First Battle of Earth

The First Battle of Earth was a considerably massive but brief engagement between the Covenant and UNSC forces. Covenant and United Nations Space Command ground, air and space engagement occured on the planet Earth, inside the Sol System on October 20, 2552.

Introduction
The Covenant had 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 navigations 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 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 Heirophant'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 socio 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
The Covenant Fleet was detected while en route near Io, one of the moons of Jupiter. Probes were sent to investigate, but shortly afterwards, 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 began to get ready 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 afterwards 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. 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, diffusion of 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 diffused 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 Battle of New Mombasa, which was unfolding on the surface.

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.


 * 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.
 * Note: 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 afterwords 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 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. It is confirmed that this same bomb was used to destroy a Covenant Assault Carrier that had just broken through the UNSC's defensive perimeter.
 * After 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 East African Protectorate of New Mombasa.
 * 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.
 * This arduous ground war 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 completely obliterates the City of New Mombasa.
 * The remaining Covenant vessels are presumed destroyed.

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 comparable or much greater size of 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.

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 Mombassa. 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

UNSC

 * Fleet Admiral Sir Terrence Hood
 * Fleet Admiral Harper
 * Commander Miranda Keyes
 * Commander Richard Lash
 * Lieutenant Commander Julian Waters
 * Lieutenant Commander Xaing Cho
 * Major Easley
 * Lieutenant Bethany Durruno
 * Lieutenant Joe Yang
 * Lieutenant Junior Grade SPARTAN Frederic-104
 * Master Chief Petty Officer SPARTAN John-117
 * Sergeant Major A.J. 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

Covenant

 * High Prophet of Regret

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