A timeline of all major events in the Halo universe from the time of the Forerunners through the rule of the Created.
The Spartan II program, led by Dr. Catherine Halsey, was a plan by the Office of Naval Intelligence to use children with superior genetic traits to create a group of super-soldiers in order to put an end to the ongoing Insurrection in the outer colonies.
On their first mission as fully augmented Spartan-IIs, Blue Team, consisting of John-117, Samuel-034, Linda-058, Kelly-087, and Fred-104, infiltrate Eridanus Secundus, a hidden United Rebel Front base located in an asteroid field, and capture Colonel Watts.
The Battle of Chi Ceti was a battle between the UNSC Commonwealth and the Covenant vessel Unrelenting in the Chi Ceti system on November 27th, 2525.
The Battle of Alpha Corvi II was a battle between the UNSC and the Covenant forces in the Alpha Corvi system on December 3rd, 2525.
Operation: SILENT STORM was a UNSC operation to use EVA tactics to infiltrate Covenant vessels and either capture or destroy them from within early in the Human-Covenant War in March and April 2526.
The Battle of Circinius IV was a Covenant attack on the planet Circinius IV and Corbulo Military Academy located on the planet.
The Battle of Mesra was a Covenant attack on the human outer colony world of Mesra in late May to early June 2526.
The Battle of Netherop was a conflict between UNSC forces led by Spartan-II Blue Team and Covenant forces on the uninhabited hothouse world in June 2526.
The Battle for Arcadia was a battle for the colony Arcadia in the Procyon system, which occurred in the immediate aftermath of the Harvest Campaign.
The Battle of the Etran Harborage was a battle between the UNSC Spirit of Fire and Covenant forces lead by Arbiter Ripa 'Moramee on Shield World 0459, also known as the Etran Harborage.
Operation: SMOKING ACES was a raid by Spartan-II Blue Team on an Insurrection stronghold in the 111 Tauri system.
Spartan-III Alpha company was the first of three Spartan-III companies to be recruited, trained, and put into service.
The Battle of Jericho VII was a three-day naval and ground battle pitting the UNSC versus the Covenant forces in the Lambda Serpentis system.
The Battle of the Rubble was a battle that took place in the 23 Librae system on a grouping of Lagrangian asteroids trailing Hesiod, a gas giant in the system, some time around 2535.
The Battle of Metisette occurred in the immediate aftermath of the Battle of the Rubble in 2535, taking place on Metisette, the nearby moon of the gas giant Hesiod.
The Battle of New Harmony was an assault on the colony New Harmony by Covenant forces in early 2537.
The Battle of New Constantinople was a large conflict between UNSC and Covenant forces that took place some time in early 2537 on the colony of New Constantinople.
Operation: PROMETHEUS was an assault on a Covenant shipyard located on and around asteroid K7-49 by Spartan-III Alpha Company.
Spartan-III Beta company was the second of three Spartan-III companies to be recruited, trained, and put into service.
Operation: GREY VEIL was an Office of Naval Intelligence mission to assassinate a Covenant Prophet on the planet Heian sometime in 2541.
Operation: WARM BLANKET was an operation to recover Doctor Halsey from the Covenant after her capture during the Battle of Miridem in 2544.
Operation: IRON FIST was a military operation on the colony of Miridem after the Battle of Miridem in 2544 and prior to the colony's glassing.
Spartan-III Gamma Company was the last of three Spartan-III companies to be recruited, trained, and put into service.
Operation: TORPEDO was a mission by Spartan-III Beta Company to infiltrate and destroy a Covenant refinery on Pegasi Delta, the moon of 51 Pegasi B in the 51 Pegasi system.
In an effort to boost morale, the Office of Naval Intelligence made public the existence of the Spartan-II program and the accomplishments of the Spartan-IIs in May, 2547.
The Battle of Fumirole was a conflict between Covenant and UNSC forces on the colony Fumirole, April 22nd, 2552.
The Battle of New Jerusalem was a Covenant attack on the colony of New Jerusalem in the Cygnus system sometime in July or August 2552.
Operation: RED FLAG was a planned operation by both the Office of Naval Intelligence and the UNSC to use Spartans to capture a Covenant ship, use it to penetrate into Covenant space, and capture a Hierarch, with the intent of using the Prophet to broker a cease-fire.
