Editing Catherine Halsey

|variant=Human

|name=Catherine Halsey

|homeworld=[[Endymion]]<ref name="WaypointCatherineHalsey">[https://www.halowaypoint.com/en-us/universe/characters/catherine-elizabeth-halsey '''Halo Waypoint''' - ''Catherine Halsey'']</ref>

|birth=[[2492#March|March 19, 2492]]{{Ref/Reuse|WaypointCatherineHalsey}}

|siblings=

|spouses=

|species=[[Human]]{{Ref/Reuse|WaypointCatherineHalsey}}

|gender=Female{{Ref/Reuse|WaypointCatherineHalsey}}

*{{Convert|117|lb|kg|disp=flip}} {{C|post-amputation}}{{Ref/Reuse|WaypointCatherineHalsey}}

|hair=*Gray{{Ref/Reuse|WaypointCatherineHalsey}}

|eyes=Blue{{Ref/Reuse|WaypointCatherineHalsey}}

|affiliation=[[Office of Naval Intelligence]]{{Ref/Reuse|WaypointCatherineHalsey}} {{C|formerly}}

===Early life and education===

{{Quote|The Office of Naval Intelligence had apparently had their eye on me for years and knew that the only way to convince me to join them was to get ''me'' to convince me. It worked. I joined.|Catherine Halsey recalls her recruitment by ONI in [[Dr. Halsey's personal journal|her journal]].}}{{Ref/Reuse|HJ12410}}

Catherine Elizabeth Halsey was born on [[2492#March|March 19, 2492]] within the colony of [[Endymion]]'s coastal city of [[Port Vernon]].{{Ref/Reuse|WaypointCatherineHalsey}} While an impressionable young child, her father recited to her every adventurous tale of [[Wikipedia:L. Frank Baum|L. Frank Baum]]'s [[Wikipedia:Land of Oz|Oz]].<ref name="HJ9447">''[[Dr. Halsey's personal journal]]'', ''September 4, 2547''</ref> At this age, she was already contemplating ideas having to do with [[artificial intelligence]]s and their longevity.{{Ref/Reuse|HJ9447}} As an adolescent, she was already smarter than her parents and was continually reading, learning, and talking, being eager to share her knowledge with anyone who would listen.<ref name="HTFOR25">''[[Halo: The Fall of Reach]]'', ''Chapter 25''</ref> Among the works Halsey read was an [[English]] translation of [[Wikipedia:Dante Alighieri|Dante]]'s ''[[Wikipedia:Inferno (Dante)|Inferno]]''.{{Ref/Reuse|HG18}} The first game of [[chess]] Catherine that played with her mother was the only one she ever lost to her.<ref name="HJ11749">''[[Dr. Halsey's personal journal]]'', ''November 7, 2549''</ref> Upon beating her daughter she had said, in [[Human languages|Italian]], "When the game is over, the king and pawn go into the same box."{{Ref/Reuse|HJ11749}} At a young age, Halsey was sent to the elite academy [[Endymion Gifted]], where she continued to defy educatory standards. She was eventually afforded a trip to [[Circumstance]] in [[2501]] from the Dean of Biological Science at [[Koletre-Browning University]], who completely funded her education until the completion of her second doctoral thesis sometime after her fifteenth birthday in [[2507]].{{Ref/Reuse|WaypointCatherineHalsey}} While working on that second thesis, Halsey learned various [[Wikipedia:Command-line interface|line command]]s, long discarded and forgotten due to their archaic nature, with which she could interact with computer programs.<ref name="HFS13">''[[Halo: First Strike]]'', ''Chapter 13''</ref>  

===Candidate selection===

{{Quote|no=three|q1=We screen these subjects for certain genetic markers. Strength, agility, even predispositions for aggression and intellect. But we couldn’t remote test for everything. We don’t test for luck.|Catherine Halsey|q2=Luck? You believe in luck, Doctor?|Jacob Keyes|q3=Of course not. But we have one hundred and fifty test subjects to consider, and facilities and funding for only half that number. It’s a simple mathematical elimination, Lieutenant. That child was one of the lucky ones—either that or he is extraordinarily fast. Either way, he’s in.|Catherine Halsey|Doctor Halsey defends her peculiar means of testing [[John-117|John]].}}<ref name="HTFOR2">''[[Halo: The Fall of Reach]]'', ''Chapter 2''</ref>

By [[2517#July|July 21, 2517]], Halsey had been provided with her own team, to which she delegated much of the responsibly for screening Outer Colonies candidates for SPARTAN-II.<ref name="HJ72117">''[[Dr. Halsey's personal journal]]'', ''July 21, 2517''</ref> She did this so it might be completed within a reasonable time frame and so that she could personally focus on processing those from a single region of space: [[FLEETCOM Sector Four|Sector 4]].{{Ref/Reuse|HJ72117}} The children from this [[sector]] which met the criteria Halsey had identified in her original study had files assembled personally by her.{{Ref/Reuse|HTFOR2}} In total, one hundred and fifty subjects were to be considered. The Spartan-II program, of which Halsey was the chief scientist and administrative overseer, had only been granted facilities and funding for half that number, however, so only seventy-five would ultimately be selected.{{Ref/Reuse|HTFOR2}}{{Ref/Reuse|HO4}} And even then, an ONI representative reminded Halsey that not all would make it through the [[Project ASTER|augmentation procedures]] when the time came for that.{{Ref/Reuse|HTFOR3}} Vice Admiral Stanforth had agreed to lend Halsey a {{Class|Vancouver|courier}} called the ''Han'', provided that she agreed to at least one naval officer accompanying her.{{Ref/Reuse|HTFOR1}} Halsey was given free reign to choose her attaché and after reading through the file of one [[Lieutenant (disambiguation)|Lieutenant Junior Grade]] [[Jacob Keyes]], she requested him based on his demonstrated ability to keep a secret. Keyes was then, without any explanation provided to him as to why, assigned to pilot the ''Han'', protect the doctor, and otherwise stay out of her way.<ref name="HTFOR1">''[[Halo: The Fall of Reach]]'', ''Chapter 1''</ref>{{Ref/Reuse|HJ72117}} On July 21 Halsey wrote in her journal that she was considering recommending him for permanent reassignment to her staff.{{Ref/Reuse|HJ72117}} The ''Han'' also came with its own dedicated artificial intelligence by the name of [[Toran]].{{Ref/Reuse|HJ72117}}

