onboard, with the intent of infiltrating the Carrier and capturing the Prophet of Regret. However, all of the dropships were shot down by a Covenant Scarab in Old Mombasa. Spartan-117, with the assistance of numerous Marines, made his way through Old Mombasa, to NM 105E, and across the bridge to New Mombasa Sector B, where the Scarab was eventually trapped and destroyed. During the battle's final moments, the Covenant forces started to retreat back to the Carrier. Meanwhile, an ODST force aboard the in orbit, was deployed with the mission to attack the Carrier from above.

Regret's Retreat
Seeing the Carrier was retreating, Commander Keyes ordered Spartan-117 to be extracted back to the In Amber Clad. Moments after this, the Carrier jumped into slipspace while still above the city, with the In Amber Clad following in its wake. The ODSTs were still on their way, and could do nothing but watch as the carrier's slipspace rupture generated a massive shockwave, which severely damaged the city, as well as an EMP, which disabled the ODSTs' drop pods' electronic systems. They were scattered around the city, the ones close to the carrier presumably killed by the slipspace rupture.

Covenant Occupation
Immediately following the slipspace event, a Jiralhanae-led occupation force was inserted into the New Mombasa, a part of the Prophet of Truth's plan to eventually replace the Sangheili with Brutes as the Covenant's primary warrior race. The surviving UNSC and NMPD forces clashed for control of the city. A squad of ODSTs, with the assistance of Marine and NMPD survivors, as well as the city's AI Superintendent, participated in various battles, including the Battle of the ONI Alpha Base. Despite their efforts, the city was eventually lost to the Covenant due to their overwhelming force. After this, the recently-arrived Covenant ships started uncovering the Portal to the Ark, glassing the Mombasa area along with its surroundings.

In the following weeks, the desperate battle for Earth was far from over. The Spartan Blue Team, SPARTAN-104, SPARTAN-058, and SPARTAN-043 partook in numerous battles around the globe, including many orbital zero-gravity operations, a battle at Mount Erebus in the Antartica where they neutralized a Covenant excavation with a HAVOK tactical nuke, as well as an underwater mission off the Yucatan Peninsula. On November 3, they partook in the Battle of Havana in Cuba.

Also on November 3, the Prophet of Truth left High Charity in the Forerunner Dreadnought, destined to arrive at the Sol System on November 8, secretly carrying the stowaway John-117, returning to "finish the fight". The Prophet of Truth's intention was to activate The Ark, fire the Halo rings, and begin what he thought would be the "Great Journey".

On November 17, the Forerunner Dreadnought reached Earth. SPARTAN-117 - the Master Chief, escaped by jumping from the ship and entered Earth's atmosphere, crashing into an East-African jungle.

Turning point
In the morning, the Master Chief was retrieved by Sergeant Major Avery Johnson, along with the Arbiter and a group of marines. The company then fought their way through the Covenant captured territory and were extracted and taken to the Crow's Nest - one of the last UNSC strongholds and bastions in Africa. Here, Commander Miranda Keyes and Lord Hood planned a last-ditch and last-resort effort to cease Truth's activation plan. Shortly after the Chief's arrival, however, the outpost was discovered and quickly attacked by Covenant forces. After the base was taken over, the Marines, with the help of Master Chief destroyed it using a bomb, killing all the Covenant in the base. The Master Chief activated the bomb and was barely able to escape the explosion. Scattered, the UNSC forces then fled the base along the Tsavo Highway and were given orders by Commander Keyes to head to the city of Voi.

Upon reaching Voi, the Humans, with almost all organization collapsing, launched one last desperate plan. With the help of the Master Chief, the human forces destroyed a small section of the defenses around Truth and the artefact, allowing Lord Hood to lead the last reserves of ships in an attempt to destroy it.

Nothing came out of this however, because the human ships did seemingly no damage to Truth's ship, who activated the artifact, creating a large slipspace portal into which most, if not all of the Covenant Loyalist ships on Earth retreated.

At this exact moment, a Flood-controlled ship arrived at Earth and infested the area around the Portal, spreading throughout the city of Voi. Covenant Separatists arrived from their quarantine of Delta Halo to relieve the battered humans and glassed the city of Voi and surrounding countryside, destroying the Flood threat.

Timeline

 * For more detailed information, see the First Battle of Mombasa.

