A timeline of all major events in the Halo universe from the time of the Forerunners through the rule of the Created.
The Great Schism was a conflict between the forces loyal to the Covenant, led mostly by the Jiralhanae, and the Sangheili, beginning on November 3rd, 2552 and continuing off and on until the Rule of the Created in 2558.
At the start of the Covenant in 851 BCE, a group of Sangheili who did not agree with the peace being formed with the San'Shyuum, formed around their leader Ussa 'Xellus and escaped to a previously unknown Forerunner construct known as Shield World 0673.
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 Blooding Years is the Sangheili term for the civil war that raged for five years on Sanghelios and throughout Sangheili-occupied territories following the end of the Human-Covenant War and disappearance of the San’Shyuum.
The Siege at Kolaar was an attack on Arbiter Thel 'Vadam and his forces by Avu Med 'Telcam and the Servants of the Abiding Truth in the first major conflict of the Sangheili civil war.
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 Attack on Rahnelo was an unprovoked attack by the San'Shyuum Prelate Tem'Bhetek, directed by the former Covenant Minister of Preparation Boru'a'Neem, on the Sangheili colony world of Rahnelo towards the end of 2553.
The Ambush at Duraan was the second part of the prelate Tem'Bhetek's plan to lure in the Shadow of Intent, capture the ship, and kill Rtas 'Vadum.
The Battle of the Prototype Halo Installation was a conflict between Tem'Bhetek, the former Covenant Minister of Preparation Boru'a'Neem, and the Shadow of Intent crew including Rtas 'Vadum and Tul 'Juran.
Operation: RETRIBUTION was an Office of Naval Intelligence mission headed by operative Veta Lopis and her Ferret team to investigate the murder of Vice Admiral Graselyn Tuwa and the kidnapping of her family members on December 6th, 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.
The Return to Installation 00 was an Office of Naval Intelligence mission undertaken by the UNSC Rubicon to return to the Ark following the Battle of Installation 00 and investigate the status of the facility in August 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.
The Invasion of Earth was an attempt by the monitor of Installation 00 to harvest the Earth for resources to repair the Ark when the Portal at Voi was reopened in March of 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 Sedra City Mall Bombing was a terrorist attack on the human colony world of Sedra in the Orrichon system by an unknown Sangheili terrorist organization in February 2556.
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 Mission to Cleyell was a UNSC mission to the colony world of Cleyell, which had recently been glassed by a fringe group of Covenant remnants sometime in 2556.
Sometime in January 2557, Rion Forge, a post-war salvager, and her ship the Ace of Spades, discover the location of what was left of the Etran Harborage after the destruction of the shield world during the events of the Battle of the Etran Harborage in 2531.
Following discovery of the last known location of the UNSC Spirit of Fire from the Battle of the Etran Harborage, the Office of Naval Intelligence sent the UNSC Taurokado to investigate the system for any information regarding the whereabouts of the lost UNSC warship.
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 Raid on Ivanoff Station was an attack by the Ur-Didact and his ship Mantle's Approach on the Office of Naval Intelligence research facility Ivanoff Station nearby Halo Installation 03 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 Mission to Installation 03 was a UNSC operation to investigate the loss of contact with a science outpost and Spartan-II Black Team on Gamma Halo immediately following the New Phoenix Incident in July 2557.
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 Mission to Mount Kilimanjaro was a trek undertaken by 343 Guilty Spark, Rion Forge, and the crew of the Ace of Spades to find the Librarian and, in the case of Spark, gain access to the Domain in September 2557.