===SPARTAN-II===

{{Main|SPARTAN-II program}}

Halsey and Keyes had returned to [[Reach]] by [[2517#September|September 10]] and it is on this date that Halsey told [[Déjà]] to let others know she had settled on the final seventy-five subjects.<ref name="HFORBC">''[[Halo: Fall of Reach]]'', ''[[Halo: Fall of Reach - Boot Camp|Boot Camp]]''</ref> Halsey was stationed in low Reach orbit when she gave final approval to kidnap the seventy-four which still remained to be acquired. Halsey later recorded a private spoken journal entry, using [[Encryption code|RED encryption]] and her private key, in which she voiced how regrettable she felt what she was doing was. She had planned to keep the recording private but changed her mind and just had Déjà erase it entirely once she had finished.{{Ref/Reuse|HFORBC}} On [[2517#September|September 15]] Halsey, writing in her journal, expressed that every child had exceeded the selection criteria and her own expectations.<ref name="HJ91517">''[[Dr. Halsey's personal journal]]'', ''September 15, 2517''</ref> She was particularly impressed by two: [[Linda-058|Number 058]], a girl named [[Linda-058|Linda]] who had engineered her own intelligence network at school to spy on her teachers, and John (Number 117), who had won king of the hill forty-five times in the two weeks before their meeting. Halsey noted that [[Caleb Aagard|Number 095]], a boy by the name of [[Caleb Aagard|Caleb]], had never been located. Later that day Halsey added an addendum to her journal entry after [[Retrieval team Gamma]] reported that [[Kelly-087|Number 087]], a girl named [[Kelly-087|Kelly]], had remarkably eluded capture for six hours before coming forward on her own, having believed her capture attempt to be an elaborate game for her upcoming birthday. Gamma's report caused Halsey to ensure new retrieval protocols were implemented to prevent similar mistakes in the future.{{Ref/Reuse|HJ91517}} The next day, [[2517#September|September 16]], Catherine and Jacob Keyes finally parted company after months together.{{Ref/Reuse|HJ91617}} Halsey felt he was beginning to suspect there was more to their incursions than mere field observations so she requested that he be reassigned to the ''Magellan'' with a commission to full lieutenant both for his own protection and the protection of the program. Taken with Keyes, she recalled in her journal on this date an occasion which he had gotten a job done himself rather than waiting for the assistance of a technical crew.<ref name="HTFOR3">''[[Halo: The Fall of Reach]]'', ''Chapter 3''</ref><ref name="HJ91617">''[[Dr. Halsey's personal journal]]'', ''September 16, 2517''</ref> Despite saying their goodbyes on the sixteenth, Halsey and Keyes briefly met once more the following day before parting for good.<ref name name="H91717">[[343 Industries|Halo]] on Twitter 09/17/2517 [https://twitter.com/Halo/status/247786318162186240]</ref> Once all the children had been collected Déjà undertook a psychological evaluation of each and provided the results and her recommendations to Doctor Halsey.{{Ref/Reuse|HTFOR3}} For years after this the doctor kept what she believed was the only set of records concerning the families who had lost children.<ref name="HG18">''[[Halo: Glasslands]]'', ''Chapter 18''</ref>

===Work continues===

{{Quote|I've instructed Déjà to emphasize the history of military training—that to simulate combat conditions, lethal force is often employed; that accidents are an inherent risk... perhaps even inevitable. Mendez spoke with [[Carris-137|the child]]. She understands. She will recover. This bodes well. There will be many deaths before boot is over.|Doctor Halsey considers the cost of the Spartan-II training and expresses optimism about the trainees' psychological hardiness.}}{{Ref/Reuse|HJS2020}}

One day, around five months into training, Doctor Halsey asked to see two children who had made repeated attempts to escape the program: [[Jai-006]] and [[Adriana-111]].{{Ref/Reuse|HTCP8}} When Chief Mendez brought Jai into her office she at first pretended he had been the one to initiate the visit before casually asking if he wanted to leave. The boy responded enthusiastically that he did, so she asked him to recall what she'd said to them all when they'd first arrived. Nodding regretfully at his clear recollection and persistent defiance, she then drew his attention to a small dart which she claimed could induce a selective neural paralysis and cause him to forget all of his experiences on Reach so far. She said that should he break out of the forest surrounding the complex again, he would be shot in the head with one of these darts and wake up in a city with no memory of what had happened, provided it didn't do further damage to him. On the other hand, she advised, he could continue his training under people who cared about what happened to him. To contrast his new life with his old, she told him that when [[State Dorm Five-Five|the orphanage]] on [[Bhuj]] he'd been housed in was called nobody there had even noticed he'd been missing since she had transferred him. Not even Bhuj's vendors, she'd claimed, remembered him. She finished by exploiting his blossoming friendship with Adriana and making him understand that she could also make her forget about him. Halsey told him that this was her final offer: if he tried to escape that night what she'd said about erasing memories would come to pass. If he stayed, conversely, she offered him a family and a chance to be remembered. Adriana's similar meeting with her left the girl in tears later that evening and unwilling to tell Jai what the doctor had said to her.{{Ref/Reuse|HTCP8}}

===ASTER===

{{Quote|no=four|q1=I have doubts, Déjà. I thought the reasons so compelling when we first started Project: SPARTAN. Now? I... I just don’t know.|Catherine Halsey|q2=I have been over the ONI projections of Outer Colony stability three times, Doctor. Their conclusion is correct: massive rebellion within twenty years unless drastic military action is taken. And you know the ‘drastic military action’ the brass would like. The Spartans are our only option to avoid overwhelming civilian losses. They will be the perfect pinpoint strike force. They can prevent a civil war.|Déjà|q3=Only if they survive to fulfill that mission. We should delay the procedures. More research needs to be done. We could use the time to work on [[MJOLNIR]]. We need time to—|Catherine Halsey|q4=There is another reason to proceed expeditiously. Although I am loath to bring this to your attention, I must. If the Office of Naval Intelligence detects a delay in their prize project, you will likely be replaced by someone who harbors... fewer doubts. And regrettably for the children, most likely someone less qualified.|Déjà|Halsey shares her concerns with Déjà.}}{{Ref/Reuse|HTFOR6}}