The Battle of Sigma Octanus IV was a large-scale space and ground battle between UNSC and Covenant forces in the Sigma Octanus system in July 2552.
The Fall of Reach was possibly the largest battle during the Human-Covenant War, taking place in the Epsilon Eridani system, in orbit and on the ground of Reach, humanity's largest military stronghold.
The Raid on Verge was a covert mission undertaken by Spartan-II Black Team to infiltrate and destroy a Covenant mining and refinery operation on the recently invaded former colony of Verge towards the end of July 2552.
The Battle of Line Installation 1-4 was a conflict on Line Installation 1-4, a Forerunner defensive facility that was part of the Jat-Krula, the Forerunner's version of the Maginot Line during the Forerunner-Flood war in August 2552.
The Battle of Tribute was a large-scale invasion of the colony world Tribute in the Epsilon Eridani system by Covenant forces during and after the Fall of Reach in 2552.
The Massacre at Eridanus Secundus was a Covenant attack on a rebel facility within a series of asteroids in the Eridanus system in late 2552.
Operation: FIRST STRIKE was a mission undertaken by John-117 and several other Spartan-IIs to infiltrate and destroy the Covenant space station Unyielding Hierophant and associated armada of over 500 warships in the Tau Ceti system prior to the Covenant's invasion of Earth.
The Battle of Installation 04 was an engagement between the UNSC Pillar of Autumn and the Covenant Fleet of Particular Justice on and around the Forerunner megastructure known as Installation 04, or Alpha Halo, in the Soell system.
The Battle for Earth was a large-scale space, air, and ground battle between the invading Covenant forces and the UNSC Home Fleet on and around Earth at the end of 2552.
The Onyx Conflict was a major engagement between UNSC, Covenant, and Forerunner forces on and around the planet of Onyx in the Zeta Doradus system in October and November 2552.
The Battle of Installation 05 was an engagement between the Covenant forces, including those that fled the Battle for Earth, High Charity, and the Second Fleet of Homogeneous Clarity, and the UNSC-allied forces, including the UNSC In Amber Clad led by Miranda Keyes, and the Fleet of Retribution led by the Arbiter Thel 'Vadam.
The Battle of Installation 00 was a major conflict between the forces stationed aboard the UNSC Forward Unto Dawn and Arbiter Thel 'Vadam's Fleet of Retribution, and the Covenant fleet loyal to the Prophet of Truth.
Operation: SUNSPEAR was a mission to infiltrate Covenant space and destroy a major population center as an act of revenge for the Fall of Reach at the end of 2552.
The Spartan-IV program was the third successful Spartan training program and the first since the end of the Human-Covenant War.
The Raid on UNSC Infinity was an attempted infiltration and commandeering of the UNSC Infinity by insurrectionist forces calling themselves the New Colonial Alliance in January 2553.
The Skirmish on Pious Inquisitor was a small battle that took place between ONI intel unit Kilo-Five and Kig-Yar pirates on the CCS-class battlecruiser Pious Inquisitor in the Shaps system in April 2553.
Operation: JOVIAN WHISTLE was an operation executed by the UNSC 717th Xeno-Materials Exploitation Battalion to recover a Forerunner ancilla on the human colony world of Gao in the Cordoba system in the early summer 2553.
The Draco III Rebellion was an insurrectionist rebellion led by United Rebel Front leader Captain Ingridson in the city of New Albany on the colony world of Draco III in January 2554.
The Spartan-IV program was the third successful Spartan training program and the first since the end of the Human-Covenant War.
The Battle of Draetheus V was an attack by former Covenant forces under the command of Sangheili Zealot Merg Vol on the colony world of Draetheus V and its moon X50 sometime in 2554.
The Spartan Training Station Bombing was a terrorist attack on an orbital Spartan training facility by the United Rebel Front on March 29th, 2554.
Operation: FAR STORM was a joint UNSC and Swords of Sanghelios mission to reactivate the Portal at Voi and travel back to Installation 00 after discovering the Halo array was counting down to activation in March 2555.
