Timeline of the Human-Covenant War

This is a timeline of the events slightly before, during, and slightly after the Human-Covenant War. The war began in early 2525, with the First Battle of Harvest, though the broader UNSC and UEG wouldn't become true and active participants until near the end of the year. The war would end in 2552. For the Covenant, the war marked the beginning of and took place during the 9th Age of Reclamation.

Concurrently with the Human-Covenant War was the end stages of the Insurrection, the creation and subsequent raids by the Banished, the Raid on the Threshold gas mine, and the entirety of the Great Schism.

2524 (Pre-war)

 * A damaged human civilian freighter, Horn of Plenty, suffers a slipspace drive malfunction from Harvest to Madrigal, forcing the unmanned freighter to exit back into normal space. A Covenant vessel, Minor Transgression, comes into contact after hours of the freighter's isolation. The Covenant vessel targets the freighter, and a Jackal boarding crew enter.

2525

 * The first conflict between humanity and the Covenant takes place prior to the outbreak of the war. Humanity attempts to gain a truce between the races through a pictogram of trade and peace between the Covenant and humanity, but to no avail. (Pre-War)


 * The Covenant launch a full-scale assault on Harvest, glassing the planet. Afterward, the Minister of Fortitude, Vice-Minister of Tranquility, and the Philologist become the High Prophets of Truth, Regret, and Mercy, and declare war on humanity.


 * The Human-Covenant war begins.


 * Shortly after the attack on Harvest, the colonies of Green Hills and Second Base are glassed.


 * The Battle of Chi Ceti takes place, marking the first real ship-to-ship engagement between humanity and the Covenant. It is also the first uncontested human victory.


 * The Battle of Alpha Corvi II takes place; the Covenant launch a major assault on the city of Jamshid. While the UNSC Navy engages the Covenant in orbit, the Spartan Blue Team is deployed to discreetly aid the UNSC Marine Corps ahead of a major counterattack. An alliance with the United Rebel Front prevents the Covenant's acquisition of Forerunner artifacts, but the UNSC is unable to stop the invasion. The UNSC ultimately retreats, and the entire rebel force is annihilated when they are refused evacuation.

2526

 * Battle of Harvest. The UNSC and Covenant meet in a fleet-action for the first time; though only one Covenant ship faces a UNSC battle-group of 40, it is a rare, exceptionally powerful super-destroyer. The battle is a high-priced victory for the UNSC, costing the UNSC 13 ships—about one-third of the battlegroup that was assembled to face the threat. The Covenant would return to Harvest later in the year, and the battle for the planet and its surrounding systems, dubbed by the UNSC as the Harvest Campaign, would last for the next five years.
 * Battle of Circinius IV. The Covenant attacked the UNSC Corbulo Academy of Military Science on Circinius IV, catching the cadets there off guard and sparking a massive ground battle for control of the academy. The Spartan Blue Team was deployed to fight the Covenant soldiers and to evacuate the trainees who were forced to engage the enemy in close-quarters combat. The battle resulted in the near-complete extermination of the planet's population, including those of the Corbulo Academy save for the survivors of Hastati Squad.
 * Battle of Alpha Aurigae. Another ship-to-ship battle, where the UNSC outnumber the Covenant almost 10–1, but lost a third of the ships. This was one of the rare naval "victories" for the UNSC, won because of their numerical superiority over the Covenant in that battle.
 * Battle of Mesra. The Covenant invade Mesra in the Qusdar system, occupying the planet and seizing the planet's many mining facilities in order to seize the planet's plentiful resources. To ensure the success of the operation, they do not commit to the immediate glassing of the colony. In response, Admiral Cole deploys Blue Team to spearhead the UNSC's attempt to retake the planet, negotiating a truce with the Militia of Mesra in order to wipe out the invaders. Blue Team succeeds in destroying the mines before the Covenant can exploit their resources.

2528

 * Battle of XI Boötis A, the UNSC fleet of 70 warships destroy 8 enemy vessels, losing 30 of their own in the process.
 * Madrigal is glassed by The Covenant.

2528 or 2529

 * Battle of Hat Yai.