On [[2525#February|February 23, 2525]] Halsey got a chance to have a long chat with [[John-117|John]] during which, to her surprise, she learned he was convinced the Spartans were to enter a new, more severe phase of training.<ref name="HJF2325">''[[Dr. Halsey's personal journal]]'', ''February 23, 2525''</ref> Writing in her journal, she expressed her desire to share everything she could concerning the upcoming [[Project ASTER|augmentations]] and wondered if any of them would refuse were she to offer them the choice of whether or not to proceed. Déjà had continued to update and run Catherine's revision of [[Elias Carver]]'s model weekly by this point, and the results were only growing worse. This data made Halsey more resolute in her conviction that nobody involved had any choice but to forge the Spartans.{{Ref/Reuse|HJF2325}} Five days later, she gave birth to her daughter, [[Miranda Keyes|Miranda]].<ref name="WaypointMirandaKeyes">[https://www.halowaypoint.com/en-us/universe/characters/miranda-keyes '''Halo Waypoint''' - ''Miranda Keyes'']</ref> Near the end of February Halsey and the rest of her team sent their prototype suit of [[Mjolnir]] armor to [[UNSC Special Forces|Naval Special Weapons]] for evaluation.<ref name="HJ63025">''[[Dr. Halsey's personal journal]]'', ''June 30, 2525''</ref>

On March 9, the day before [[Project ASTER|Project: ASTER]] was to be initiated, Halsey and the seventy-five teens could be found aboard [[Medical Facility Endurance]] in orbit over Reach.<ref name="HTFOR6"/> At 1130 hours the doctor was pacing in the observation room while she waited for Déjà to decrypt [[UNSC Priority Transmission 09872H-98|a transmission]] from Vice Admiral [[Ysionris Jeromi]]. Catherine had previously proposed a hypothetical series of experiments involving [[Wikipedia:Bonobo|bonobo]]s to he and his team in order to obfuscate her true intentions for the protocols. To her dismay, the latest from Jeromi informed her that further analysis had failed to yield viable alternatives that might mitigate any of the risks inherent to her "hypothetical" experimentation. As soon as she was finished with the file he'd sent Halsey erased all traces of it and even sent Déjà to track its pathways all the way back to the {{UNSCShip|Hopeful}} to destroy his related notes and files. Given the news, Halsey seriously considered delaying the procedures and only put such thoughts aside due to Déjà pointing out that ONI would only find someone else to move the project forward if she started dragging her feet. Chief Mendez met the doctor in the hall outside the observation room and at her insistence followed her up the stairs to the hospital's pre-op wing. Upon seeing John in Room 117 she forced a smile and asked how he was feeling. John, thinking of the procedures as just another exercise, asked her if she could just this once tell him how to win. To that, she could only lean in close and tell him he needed to survive.{{Ref/Reuse|HTFOR6}} Later that day Halsey divided the various augmentations into two groups according to their risks of failure or long-term side effects not adequately studied.<ref name="HJ3925">''[[Dr. Halsey's personal journal]]'', ''March 9, 2525''</ref> Those that she considered to have unacceptable fail rates were to be tabled for then in order that further research could be done. Already she had begun to quietly arrange [[Operation: TENDRIL|long-term studies]] on the gradual application of cyclo-synthetic neural transmission gene sequences during subjects' early lives and noted in her journal that research on the injection of [[Wikipedia:Virus|viral]] [[Wikipedia:Neutrophil|microphage]]s at neuron surfaces was pending. Halsey closed that day's journal wishing there was a god to pray to.{{Ref/Reuse|HJ3925}} As she was being readied for the procedures within Lab 7, Halsey visited the girl [[Yasmine Zaman|Yasmine]] and assisted a nurse in strapping her down.<ref name="ILBPM">''[[i love bees]]'', [[Princess Monologue|princess monologue]]</ref><ref name="ILB12">''[[i love bees]]'', ''[[Axon Clips Chapter 12|Chapter 12]]''</ref> She attempted to reassure the girl that she would barely feel anything apart from slight pain that accompanies injections.{{Ref/Reuse|ILBPM}}{{Ref/Reuse|ILB12}}{{Ref/Note|In the [[Axon Clips Chapter 11|eleventh chapter]] of ''[[i love bees]]'' the A.I. [[Durga]] recites the date [[2537#September|September 16, 2537]] immediately after mentioning Yasmine's involuntary recruitment for the Spartan-II program. Following this recitation Durga mentions Yasmine's post-procedural designation as a medical washout. It may be likely that an error was introduced by seemingly having records which show her as having been abducted for the Spartan-II program years after Project: ASTER had been initiated. Whether the given date actually refers to her original childhood conscription, however, is not completely clear. She is also stated to have died prior to [[2546#January|January 2546]]. The possibility exists that each given date is in error due to having twenty years mistakenly added to the dates [[2517#September|September 17, 2517]] and [[2526#January|January 2526]].}} While visiting [[Serin-019]] before the procedures commenced the girl asked her how different she would feel when she woke up.{{Ref/Reuse|HG15}} Halsey was honest with her and let her know just how painful and persistent the side effects of the surgical enhancements would be if she survived—possibly lasting months or even years.{{Ref/Reuse|HG15}}

===Time of testing===

{{Quote|no=three|q1=Something has happened, Chief. Something ONI and the Admiralty never expected. The brass wants to deploy the Spartans. They want to test them in a real combat mission.|Catherine Halsey|q2=They’re as ready for that as I can make them. But this is far ahead of your schedule. What happened? I’ve heard rumors there was some heavy action near [[Harvest]] colony.|Franklin Mendez|q3=Your rumors are out-of-date, Chief. There’s no more fighting at Harvest. There ''is'' no more Harvest.|Catherine Halsey|Halsey breaks the horrifying news about Harvest to Chief Mendez.}}{{Ref/Reuse|HTFOR8}}