No official timeline has been given, however the events of Halo 2 sum up the basic attack. The UNSC were caught off guard, though assembling a strong prepared response, mirroring the Covenants total surprise that there were humans on Earth at all.

October 20, 2552
 * Lord Hood awards SPARTAN-117, Sergeant Johnson and Jacob Keyes (posthumously) medals for their efforts during the Battle of Installation 04 and subsequent actions. Miranda Keyes received the medal posthumously given to her late father, Captain Keyes. The ceremony takes place on Cairo Station.
 * A Covenant task force of 2 Assault Carriers and 13 s exits Slipspace just beyond the range of the MAC satellites.
 * It is speculated that at this time, the warning sirens heard in the ilovebees storyline begin shortly after this Covenant sighting.
 * Fleet Admiral Harper, in charge of the Earth defense fleet, responds rapidly with an attempt at a counter attack, preparing all available vessels to engage the Covenant. This order is overruled by Lord Hood.
 * The Covenant launch waves of boarding craft toward the orbital defense stations. Several UNSC vessels and stations are destroyed by boarding Covenant forces.
 * The MAC platform Malta, after sending elated communications that they have repelled all Covenant boarders, is annihilated in a cataclysmic explosion. The shockwave of which is felt by the crew of the Cairo station, demonstrating just how large the detonation was. Shortly afterward the Athens MAC platform experiences the same fiery fate.
 * It is deduced that both explosions came from within each of the stations, the Covenant boarding parties had brought with them a bomb, detonated close to the MAC magazine housing causing multiple secondary explosions as the ammunition is cooked-off. As a result all personnel on orbital platforms redouble their efforts.
 * The Cairo MAC platform is saved by the heroic efforts of Spartan-117. single-handedly disarming (with the aid of Cortana who was acting as the platform's AI) and removing the Covenant Bomb from the orbital platform. The Master Chief removes the explosive device by jettisoning it, along with himself, out of a docking bay airlock. He then uses this same bomb to destroy a Covenant Assault Carrier that had just broken through the UNSC's defensive perimeter.
 * During a protracted naval engagement a Covenant Assault Carrier blows through the Malta's debris field and heads straight for Earth. It comes to a stop above the city of New Mombasa in the East African Protectorate.
 * From there the first Covenant troops to ever set foot on humanity's homeworld engage in the first land engagement of the First Battle of Earth.
 * UNSC forces engage the Covenant on the ground and wage a bloody street-by-street war in both Old and New Mombasa.

October 23, 2552
 * After three days of ground battle in the Mombasa area, SPARTAN-117, along with several Marines, are sent to crush the Covenant resistance in the city and infiltrate the Prophet of Regret's Assault Carrier above the city, backed up by an ODST force which would be inserted from orbit.
 * The arduous ground war is ended with the Prophet of Regret's Assault Carrier making a Slipspace jump only hundreds of meters above the city of New Mombasa. His motivations for doing so were, at the time, unknown. The Assault Carrier is followed by the, which, upon arrival begins the Battle of Installation 05.
 * This atmospheric Slipspace jump severely damages the City of New Mombasa. The ODSTs' drop pods are scattered around the city, most of them presumably killed by the slipspace rupture.
 * Immediately following the slipspace event, a Jiralhanae-led occupation force is inserted into the New Mombasa. The surviving UNSC and NMPD forces clash for control of the city. Eventually, the city is occupied and its surroundings glassed by the Covenant, to uncover the Ark Portal.

Late October and early November
 * The Spartan Blue Team gets deployed to defend Earth during In Amber Clad's disappearance. They participate in numerous combat missions around the world.
 * In November 3, SPARTAN-104, SPARTAN-058, and SPARTAN-043 partake in the Battle of Havana. Shortly thereafter, they depart for Onyx.
 * In November 8, the Forerunner Dreadnought arrives in the Sol system and proceeds to Earth at near-relativistic speeds. The Second Battle of Earth begins.

Additional Notes And Theories
UNSC High Command found it puzzling, to say the least, that a Covenant fleet of such small size, carrying a Prophet, would be their first engagement in the defense of Earth. The fleet that glassed Reach was fifty times the size of this new threat. To attack such a heavily prized and defended world, a fleet of greater size than the fleet at Reach would be required.

Not only this, the fact that only one city on Earth was attacked left UNSC strategists baffled. At the bare minimum the invading force would have to attack and occupy multiple areas, providing at least some strategic benefit, synchronously. Given the Covenant's tactical history it seemed unlikely that they would be prone to overconfidence.