2530

 * The Covenant glasses the UNSC colony world of Eridanus II
 * Battle of Groombridge-1830, 11 UNSC Destroyers are lost in attempt to defeat a Covenant fleet of 3 warships; the battle ends in a costly victory in which the UNSC learns from the interrogation of a Covenant prisoner of the reason for their intended extermination.

2531

 * The UNSC finally manages to retake Harvest, ending the five-year long Harvest Campaign in a UNSC victory.
 * Battle of Arcadia, UNSC victory; the humans successfully repel the Covenant after a costly holding action.
 * Battle of the Etran Harborage, UNSC victory; human forces eliminate a Forerunner fleet reactivated by the Covenant; the is drifting through unknown space and eventually declared lost with all hands.
 * Kurt-051 is kidnapped by Section III of ONI to train the classified SPARTAN-IIIs, in a need for more supersoldiers to fight the Covenant.

2532

 * Battle of Vodin, Covenant attack the UNSC colony, but the planet is not destroyed; Spartan-II soldier Randall-037 is listed as MIA.

2535

 * In an effort to better protect the remaining human worlds, the UNSC implements the Cole Protocol.
 * The Covenant destroys the UNSC colony world of Jericho VII in the Battle of Jericho VII.
 * Battle of Charybdis IX.
 * Battle of the Rubble.
 * 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 and rarely without the Spartans' assistance. In space combat, the humans are losing at a precipitous rate, and one by one, the colonies fall.

2537

 * Discovery of Covenant Manufacturing Plant K7-49 at the Battle of New Harmony.
 * Battle of New Constantinople, UNSC victory.
 * Battle of Leonis Minoris, Covenant destroys two of the three colonies in the Leonis Minoris system.
 * Siege of the Atlas Moons was a rare victory for the UNSC, as victories in space-based fighting were uncommon for the UNSC Fleet.
 * Operation: PROMETHEUS: UNSC victory. SPARTAN-III Alpha Company is killed by Covenant forces.

2539

 * Battle of Kholo, Covenant forces glass the colony of Kholo.

2542

 * Battle for Alluvion, Covenant victory, Alluvion is glassed.

2543

 * On March 6 the Battle of 18 Scorpii takes place. In the battle prior-unknown Independent/Insurrectionist human forces assist three UNSC destroyers in defeating a Covenant CPV destroyer.
 * Vice Admiral Preston J. Cole is presumed to have made his last stand at the Battle of Psi Serpentis on April 18. Over 300 Covenant ships destroyed in the battle. As of this time, it is humanity's greatest single victory in the war.

2544

 * Battle of Miridem, the SPARTAN-II Sheila-065 is killed while protecting Dr. Catherine Halsey on Miridem. Halsey is subsequently captured by Covenant forces, and is placed on board a Covenant assault carrier in the Third Fleet of Glorious Consequence.
 * Operation: WARM BLANKET, following Halsey's capture by the Covenant, the Office of Naval Intelligence initiates an operation to rescue her with the assistance of five SPARTAN-IIs. The operation is a success, and Halsey is rescued, at the cost of two of the Spartans.

2545

 * Battle of Draco III. Covenant kill all UNSC ground forces and captured thousands of civilians. Later a SPARTAN squad arrive and kill all Covenant forces only to find that the civilians were killed by ravenous, raging Grunts and Jackals.
 * Operation: TORPEDO: UNSC victory. All participating SPARTAN IIIs, with the exception of Tom-B292 and Lucy-B091 of SPARTAN-III Beta Company are killed by Covenant forces.
 * Battle of Actium: Covenant victory. The 53rd Armored Division is wiped out in a nuclear attack aimed at halting the Covenant offensive on the UNSC colony of Actium; Although casualties are high, the Covenant ultimately glass the planet.

2546

 * Sargasso is attacked by the Covenant. This engagement marks the first appearance of the Type-46 Infantry Support Vehicle.
 * Battle of New Llanelli: Covenant victory, New Llanelli is glassed.

2547

 * The UNSC colony of Skopje is destroyed by the Covenant.

2548

 * Battle of Meridian, UNSC victory; Covenant armada is repelled.