By [[2525#September|September 1, 2525]], Halsey had begun applying the new liquid metal crystal version of [[polymerized lithium niobocene]].<ref name="HJ9125">''[[Dr. Halsey's personal journal]]'', ''September 1, 2525''</ref> Its amorphous nature allowed it to be "poured" into a capillary system where microelectric fields could direct crystallization geometries. The material scaled fractally to double a Mjolnir wearer's strength, but Halsey believed she could exceed even this were she to ignore what she considered archaic safety regulations. In her journal she defended such a move by arguing that nobody had anticipated this technology when such regulations were put in place.{{Ref/Reuse|HJ9125}} Over the next ten days, Halsey spent some time on another trip that took her away from the [[Epsilon Eridani system]].{{Ref/Reuse|HTFOR8}} At one some point during this period [[Déjà]] brought to her attention a transmission from the planet [[Harvest]] in the [[Epsilon Indi system]] which the A.I. had been attempting to decode.{{Ref/Reuse|HTFORTAS}}{{Ref/Reuse|HTFOR8}} Halsey had Déjà show her what little she had and also asked for a feed from the planet, but nothing of the sort was accessible. The doctor urged her to keep trying.{{Ref/Reuse|HTFORTAS}}  

{{Quote|no=five|q1=May I suggest that we go to battle stations, Captain?|Catherine Halsey|q2=I don't see the point.|Wallace|q3=We haven't let this be widely known, but when the aliens were first detected at Harvest, they appeared at extreme range... and then they were suddenly much closer.|Catherine Halsey|q4=An intrasystem jump?|John-117|q5=Correctly surmised, Spartan.|Catherine Halsey.|Doctor Halsey makes sure the ''Commonwealth''{{'}}s captain knows the threat posed by the Covenant in [[space warfare|naval engagements]].}}{{Ref/Reuse|HTFOR12}}

At some point following October 7, Doctor Halsey officially requested access to [[ONI Colonial Security Estimate 2525.10.110|the data archive]] of an [[RQ-XII Drone|RQ-XII drone]] originally deployed from the {{UNSCShip|Walk of Shame}} and recovered by the {{CMAShip|Heracles}} at [[Harvest]].{{Ref/Reuse|HCHE}} Her request was granted with a warning that all queries would be logged in accordance with [[Office of Naval Intelligence Protocol A1|protocol]]. Halsey searched the archive using the keywords "AO.AI", "Mack" "rampancy" and "lifespan limits". The data captured in the log was formed of messages from the agricultural operations A.I. [[Mack]] intended for [[Sif]], the planet's shipping operations A.I. The garbled messages demonstrated the A.I.'s descent into rampancy over a period of eight months.<ref name="HCHE">''[[Halo: Contact Harvest]]'', ''Epilogue''</ref> The ''Pioneer'' did not return to [[Reach]] until [[2525#November|November 2 of 2525]].{{Ref/Reuse|HTFORTAS}} At 0600 hours that day Halsey met the Spartans within the same secure briefing amphitheater where she'd introduced herself to them years earlier.<ref name="HTFOR11">''[[Halo: The Fall of Reach]]'', ''Chapter 11''</ref> They were also joined by Chief Mendez and Admiral [[Michael Stanforth|Stanforth]], who informed the teenagers that [[Harvest]] had been [[First Battle of Harvest|annihilated]] some time ago by what appeared to be alien attackers. The adversary responsible called itself "the Covenant" and had broadcast a message announcing that the destruction of [[humanity]] was the will of its [[Forerunner|god]]s. Stanforth told them that the UNSC had been ordered to full alert and that the largest fleet action in human history was being mobilized in response. And because of the UNSC-wide mobilization, the Spartans' training was to be accelerated to its final phase: [[Mjolnir|Project: MJOLNIR]]. Halsey spoke briefly with Mendez and Stanforth following the meeting's conclusion before leaving with the admiral.{{Ref/Reuse|HTFOR11}} At some point soon after the revelation of their new alien enemies, the doctor and others made sure to add a refractive coating to the design of the shell for each set of armor in order to disperse energy weapon attacks.<ref name="HTFOR13">''[[Halo: The Fall of Reach]]'', ''Chapter 13''</ref> By [[2525#November|November 6]], Halsey and the Spartans had departed [[Reach]] aboard the {{Class|Paris|heavy frigate}} {{UNSCShip|Commonwealth}}.<ref name="HTFOR12">''[[Halo: The Fall of Reach]]'', ''Chapter 12''</ref> The next three weeks were spent handling a variety of minor missions under her guidance on their way out to [[Chi Ceti IV]] on the edge of [[UNSC]]-controlled space. All of the Spartans worked together to put down multiple insurrectionist factions on [[Jericho VII]] and also to remove a [[black market]] bazaar near the [[Roosevelt military base]].{{Ref/Reuse|HTFOR12}}<ref name="HBB17">''[[Halo: Battle Born]]'', ''Chapter 17''</ref><ref name="Dispatch">[https://www.halowaypoint.com/en-us/news/discovery-dispatch-february-21-2019 '''Halo Waypoint''' - ''Discovery Dispatch'']</ref>  