Compared to the invasion force at Reach the two simply did not match up. The Covenant force at Reach was not only massive in numbers, it was knowledgeable of the terrain. The invasion force at Earth was small and displayed confusion (not an attribute the Covenant are known for).

The fleet that attacked Reach even took their time glassing the surface prior to sending in ground forces. Again the fleet that attacked Earth did almost the exact opposite, rushing to get to the surface. These observations could suggest that this Covenant fleet was not an invasion fleet at all but rather a planetary reconnaissance, search, and dig team.

Although capable of combating a small colony and/or aggressive native lifeforms, the expeditionary fleet lacked the strength in force or numbers for a full-scale invasion attempt. Speculation arose that, following the Covenant's discovery of Delta Halo, they found some form of Forerunner technology that led them to the location of a Shield World.

Another possible scenario explaining the events, but highly inadmissible due to lack of timeline during the events of Halo 2, is that after the seizure of 343 Guilty Spark, and subsequent interrogation, the location of the end of their pilgrimage was located. Even if the specific name "Earth" was used by the monitor, it would have raised no caution in the Covenant ranks; to their knowledge, the location of planet Earth was unknown to humans. It could be hypothesized that due to the assuming nature of Installation Monitor's, Guilty Spark would have made no mention of Humans living there unless specifically asked.

There is also the suggestion that the Covenant were following a signal which emanated from the Forerunner Deep-Space Artifact brought to Earth aboard the Apocalypso when it was deactivated by Jersey Morelli. The burst of EMP, Slipspace, and Realspace signals could be what drew the Covenant to Earth. This would make sense if Regret's fleet came to Earth looking to recover the artifact and knew nothing about the planet itself. While it had been previously revealed that the Covenant knew the location of Earth, it is not known what value they assigned to it. To them, it may have simply been the location of the artifact in Chawla Base, not the human home world.

The Covenant's extensive knowledge of the MAC stations orbiting Earth might be seen as evidence that the Covenant knew the planet was at least occupied by human forces. However, Covenant forces had already encountered such orbital "Super" MAC guns before, over Reach. Recognizing the serious danger these platforms represented the fleet halted just beyond their firing range to commence boarding and sabotage actions using smaller craft.

Although losses weighed more heavily on the Humans than the Covenant, the UNSC nevertheless fought a successful holding action at New Mombasa. However, it is probable that UNSC High Command deliberately neglected to tell the medium and lower ranks that the Covenant task force was really but a vanguard of a much larger invasion fleet that would surely be imminent now.

UNSC

 * ODA-143 Malta Station
 * ODA-142 Cairo Station
 * ODA-144 Athens Station

Covenant

 * Pious Inquisitor
 * Regret's Carrier (Possibly Infinite Sacrifice)

UNSC Marine Corps

 * 7th ODST Battalion (Unknown Regiment)
 * 1st Platoon (Unknown Company and Regiment)
 * 405th
 * A Company
 * 17th Marine Regiment
 * 77th Marine Regiment

UNSC Navy

 * Second Fleet
 * Seventh Fleet
 * Sixteenth Fleet
 * 6th Battle Group

UNSC

 * Fleet Admiral Sir Terrence Hood
 * Fleet Admiral Harper
 * Lieutenant Commander Miranda Keyes
 * Commander Richard Lash
 * Lieutenant Commander Julian Waters
 * Lieutenant Commander Xaing Cho
 * Lieutenant Bethany Durruno
 * Lieutenant Joe Yang
 * Lieutenant Junior Grade SPARTAN Frederic-104
 * Master Chief Petty Officer SPARTAN John-117
 * Sergeant Major Avery Junior Johnson
 * Gunnery Sergeant Pete Stacker
 * Petty Officer Second Class SPARTAN Linda-058
 * Petty Officer Second Class SPARTAN Will-043
 * Staff Sergeant Marcus Banks
 * Corporal Perez
 * Private McKenzie
 * Unnamed Marine Officer
 * Unnamed UNSC Navy Captain
 * Captain Veronica "Dare"
 * Gunnery Sergeant Edward Buck
 * Corporal Taylor Miles
 * Lance Corporal Kojo Agu
 * Lance Corporal "The Rookie"
 * Private First Class Michael Crespo

Covenant

 * High Prophet of Regret
 * High Prophet of Truth