2549

 * Siege of Paris IV, Covenant victory.
 * Fall of Arcadia, Covenant victory, Arcadia is glassed.

2551

 * Battle of Meridian resumes, Covenant victory; The Covenant glass the colony as the UNSC retreats, recovering a Forerunner Luminary that contains to the coordinates to "Erde-Tyrene". Unbeknownst to them, it is the human homeworld Earth.

April

 * Battle of Fumirole. Thom-A293 is killed and Catherine-B320 loses her arm.

July

 * Battle of Sigma Octanus IV. The single greatest UNSC victory since Harvest. However, the Covenant gain what they seek: the location of Installation 04. They also discover the human presence on Reach.


 * The Covenant discover Reach, and send in an advance invasion force, beginning the prolonged Battle of Reach.


 * Battle of Criterion. Gabriel Thorne single-handedly saved his entire platoon.

August

 * Battle of Tribute. Along with other colonies in the Epsilon Eridani System, Tribute is invaded by Covenant forces. The colony is not glassed instantly, but remains under siege by Covenant forces for some time.


 * Raid on Verge. A Covenant Beacon transmitting helium-3 for ships blockading Tribute is destroyed by Team Black.


 * Battle of Line Installation 1-4. A UNSC ship on a covert mission, as well as a Covenant Assault Carrier, crash on a remote moon with a Forerunner relic. In the ensuing engagement, the surviving UNSC forces side with the Covenant against the installation's defense systems.


 * The Fall of Reach ends. On August 30, 314 Covenant ships destroy over 130 UNSC ships and 20 ODPs for the loss of at least two-thirds of their fleet. It is a major Covenant victory: Reach is the last major stronghold before Sol. The UNSC Pillar of Autumn escapes.

September



 * Battle of New Jerusalem. Following an attack on the UNSC colony of New Jerusalem, the 26th Marine Expeditionary Force is sent to reinforce the UNSC forces already present. The colony is eventually lost to the Covenant and the survivors fall back to Earth.


 * Raid on Mount Haven
 * Battle of Installation 04. The Pillar of Autumn engages the Covenant Fleet of Particular Justice at Halo Installation 04. After four days, the battle degenerates into a four-way melee as the Flood organisms are released and Forerunner constructs, Sentinels seek to contain the outbreak. The crew of the Pillar of Autumn are instrumental in preventing the Flood from escaping and the installation from firing by destroying the installation. There are only a handful of survivors.


 * Skirmish over Threshold. UNSC survivors from the Battle of Installation 04 rally in orbit over Threshold. Using their limited resources to the fullest they manage to capture the Covenant vessel Ascendant Justice and use it to escape.


 * Raid of Reach. John-117 and some of the survivors of the Battle of Installation 04 raid Reach to rescue a SPARTAN-II team trapped on Reach by a Covenant fleet. They rescue the Spartan squad leaving a great deal of damage to the Covenant fleet ships and the ground forces.


 * Massacre at Eridanus Secundus. It was a minor event in the Human-Covenant War that ultimately resulted in the destruction Eridanus rebels by the Covenant. It is most notable for the involvement of the Gettysburg-Ascendant Justice and Dr. Halsey's kidnapping of Kelly-087.


 * Operation: FIRST STRIKE. Five SPARTAN-II super soldiers route and destroy a fleet of 500 Covenant warships preparing to jump to Earth. This is accomplished through the destruction of the massive mobile space station Unyielding Hierophant. This is the single greatest victory, for the humans during the entire war and the single greatest loss to the Covenant.

October

 * Battle for Earth. High Prophet of Regret's fleet of 15 Covenant ships assault Earth, defended by the UNSC Home Fleet and 300 ODPs. Regret's fleet were not expecting the heavy human presence, as well as their new orbital MAC defenses, and is completely destroyed save for the Solemn Penance- the High Prophet of Regret's personal assault carrier, and the Pious Inquisitor and at least 2 other battlecruisers. However, fleets of Covenant capital ships appears soon after, prolonging the battle.