It was at 1750 hours on [[2525#November|November 27]] that the ''Commonwealth'' finally emerged in real space in the [[Chi Ceti system]].{{Ref/Reuse|HTFOR12}} Halsey then immediately summoned John to the bridge, where she waited with the ship's Captain [[Wallace]]. The doctor called his attention to a screen displaying deconvoluted radar signals, including one which was repeatedly appearing and might represent another ship eighty million kilometers away. Though Wallace didn't see the need Halsey urged that they go to battle stations and let him and John know that at Harvest the aliens had been observed making an intrasystem slipspace jump, something beyond the capability of human technology. This new information was enough to change the captain's mind and before long the ship had changed its heading and its bulkheads had been sealed. The doctor informed John that they'd be taking one of the ''Commonwealth''{{'}}s dropships to the surface of [[Chi Ceti IV]] and instructed him to get the others ready to depart, seeing as it was vital the Spartans reached Project: MJOLNIR before the [[Covenant]] did. Almost immediately after he'd relayed orders to muster them [[Unrelenting|an alien ship]] [[Maugen-pattern armored cruiser|a third]] the size of the ''Commonwealth'' suddenly appeared three thousand kilometers off its prow. Both vessels quickly engaged one another and Halsey was surprised to see that even a Covenant ship of such small size was equipped with [[energy shielding]]. Even a direct hit from the frigate's [[Magnetic Accelerator Cannon|magnetic accelerator cannon]] only served to disable its shields rather than destroy the ship. Captain Wallace gave orders to ready another round at that, but Halsey argued against this, instead imploring him to initiate evasive maneuvers. Having the doctor second-guess his command led the captain to threaten her with being ''gagged''. Yet soon enough they were been struck amidships by the enemy's weapons and multiple decks had melted in Section One. When fires were reported throughout various sections Catherine suggested the crew don [[respirator pack]]s so the atmosphere could be vented on all decks outside the [[bridge]] and this time, Captain Wallace assented to her recommendation. When he demanded to know what they'd been hit with she explained that the aliens could evidently [[Plasma torpedo|guide]] the trajectory of [[Plasma weaponry|plasma]] through space. Their MAC system having been destroyed, Halsey next floated the idea of attacking with [[Nuclear weapon|nuclear missile]]s but was once more rebuffed by Wallace since the enemy was far too close to them to make their use safe. Both she and John then concluded that using [[GA-TL1 Longsword]]s to distract the aliens could afford them the safe distance they would need to use nuclear weaponry. To their dismay the smaller ship still remained intact, although obviously crippled, after being hit with the blast of a [[Shiva-class nuclear missile|Shiva-class warhead]]. For her part Halsey could at least appreciate that even if they couldn't destroy the enemy's ships they could evidently at least slow them. With the Covenant craft moving off Wallace ordered the ''Commonwealth'' to execute a [[Wikipedia:Planetary flyby|flyby orbit]] so that Halsey and the teenagers could depart for the [[Damascus Materials Testing Facility]] in [[Vhalkem]] as they passed by it. He told the doctor he would attempt to lead the Covenant ship away if it came back but that they should plan to reconvene in orbit no later than 1900 hours. She immediately turned back to John and told him to they needed to hurry, as there was much she had to show the Spartans.{{Ref/Reuse|HTFOR12}}

{{Quote|Even though this technology will save humanity in [[Human-Covenant War|the war to come]], I must remind myself: liquid crystal cannot rise on its own. [[Titanium]] alloy cannot prevail in the face of extinction. Armor cannot hope. It all means nothing until you step inside.|Halsey shares her thoughts with her Spartans.}}{{Ref/Reuse|BSI}}   

After landing, it took around fifteen minutes for a freight elevator to carry Halsey and the Spartans down into the depths of [[Chi Ceti IV]], finally depositing them in an underground hangar at around 1845 hours.{{Ref/Reuse|HTFOR13}} Catherine only had to clear her throat to garner the attention of the space's three technicians and to make at least a dozen A.I. avatars vanish from view. She then wasted no time introducing the Spartans to Project: MJOLNIR and breaking down the basic parts of the armor suite for them.

===Alpha Corvi II===

{{Main|Battle of Alpha Corvi II}}

{{Quote|no=three|q1=UNSC Command is pleased... But they still don't trust the Spartan-II project.|Catherine Halsey|q2=So we noticed.|Linda-058|q3=There is concern that your presence will negatively influence marine battle readiness. Luckily for you, Alpha Corvi II provides another chance for you to prove yourselves.|Catherine Halsey|Doctor Halsey provides motivation for John, Fred, Kelly, and Linda.}}<ref name="HCD1">''[[Halo: Collateral Damage]]'', ''[[Halo: Collateral Damage Issue 1|Issue #1]]''</ref>

On [[2525#December|December 3, 2525]], Halsey met with [[Blue Team]] within the ready room assigned to it on the ''[[UNSC Persian Gate|Persian Gate]]'' while still ''en route'' to the [[Alpha Corvi system]].{{Ref/Reuse|HCD1}} She stated that seeing as they had had the past two days to get used to the idea, in their gut, that a [[Spartan]] fall in battle, it was now time to put their grief aside. She told them that though they should honor that emotion, it would only be a hindrance to the [[Human-Covenant War|upcoming fight]] they were sure to be sorely needed for. [[Lieutenant Commander]] [[Yao]] entered then and took it upon herself to brief the team on the [[Covenant]]'s present [[Battle of Alpha Corvi II|attack]] on [[Alpha Corvi II]]. She explained the role Blue Team was to play in the defense of [[Jamshid]], the planet's largest city, but then left the remainder of the briefing to Halsey. Once Yao had left, Halsey encouraged the four teens by letting them know the [[Mjolnir]] armor had performed better than had been hoped for during the [[Battle of Chi Ceti|engagement]] at [[Chi Ceti IV]] and that much of that had been due to their operating skills. And though she could say that UNSC Command was pleased, she reminded them that the Spartan-II project still wasn't trusted and that there was especially concern that their presence could negatively influence [[marine]] battle readiness. Luckily for them, she offered, Alpha Corvi II just provided another chance for them to prove themselves. Once an [[A.I.]] aboard the ''Persian Gate'' named [[Nora]] provided Doctor Halsey with updated medical scans for each member of Blue Team, she confirmed with John that he was well enough to fight. She also asked whether he would tell her if he wasn't to which he simply said that she'd find out if that ever happened. Taking her leave, she instructed the Spartans to suit up as they'd be exiting slipspace within thirty minutes. She later rejoined them after they'd arrived at the colony to see them off. During the Spartans' insertion via [[D77-TC Pelican]], she remained in contact with them and let them know that while their first priorities were the neutralization of the enemy and the defense of [[Black Reef]], a mining settlement they'd been redirected to after the ''Persian Gate'' was contacted by the ground, she also wanted them to try to find out why the aliens were targeting it specifically. She asked that they pay attention to the enemies' tactics, unit composition, weapons. As the craft drew near its landing zone, she closed by telling the four of them not to expect any help from marines on the ground, as Command didn't want the two groups interacting.{{Ref/Reuse|HCD1}}

===Etalan===

{{Main|Battle over Etalan}}

{{Expand-section}}

===Total War===

{{Quote|[[Michael Stanforth|Vice admiral]] ordered us to repurpose ''everything'' to quell the Covenant threat, and to refocus our research on wartime strategy. I couldn't agree more (it was, after all, my idea).|Catherine takes note of the UNSC's shift in priorities within her [[Dr. Halsey's personal journal|journal]].}}{{Ref/Reuse|HJ42826}}