Operation: COALPEPPER was an ONI and Spartan operation to rescue Sadie Endesha and the Huragok Quick to Adjust to whom she was assigned from the United Rebel Front on the moon of Talitsa in the Sverdlovsk system in August 2555.
The Mission to Alpha Shard was a joint ONI and Sedran Colonial Guard mission to secure and eliminate the source of the bio-weapon used in the Sedra City Mall Bombing in February 2556.
The Battle of Requiem was a conflict between former Covenant forces under the command of Jul 'Mdama, UNSC forces from the UNSC Infinity and Forward unto Dawn, and Promethean forces under command of the Ur-Didact on Forerunner Shield World 0001, also known as Requiem, in July 2557.
The Battle of Installation 03 was a battle between the UNSC and Covenant remnant forces under command of Jul 'Mdama on Gamma Halo during and immediately following the New Phoenix Incident in July 2557.
The New Phoenix Incident was an attack by the Ur-Didact on the Earth city of New Phoenix on July 25th, 2557 using the Composer that he had acquired from Ivanoff Station the day prior.
The Battle of New Phoenix was a military engagement between the UNSC and Covenant remnant forces under command of Jul 'Mdama in the city of New Phoenix on Earth, immediately after the New Phoenix Incident and the Battle of Installation 03 in July 2557.
The Requiem Campaign was a UNSC mission to return to Requiem, and take control of the shield world away from Jul 'Mdama and his Covenant remnants in February 2558, six months after the Battle of Requiem.
The Battle of Ealen IV was an attack on peace negotiations between the Sangheili and Jiralhanae on Ealen IV in the Ealen system in March 2558.
The Ambush at Oth Lodon was an attempt by the New Colonial Alliance to destroy the UNSC Infinity and kill Admiral Hood after the failed assassination attempt at Ealen IV days earlier.
The Raid on the Biko Peace Talks was an attempted terrorist attack on peace talks between the Unified Earth Government and Sangheili on the colony world of Biko in March 2558.
Operation: WHISTLE STOP was a UNSC and ONI mission to recover a potential bio-weapon from a group of Sangheili and Kig-Yar pirates on the planet Ven-III in May 2558.
The Battle of Oban was a conflict between the UNSC and Covenant forces under command of Jul 'Mdama on the colony world of Oban in July 2558.
The Battle of Aktis IV was a conflict between the UNSC forces aboard the Infinity and the Covenant forces under command of Jul 'Mdama on the planet of Aktis IV in July 2558.
The Carrow Conflict was a conflict between human, Sangheili, and Jiralhanae forces in the Joint Occupation Zone on the planet of Carrow in September 2558.
Operation: ATHENA was a covert UNSC mission to infiltrate the Song of Retribution, and retrieve the Janus Key from Jul 'Mdama and his Covenant remnant forces in September 2558.
The Battle of Kamchatka was a battle between Covenant remnant forces under the leadership of Jul 'Mdama, local Promethean forces under control of Cortana, and the UNSC in the form of Spartan-IV Fireteam Osiris on the planet of Kamchatka in October 2558.
Operation: BIRD IN HAND was a UNSC mission carried out by Spartan-II Blue Team to infiltrate and recover the Office of Naval Intelligence research vessel Argent Moon on October 23rd, 2558.
The Raising of the Guardians was a series of events involving the awakening and unearthing of Forerunner ships known as Guardians by Cortana in late October 2558.
The Battle of Genesis was an engagement between the UNSC, Promethean forces under command of Cortana, and the remains of Jul 'Mdama's Covenant forces on the artificial Forerunner installation known as Genesis in October 2558.
The Second Battle of Meridian was a conflict between the colonists of Meridian funded by the Liang-Dortmund Corporation, the UNSC, and Prometheans under control of Cortana on October 25th, 2558.
The Battle of Cassidy III was a conflict between Spartan-IV fireteam Alpha-Nine, allied with United Rebel Front forces on Cassidy III, and the Promethean forces under command of the Created late in 2558.
The Second Ark Conflict was a battle between the UNSC forces aboard the Spirit of Fire and the Banished forces under command of Atriox on Installation 00 in 2559.
The Installation 07 Conflict was a battle between UNSC forces led by John-117 and the Banished on Zeta Halo between December 12th, 2559 and May 31st, 2560.
