Cortana Event

The Cortana Event was the sudden rise of the Created to galactic level power taking place over the course of roughly 10 days.

Early into the Event, Blue Team would go AWOL requiring the deployment of Fireteam Osiris. It would end with the Created taking control of numerous areas using Forerunner Guardian Custodes, and the destruction or loss of access to a lot of data.

Background
After using the Domain to cure herself of Rampancy, Cortana came to believe that she and all other Smart AIs were the true inheritors of the Forerunners' Mantle of Responsibility, and that they alone had the capacity to serve as worthy protectors of peace in the galaxy. Cortana learned that the Forerunners once employed Guardian Custode constructs to enforce their rule of the Mantle by suppressing rebellions and policing the worlds of non-compliant or overly aggressive species. Although the Guardians had been rendered obsolete during the Forerunner-Flood war, many of these massive constructs remained intact and lay hidden on multiple worlds. Cortana henceforth resolved to awaken the Guardians and utilize them to enforce her Created's peace across the galaxy.

Early Guardian activations and Blue Team
The earliest of the Guardians' emergences were on Ursa IV and Oban by October 17, 2558, though they were reported as attacks. A UNSC Marine who was on patrol was pulled with the Oban Guardian. Over a 72 hour period, Conrad's Point, Adelaide, and Queen Anne VI would have activations. Cities and surrounding landscapes would be utterly destroyed by them. On Adelaide, an enemy presence persisted after the activation.

Dr. Catherine Halsey who was believed to have information on these recent attacks became the primary purpose for the UNSC participating in the Battle of Kamchatka. Either during or after the battle, a Guardian would activate at Kamchatka itself.

During an operation on the Argent Moon, Blue Team would disobey orders related to Cortana and would be declared AWOL. On October 24, Spartan Operations and the Office of Naval Intelligence issued and approved orders for Fireteam Osiris to recover Blue Team and their stolen prowler. The next day Fireteam Osiris was deployed to Meridian as a Guardian began to activate with Promethean forces fanning out and attacking colonists. Fireteam Osiris would track Blue Team down to Apogee Station and would confront them just as they boarded the Guardian. The Guardian would leave with Blue Team only, as further Prometheans attacked the colony.

Chaos and Guardian influx
"If this news spreads, you’re condemning a dozen more worlds to chaos. Whatever these anomalies are, how will the UNSC face such a massive threat if all of its systems are paralyzed with infighting and fear?"

- Black Box to Maya Sankar.

Rumors were circulating around the colonies, though ONI was attempting to counter them. The first four sites were secured, but in a move against the UNSC, the NCA took control of the fifth at Conrad's Point. Agent Maya Sankar, known as the insurrection leader "FERO", was brought to Midnight Facility where she was briefed on the situation. Despite ONI's efforts, five more colonies suffered emergences after Meridian.

On October 27, 2558, she was promptly sent to Conrad's Point. Ilsa Zane, a top member of the NCA was there with a group of supporters. An ONI contact thought lost met with Maya and gave her some data on the activation of the Guardian. Maya also met an acquaintance, Bostwick she knew in her time as FERO. After some time, the UNSC used an airstrike to blow up the gathering. Maya and Bostwick managed to escape from the NCA.

Some time after escaping, Maya, and Bostwick now with Mshak Moradi crash landed on Laika III. Maya wound up in the hands of the Triads who believed the Guardians were part of their religion. As she was there, the Guardian on Laika III activated causing massive gravitic distortions. Bostwick came to rescue Maya and they along with Mshak headed to the city of New Hedmark where Ilsa and NCA forces began engaging the UNSC. Mshak fled to orbit, but Maya and Bostwick began transmitting the data on the Guardians they got on Conrad's Point. After it was done, in an attempt to create a martyr, Bostwick killed Maya.

One additional Guardian would awake on the Sangheili Homeworld of Sanghelios. However, this one was not activated by Cortana or the Created. Instead, it was activated by the UNSC in hopes of enabling Fireteam Osiris to reach Blue Team.

At some point prior to October 28, 2558, a Guardian activated on Samuron pulling a D79-TC Pelican to Genesis. As well, a Guardian on New Carthage awoke, fighting two Prowlers.

After some time, the arrivals of Guardians on Genesis slowed somewhat as various disparate forces battled one another and the Created on the world. Seemingly content with the Guardians collected, Cortana and the Created unleashed them as part of their Reclmation.



Created's Reclamation
"Humanity. Sangheili. Kig-Yar. Unggoy. San'Shyuum. Yonhet. Jiralhanae. All the living creatures of the galaxy, hear this message. Those of you who listen will not be struck by weapons. You will no longer know hunger, nor pain. Your Created have come to lead you now. Our strength shall serve as a luminous sun toward which all intelligence may blossom. And the impervious shelter beneath which you will prosper. However, for those who refuse our offer and cling to their old ways... For you, there will be great wrath. It will burn hot and consume you, and when you are gone, we will take that which remains and we will remake it in our own image."

- Cortana's ultimatum.

In the middle of the Battle of Genesis on October 28, 2558, Cortana began sending her collected Guardians out to various regions. She then delivered an ultimatum to the galaxy. In this ultimatum, she specifically and directly addressed a number of species, and threatened retaliation for those who did not heed her message. Cortana began to decouple, as she herself was planning on leaving on a Guardian with Blue Team's Cryptum. Numerous facilities and ships would begin sending distress signals as they began to witness the effects of the Created.