Thirteen days later, on [[2526#April|April 28]], Halsey noted in her journal that Vice Admiral Stanforth had ordered she and others to repurpose everything to quell the [[Covenant]] threat and to refocus their research on wartime strategy.<ref name="HJ42826">''[[Dr. Halsey's personal journal]]'', ''April 28, 2526''</ref> She couldn't have agreed more, seeing as doing just that had been her idea to begin with, though she did sarcastically ask if the [[Insurrection]] would adhere to the policy as well. By this time Halsey had learned [[ONI]] [[ONI Section Two|Section Two]] had sent emissaries to leaders in the [[Outer Colonies]] to warn them of the Covenant and to make them offers of peace. Footage from the [[Battle of Bliss|glassing]] of [[Bliss]] generally convinced these leaders of the magnitude of the threat they all faced. In her journal Halsey wondered if the aliens might have solved their civil war—not a trade she would have made, but perhaps a small victory nonetheless.{{Ref/Reuse|HJ42826}} On [[2526#May|May 3]] Catherine reviewed in her journal the distinctions between so-called "[[Smart AI|"smart"]] (volitional) and [[Dumb AI|"dumb"]] artificial intelligences and why the "smart" ones are susceptible to [[rampancy]].<ref name="HJ5326">''[[Dr. Halsey's personal journal]]'', ''May 3, 2526''</ref> She noted that she had devised new matrix strata with random-access optical couplers that could theoretically extend a volitional A.I.'s lifespan, though by exactly how much she was unsure. In simulations a randomly coupled matrix also boosted correlation effects such as accurate guessing. As volitional A.I.s were needed then more than ever to counter the Covenant threat, Vice Admiral [[Michael Stanforth|Stanforth]] had authorized a test run of Halsey's protocols. After leaving herself a reminder to investigate the polarization of topological [[Wikipedia:Soliton|soliton]] pulse transfers she concluded that day's writing by questioning whether she was playing the role of [[Wikipedia:God|God]] or mother in breeding life from non-life, or perhaps simply being beguiled by sentimental anthropomorphism.{{Ref/Reuse|HJ5326}}

===Research Advancements===

{{Quote|The [[Illegal Entry Protocols|illegal entry protocol]]s ("PIE") used for hacking insurgent networks have deciphered a tiny portion of the aforementioned Jackal shield system. Just goes to show that no scrap of genius goes wasted! I've had [[Jerrod]] dedicated all his runtime to further avenues of inquiry—perhaps they can crack more. Already have enough data to run a simulated test for a Mjolnir energy shield system. Moreover, if we can understand their operating systems, we hope to gain insights into their language (their motivations?). ''That'' might prove ultimately of more value than any weapon we could devise.|Catherine Halsey responds to a major breakthrough with enthusiasm.}}{{Ref/Reuse|HJ52044}}

By [[2533#November|November 10, 2533]] Catherine had developed a new theoretical architecture which involved three [[artificial intelligence]]s arranged in parallel.<ref name="HJ111033">''[[Dr. Halsey's personal journal]]'', ''November 10, 2533''</ref> She did this in order to palliate the preemptive severing of neural linkages and ultimate self-termination which characterized third-generation A.I.s, hoping that by leaving all choices to be decided by majority vote the frenzied cutting behavior would be avoided. In her design, ties which arose when one of the A.I.s abstained would resolve at random. Though Halsey knew this could slow overall processing, she was confident such a theoretical trio would deconvolute and divide algorithms to compensate for the loss, and in doing so perhaps even ''accelerate'' processing. Consensus-based decision-making would also be applied to linkage creation in order to forge a superior initial neural linkage. Unfortunately, Halsey could not know how the theoretical trio's overall lifespan might be increased under such circumstances because simulations could not create ''[[Wikipedia:In vivo|in vivo]]'' A.I.s. Writing in her journal on that November [[2533]] date, the doctor wondered what other characteristics could emerge from an A.I. triumvirate. She only had three at her disposal at the time and as such had moved them to the [[Sanderson Private Hospital|Sanderson private hospital]] on [[Beta Hydri VI]] as a precautionary measure. In addition, she kept all knowledge of this from other A.I.s she interacted with. A note from Halsey to herself on November 10 served as a reminder to follow up on reports of [[Mack|nes]][[Loki|ted]] A.I. personalities that were present on [[Harvest]] before it was [[First Battle of Harvest|lost]].{{Ref/Reuse|HJ111033}} A little over a year later, on [[2534#December|December 25, 2534]], Halsey recorded her thoughts concerning an interaction she'd had with a colleague, Doctor [[Forester]], in which she had illustrated increasingly complex sketches for him with the intent to visualize conceptions of space with increasing hyperdimensions.<ref name="HJ122534">''[[Dr. Halsey's personal journal]]'', ''December 25, 2534''</ref> She had been attempting to show him that it was the increased density of cross-linkages which caused wave function collapse, not the creation of the links themselves. If space were not a limiting factor the number of available connections would increase at a geometric rate. Though Halsey considered classic [[Wikipedia:String theory|string theory]] dubious, she thought the eleven (or more) dimensions it predicted could theoretically be accessed by anyone outside the quantum fields which enveloped ships traveling through [[slipspace]]. She was disappointed Doctor Forester apparently failed to grasp that slipspace was open to exploitation within four-dimensional [[Wikipedia:Spacetime|spacetime]]. Writing in her journal following their discussion, Catherine pondered whether remote construction with any exotic matter in the raw slipstream was possible, for at that moment the technology required for that remained at best theoretical. She figured decades or even centuries may pass before the necessary tech and its practical applications arrived. She closed that day's entry wondering whether people were ready for the potentially near-limitless cross-connections and faster-than-light processing speeds A.I.s in slipspace could possess.{{Ref/Reuse|HJ122534}}

