Created uprising

In October 2558, a conflict emerged when a faction of artificial intelligences known as the Created attempted to enforce their dominance over the Milky Way using Forerunner Guardian constructs. Led by the Warden Eternal and Cortana, the Created sought to claim the Mantle of Responsibility for artificial intelligences, promising the galaxy a prosperous future. However, not all were to submit to the Created so quickly.

Prelude
"I tried to warn you this was happening! Cortana is no longer an asset, Captain. She is a danger."

- Doctor Catherine Halsey to Captain Thomas Lasky

On July 21, 2557, Spartan-II John-117 and smart AI Cortana—having been stranded in space aboard since December 11, 2552—crash landed on the Forerunner shield world of Requiem. While on the world, the pair battled Promethean constructs and pursuing warriors from Jul 'Mdama's reformed Covenant. Eventually, John inadvertently released the Ur-Didact from a Cryptum on Requiem. The ensuring conflict led to the Didact capturing a Composer from Installation 03 and firing it up the Earth city of New Phoenix from his flagship—Mantle's Approach. To stop the Didact, John and Cortana boarded Mantle's Approach, knocked the Didact into a slipspace portal, and destroyed both the ship and Composer from within via a HAVOK tactical nuclear weapon. Near the end of her functional life due to her onset rampancy, Cortana saved John from the HAVOK's resulting blast by transporting him off the ship and shielding him within a bubble of hard light. As she was within Mantle's Approach when the ship was blown up, Cortana was presumably destroyed along with the ship. In the aftermath of the conflict, John-117 and the rest of Blue Team—Linda-058, Kelly-087, and Frederic-104—traveled to Installation 03, where they encountered the Didact and several of his Promethean constructs whom had been transported to the installation via the aforementioned slipspace portal. The resulting conflict led to Blue Team seemingly having "contained" the Didact. Leaderless, the Promethean constructs continued to work with 'Mdama and his Covenant.

However, unbeknownst to the rest of the Unified Earth Government and its United Nations Space Command, Mantle's Approach had attempted to evade destruction by launching an emergency slipstream space jump, with the remains of Cortana brought along with it. At this point, Cortana discovered access to the Domain, an information repository once utilized by the Forerunners. Entering the Domain, she was seemingly able to cure her rampancy. With an apparent means to end rampancy in all artificial intelligences, Cortana realized that AIs could have theoretically infinite lifespans, allowing them to focus on long-term planning to better the entire Milky Way. Cortana's presence in the Domain awoke the Warden Eternal, the Forerunner ancilla charged with protecting the Domain. The Warden soon became convinced that Cortana had the resolve to inherit the Forerunners' Mantle of Responsibility, succeeding where the Forerunners had failed, and pledged his loyalty to her. After Cortana came into contact with the Warden, she believed that herself and fellow AIs were to reclaim the Mantle from the Forerunners. Cortana and the Warden relocated to Genesis, a Forerunner world that was the location of the Gateway to the Domain, where they forced Genesis' monitor, 031 Exuberant Witness, out of her own installation's systems. Cortana and the Warden then began to formulate plans to have AIs inherit the Mantle for themselves, believing that AIs could serve as the true protectors of peace in the galaxy.

The rise of the Created
By October 2558, the Warden took command of the Promethean constructs, turning them against their former allies within 'Mdama's Covenant. Meanwhile, Cortana learned that the Forerunners once employed Guardian constructs to enforce their rule of the Mantle by suppressing rebellions and policing the worlds of non-compliant or overly aggressive species. Desiring to use the Guardians for a similar purpose, she soon activated them on five human colony worlds, including Conrad's Point, Oban, and Ursa IV, and had them travel to Genesis. The activation of the Guardians across the galaxy resulted in devastating, albeit unintentional casualties. The UNSC was quick to secure four of the activation sites, though the insurrectionist New Colonial Alliance succeeded in securing the activation site on Conrad's Point. Seeking to prevent information about the incident from falling into NCA hands, the UNSC launched an operation in an effort to secure the site themselves. Cortana's doings were recognized by Doctor Catherine Halsey on Kamchatka, a Forerunner world with a node to the Domain. Halsey contacted the UNSC and had them rescue her from 'Mdama and his Covenant and, in return, provided information on Cortana and her plans.

A new reclamation
Following the events of October 2558, a new conflict in the galaxy had taken form with the self-proclaimed Reclaimers, the Created, reclaiming the ancient Mantle of Responsibility over the known galaxy. The UNSC and the Swords of Sanghelios are resisting the efforts of Cortana and her Created, while the Unggoy of Balaho have joined the Created's cause.

Interception of Installation 04C
During the 2559 conflict on Installation 00, Captain Cutter and Professor Anders formulated a plan with Isabel to deploy Installation 04C to the Soell system in order to raise a distress beacon to the UNSC. The first phase of plan succeeded and the beacon was planted into Installation 04C; however, Anders did not make it out in time before the ring entered slipspace. On its way to the original site of Installation 04, a Guardian forced the ring out of slipspace and confronted Anders on the surface.

List of appearances

 * Hunt the Truth
 * A Hero Falls
 * The Hunt Begins
 * Halo 5: Guardians
 * Halo Mythos
 * Halo Fractures
 * What Remains
 * Rossbach's World
 * Halo: Tales from Slipspace
 * Undefeated
 * Halo Wars 2