November

 * Battle of Installation 05. The Solemn Penance arrives at Installation 05, being pursued by four small UNSC warships. Only one, the, arrives in time to participate in the battle.
 * The Prophet of Regret is assassinated by John-117.
 * The Great Schism begins. Covenant forces are thoroughly divided between the Sangheili and the Jiralhanae. Every race in the Covenant takes sides.
 * The Prophet of Mercy is killed by a Flood Pod infector while the Prophet of Truth leads the remaining loyalist forces to Earth.
 * An alliance is formed between human forces led by Sergeant Major Avery Johnson and Sangheili-led forces commanded by Arbiter Thel 'Vadam to stop Chieftain of the Jiralhanae Tartarus from firing the ring.
 * Once again, the installation is prevented from firing and the Flood appears to take control of the installation and High Charity.
 * Due to the premature deactivation of Installation 05, the entire Halo Array is put into standby mode to be fired from the Ark.
 * Onyx Conflict. The destruction of Installation 04 wakes dormant Forerunner installations, including the Sentinels on Onyx which then threaten the UNSC base there. The SPARTAN-IIs of Blue Team fight their way off of Earth and commandeer a, the Bloodied Spirit, to relieve Onyx. Covenant and UNSC ships converge on Onyx but ultimately all are destroyed except for the . UNSC survivors retreat within the Onyx shield world Sarcophagus.
 * The destruction of Joyous Exultation. A Sangheili-led Covenant fleet led by Imperial Admiral Xytan 'Jar Wattinree assembles to besiege the Covenant forces on the colony world of Joyous Exultation. During this, the Covenant accidentally trigger a captured NOVA bomb recovered from Reach, annihilating the fleet, the entire colony and shattering its moon Malhiem.
 * The Battle for Earth continues. The Covenant, led by the Prophet of Truth, arrive at Earth in force, to reinforce the Covenant forces already present. During the following week, Marines, with help of the Sangheili, pushes back the Covenant invaders who retreat through the Portal at Voi to the Ark outside of the galaxy.

December

 * Battle of Installation 00.
 * Amost all Covenant vessels save for at least the Gathering of Praise are destroyed over the Ark by the Sangheili Fleet of Retribution.
 * 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.
 * The Human-Covenant war ends.
 * The flood controlled High Charity is destroyed by the Master Chief after he blasts the city's main reactors causing them to go critical.
 * Raid on Installation 08.
 * Thel 'Vadam, John-117, and Johnson battle to the control room that's on Installation 08. Guilty Spark runs rampant, killing Johnson before apparently being destroyed. Installation 08’s Sentinels turned on John-117 and Thel 'Vadam. The unfinished Installation 08 is activated, severely damaging the Ark and destroying the entire Flood infestation including the Gravemind. These final events ended the Human-Covenant War. However, the is torn in half while entering the portal home, sending 'Vadam to Earth, but leaving John and Cortana lost in space.
 * The Arbiter returns to Earth in the front half of Forward Unto Dawn, crashing into the Indian Ocean. He is safely cut out of the wreckage by UNSC forces. John is left missing in action.
 * Operation: SUNSPEAR
 * Having received word that the Covenant was in the Sol system, Spartan-II Gray Team enacted a secret operation designed to strike hard at the Sangheili in hopes of buying the remnants of humanity some time.
 * Due to a damaged deep-space communications array, Gray Team failed to receive the message that the war was over and their mission was no longer necessary.
 * Just days after the war officially ended, Gray Team destroyed the Sangheili colony world of Glyke with a NOVA bomb, killing billions of Sangheili.
 * Their ship critically damaged in the blast, Gray Team evacuated in their lifeboat and remained adrift in Glyke's remains in cryo chambers.

February

 * Fleet Admiral Hood meets with Arbiter Thel 'Vadam on Sanghelios. They agree to a ceasefire between humanity and the Sangheili loyal to Vadam.

March

 * While the fighting finished in December and the ceasefire was ratified in February, and the formal end of war ceremony did not take place until March. The UNSC erect a monument on a hillside near the Ark's gateway to commemorate those who died during the war, particularly during the Battle on Installation 00. Two of the most prominent figures listed on the memorial are John-117 and Dr. Catherine Halsey, though both remain alive. Thel 'Vadam and his retinue depart for Sanghelios.