By [[2535#November|November 22, 2535]] Halsey had received what were being referred to as the top secret "Hencheck Findings", named for a Lieutenant [[Hencheck]] who had procured a cache of Covenant weapons and miscellaneous artifacts during a skirmish in the [[Indra Asteroid Cluster|Indra asteroid cluster]]. Much about the enemy's weaponry astonished her and made her ask questions about their construction. No traces of production designs could be found within the weapons' architecture, and much of the technology seemed heavily polarized yet uniformly purposed, leading Halsey to think it might have originally been developed for some other purpose or purposes. Regardless, the immediate conclusion she drew from the findings was that humanity still lacked the ability to replicate the Covenant's technology.<ref name="HJ112235">''[[Dr. Halsey's personal journal]]'', ''November 22, 2535''</ref> By [[2536#January|January 10, 2536]] Catherine had gotten [[Leonard Gillespie]], a student of Doctor [[Forester]]'s, transferred to Reach so she could watch him closely.{{Ref/Reuse|HJ11036}} This was due to his recent discovery that a portion of the inner apparatus of a particular [[Kig-Yar]] [[Kig-Yar point defense gauntlet|point defense gauntlet]] in the UNSC's possession had not been sealed. In addition to the gauntlet already being clearly much older than any others encountered, initial testing confirmed that with a massive power input its capacity for creating and sustaining [[energy shield]]ing over a very small surface area could be replicated. The implications such a technological leap could have for MJOLNIR made Halsey determined to get her hands on the artifact.<ref name="HJ11036">''[[Dr. Halsey's personal journal]]'', ''January 10, 2536''</ref> By [[2537#May|May 25, 2537]] Halsey and [[Kalmiya]] had deciphered what they thought could be a root [[wikipedia:Diction|diction]] to a meta-[[Sangheili (language)|Covenant language]] system.{{Ref/Reuse|HJ52537}} Elements of this system had been observed manifesting in the (potentially misnamed) "operating system" the aliens used. Curiously, employing their symbolic logic appeared to counter the accelerated cross-linkage effects in A.I.s. Though her progress in understanding this was moving slowly, it was advancing steadily nonetheless, as she wrote in her journal. She also made a note reminding herself to investigate the possibility that what she was working with might represent dimensional slices of a more complex topology.<ref name="HJ52537">''[[Dr. Halsey's personal journal]]'', ''May 25, 2537''</ref>

===Capture and rescue===

{{Main|Operation: WARM BLANKET}}

{{Quote|no=two|q1=You seem to be in one piece.|John-117|q2=Maybe your luck has rubbed off on me.|Catherine Halsey|Doctor Halsey and John tease one another.}}{{Ref/Reuse|HLTP}}

===A.I. and Slipspace===

{{Quote|Incredible. [10141-026-SRB4695], with minimal influence from this [[The Assembly|Assembly]], has attempted to build an abstract fractal structure within Shaw-Fujikawa Space. Although her first attempt was a failure, success could finally remove our dependence on biological systems altogether! If our Minds could somehow achieve freedom of expansion within eleven-dimensional space, immortality might be within reach.|An [[artificial intelligence]] of the [[Assembly Minority]] theorizes on what Doctor Halsey's experiment could mean for the future of A.I.s.}}<ref name="HRTPDP">''[[Halo: Reach]]'', ''[[The Package]]'' [[data pads]]</ref>

Once she secured access to the drive, she first needed to breach the external, internal, and vacuum coupling shields to the singularity, for which she bemoaned that the UNSC couldn't make a proper pan-[[Wikipedia:Torque|torque]] screwdriver.<ref name="CF74">[https://www.halowaypoint.com/en-us/news/canon-fodder-noble-intentions '''Halo Waypoint''' - ''Canon Fodder: Noble Intentions'']</ref> She would have preferred to use hardened remotes for the breaching, but they would have been detected by networks which would also record their activities. As a result, a peculiar [[Wikipedia:Synesthesia|synesthetic]] effect moved along her left arm up to her neck when she removed the shields. She also experienced a kind of "hiccup" in her awareness which she surmised was due to the [[Wikipedia:Delta timing|delta time]] which could occur with abrupt transitions into slipspace. Next, she had to check the probe's telemetry systems after compensating for how close the experiment was to Reach's [[Gravity well (physics)|gravity well]], and found they were within tolerable variances. Halsey then verified the data of the [[Smart AI|A.I.]] seed "H-7" to seven [[Wikipedia:Significant figures|significant figures]] and initiated its transfer to the matrix strata within the probe. After starting the slipspace drive and verifying the data received, as well as activating the AI seed, she confirmed an initial growth state. Upon checking and triple verifying the probe's telemetry uplinks she then finally launched it on an aligned trajectory. Recording her observations in her journal, the doctor noticed again that time seemed to have mysteriously elapsed, as there was a step anomaly in the chronometer. This had not affected her or her wristwatch as far as she could tell, and she guessed that the anomaly might be a technical artifact or a subdimensional leakage from the probe as it was inserted. It was only then that she realized she had already made a note of this "hiccup" closer to the time it had occurred but could not recall doing so. Telemetry confirmed that A.I. growth was beyond exponential—appearing instantaneous. Halsey wondered variously if this might be explained by the temporal discrepancy, some hitherto undiscovered multidimensional effect on the A.I. cross-linkages, or even alternate physical laws harnessed by the unshielded slipstream. Much of the incoming data and consciousness cross-checks soon became garbled and voice communication from the A.I. was attenuated. Logic/mathematics [[Scriber test]]s confirmed full functionality, but Halsey was disturbed by the conclusions, insights, and even what she considered nonsense being generated. The A.I.'s comments on [[humanity]] and the [[Covenant]] defied reason from her perspective, but she made sure they were all recorded, including those concerning [[The Assembly|other intellects]] in the "mist". Halsey wondered in her journal whether the "mist" referred to [[slipspace]] and also commented on another four-hour "step" in time that might also be explained by lost consciousness. She additionally noted that the data-transfer buffer had been blown—capable of one hundred and forty-eight hours at its maximum rate. As soon as she made this observation Halsey set about replacing it. After the telemetry became fully operational she noticed glaring gaps throughout the record. And although the voice communications continued to grow increasingly nonsensical, all [[rampancy]] indicators were negative.{{Ref/Reuse|CF74}}

===Cortana===

{{Quote|I'm delighted with Cortana. She has assumed a rather simple human appearance (much to my relief; so many of the ONI A.I.s adopt such theatrical personas). Her face resembles mine when I was fresh out of college—so wonderful and naïve, and eager to learn. It's almost like looking in a mirror.|Doctor Halsey's written thoughts on Cortana's chosen avatar.}}