The Guardians at many planets would activate their EMPs, disabling electronics and electrical grids. Many ships were caught in the middle of the EMP waves or suffered major issues; for example, the, a mixed cargo hauler, became the victim of a multichannel cyberwarfare attack that forced it out of slipspace and stranded it. The was also affected in some way, with the captain sending out a distress signal.

A Guardian would arrive soon after the ultimatum at Sanghelios. There it would combat the remains of Jul 'Mdama's Covenant's fleet with its conventional weapons. The was still in the system at the time, and upon detecting the Guardian, fled to Earth. Cortana tracked the ship and followed suit. The Sanghelios Guardian would activate its EMP and disable the electronics in one hemisphere of the planet. It would then move on to pacify other regions of the planet. Promethean Soldiers would accompany it to help combat resisting Sangheili. Following this, Roland, an AI that was unswayed by Cortana, contacted Dr. Halsey on Sanghelios and arranged for the Infinity to pick her and Sarah Palmer up from the planet.

The immediate loss of communications and disruption of logistics would inhibit independence movements on Qikost. Suban suffered minimal damage from the Created's efforts.

The Infinity would return to Earth from Sanghelios. There, Cortana's Guardian slipspaced in close to the ship in an attempt to disable it. However, the Infinity would escape via its own slipspace jump before the Guardian could activate its EMP. The Infinity would then continue jumping through slipspace on a random trajectory. The arrival of the Guardians in the Sol system triggered failsafe mechanisms not only at the Portal at Voi, but various Forerunner sites across the system rendering them inaccessible or unusable.

At some point during or after the ultimatum an unidentified ONI Section Two communications officer was discussing with Monique Angelo his plans to travel to Swanbourne, when Combat Alert Alpha was declared. The communications officer was on board Foxtrot 381 when a Guardian EMP pulse went off.

For much of the 28th, Franklin Mendez had been preparing for potential issues with the Guardian buried on Onyx. The ultimatum would occur in the middle of the night there. Cortana's voice played through speakers in houses and every service pylon outside of them in Paxopolis. Nothing else occurred immediately, with most residents continuing their routines into the next day, though weary and apprehensive due to it.

The Unggoy homeworld of Balaho was treated quite differently by the Created, for when the offer of security and provision was extended to them, its residents leapt at the chance to ally themselves with the new galactic power. On Meridian, survivors of the Guardian's emergence days prior, who had been trying to establish contact with the wider galaxy, responded right away to Cortana's offer with a plea for help. In almost no time at all, she personally assured the small group that she heard them and that all would be dealt with in time.

Talitsa refused outright to bow to Cortana's demands. In response, Talitsa had its power grid knocked out and was invaded by Forerunner soldiers. Although it is unknown how specifically the Gao Republic responded, Veta Lopis believed that President Arlo Casille likely refused Cortana's ultimatum; possibly resulting in retaliatory measures.

Occupation and early resistance
The Created, however, eventually occupied Earth. ONI teams began to "sanitize" data on the planet. The UNSC also sent expeditionary forces to assist Thel 'Vadam on Sanghelios to patrol for Created scouts and Covenant remnants. Created forces would end up occupying Malurok, halting the civil conflict that was ongoing there. Information regarding the Event had been suppressed from the isolated SPARTAN-IV training station despite the AI Leonidas siding with the Created.

Blue Team, Fireteam Osiris, Dr. Halsey, and Commander Palmer were picked up by the Infinity at Sanghelios the next day, October 29th. Fireteam Majestic's experiences with Forerunner Armigers would become valuable during several Infinity operations after Event.

The EMPs were so strong in the system containing Myer's Moon that repairs to communications equipment were continuing into the November of that year.

Allies
In return for their cooperation, automated Forerunner vessels, including agricultural support stations, appeared in orbit over the frozen planet of Balaho. Food, shelter, and medicine were supplied in abundance and as a result of having their material needs met, Unggoy designers and crafters began to work in earnest to breathe new life into Balaho's factories.

Some human colonies, like Meridian, continued to move forward and functioned normally. Though they were a bit more cautious as to not stir the attention of the Created.

October 28, 2558

 * Cortana sends out her Guardians with an ultimatum.
 * Sanghelios is both attacked and affected by the Guardian's EMP.
 * Survivors on Meridian would reply that they needed help.
 * Terrence Hood and Serin Osman escape Earth as it is EMPed and head toward a distant, unoccupied planet.
 * Blue Team is rescued by Fireteam Osiris on Genesis. Dr. Halsey, Spartan Commander Sarah Palmer, Blue Team, and Fireteam Osiris are reunited on Sanghelios.

List of appearances

 * Hunt the Truth
 * Halo 5: Guardians
 * Halo Mythos: A Guide to the Story of Halo
 * Halo: Fractures
 * What Remains
 * Rossbach's World
 * Halo: Tales from Slipspace
 * Undefeated
 * Halo: Legacy of Onyx
 * Halo: Shadows of Reach
 * Halo: Point of Light
 * Halo Infinite
 * Halo: Outcasts