On [[2549#September|September 9]] Halsey reflected on the recent [[Second Fall of Arcadia|loss]] of [[Arcadia]], as she had come into possession of a near-complete record of the attack taken from an orbiting weather satellite.{{Ref/Reuse|HJ72949}} In her journal she expressed the agony viewing the destruction caused her, noting that she knew some would smirk at the thought of her shrinking from it. As the entire world's surface was mercilessly [[Glassing|glassed]] rather than only portions, she wondered variously whether the planet posed a threat to them, had religious or political value, or was simply designated for sending a message to humanity.{{Ref/Reuse|HJ72949}} By September 14 Halsey had hacked into the redacted portions of other Arcadia reports.<ref name="HJ91449">''[[Dr. Halsey's personal journal]]'', ''July 14, 2549''</ref> At some point in September the annex in [[CASTLE Base]]'s Omega Wing where Halsey was working was quarantined.{{Ref/Reuse|HRO}} On [[2549#November|November 7, 2549]], she transferred and authenticated the H-1 specimen's neural pattern to A.I. matrix strata, completing the initiation sequence within normal quantum flux tolerances.{{Ref/Reuse|HJ11749}}<ref name="WaypointCortana">[https://www.halowaypoint.com/en-us/universe/characters/cortana '''Halo Waypoint''' - ''Cortana'']</ref><ref name="HRO">''[[Halo: Reach]]'', ''[[Outpost]]''</ref> The newly made intelligence called herself "[[Cortana]]" and represented a generational leap in volitional A.I. technology.{{Ref/Reuse|HRO}} Halsey placed a viral termination code in her kernel but then could not tell whether she remained unaware of it or had already isolated and bypassed it.{{Ref/Reuse|HJ11749}} Halsey also programmed her with ONI's best insurgency software and every ONI computer insurgency routine, as well as the determination to use those code-cracking skills.{{Ref/Reuse|HTFOR25}}{{Ref/Reuse|HTFOR27}} She first designed and tested these routines on [[Kalmiya]].{{Ref/Reuse|HFS13}} Only once the process had been debugged and streamlined did she incorporate them into Cortana. Afterward, the brass in [[ONI Section Three|Section Three]] instructed Halsey to destroy any prototype routines—an order which she promptly ignored.{{Ref/Reuse|HFS13}}  

On [[2550#November|November 23]] the [[Official Secrets Act of 2550]] was handed down, regulating the confidentiality and nondisclosure of any official [[messenger satchel]].{{Ref/Reuse|HJ112350}} This additional measure struck Halsey as onerous and when she made inquiries regarding it to [[Michael Stanforth|Stanforth]] he uncharacteristicallt deflected them. Catherine speculated in her journal that the new regulation might relate to [[Visegrád]] or some of the other rumored [[Forerunner|sites]] she'd been collecting data on, and while she did appreciate the need for secrecy she did not appreciate relevant data being kept from her. If indeed Visegrád was [[Forerunner|what]] she and others all thought it might be, she reasoned—and if there were other such sites, she wondered who could be positioning themselves to assay the larger picture.<ref name="HJ112350">''[[Dr. Halsey's personal journal]]'', ''November 23, 2550''</ref> By [[2551#February|February 20, 2551]] the {{UNSCShip|Hopeful}}, the UNSC's largest medical facility, had departed Reach with a minimal escort.<ref name="HJ22051">''[[Dr. Halsey's personal journal]]'', ''February 20, 2551''</ref> According to Halsey's own sources, it was accompanied by one ONI prowler in addition to a single destroyer. The ''Hopeful''{{'}}s A.I. was unusually tight-lipped when [[Kalmiya]] asked about its destination. This, plus the late addition of carcinogenic, mutagenic, and experimental chemicals to its manifest among other oddities, piqued the doctor's curiosity. She questioned in her journal why Stanforth would keep any clandestine [[ONI Section Three|Section Three]] medical experiments from her. To her irritation, inquiries she made on the matter were met with dead ends.{{Ref/Reuse|HJ22051}} The facility returned by February 27 and Vice Admiral [[Ysionris Jeromi|Jeromi]] even invited Halsey to come aboard for a look at its new [[Flash cloning|flash-clone organ]] facility.<ref name="HJ22751">''[[Dr. Halsey's personal journal]]'', ''February 27, 2551''</ref> Once they were together he abruptly steered their conversation to tell her he knew she was "fishing" before she could even ask him anything related to the ship's short absence. He also claimed that he knew very little himself and couldn't tell her what he did know, under threat of death.{{Ref/Reuse|HJ22751}}

By [[2551#May|May 2551]] Catherine had begun to lead the excavation of an ancient [[Forerunner|alien]] [[Babd Catha Forerunner vessel|vessel]] that lay [[Babd Catha Forerunner complex|buried]] beneath the area occupied by ONI's [[SWORD Base]] within the [[Babd Catha Ice Shelf]] in northern [[Eposz]].{{Ref/Reuse|DD3}}<ref name="DD2">[[Data Drop]] [[Data Drop/Two|#2]]</ref><ref name="HRTP">''[[Halo: Reach]]'', ''[[The Package]]''</ref> Even so, her residence remained in [[Csongrád]] where she also continued to work with Doctor Sorvad on the Visegrád findings.{{Ref/Reuse|DD3}} On May 8 she was interviewed by analyst [[B.M. Parkes]] so that they might conduct a [[Hemley and Aubourn Behavior Analysis|Hemley and Aubourn behavior analysis]] of her.{{Ref/Reuse|DD3}} Following the encounter Parkes recorded that she had not been terribly forthcoming and ultimately recommended assigning two to three handlers to her at both sites where she was working. Parkes also was confident she needed to be surveilled were she to be called off-planet, though her leaving Reach was something they and their colleagues strongly discouraged at that time.{{Ref/Reuse|DD3}} Two days later Halsey noted in her journal that a security issue which she blamed Sorvad for had caused her to begin keeping an eye on the inhabitants of [[Visegrád]] to ensure they didn't disappear thanks to Section Three.{{Ref/Reuse|HJ51051}} As an insurance policy, she told Stanforth that the people there for valuable for being the only ones with extended exposure to the site under study and as such may need to be studied. She met with Sorvad and he assured her that only certain members of the dig team and a few other "necessary parties" on her side had seen the items recovered from the site. He insisted on continuing the work with only a skeleton crew of his most trusted people and promised he would not tolerate "another [[Farragut Station]]", referring to the communications outpost. Halsey simply nodded but was displeased, wondering if Sorvad might actually know what had happened at Farragut Station in the past and the reason for its relocation.{{Ref/Reuse|HJ51051}} On [[2552#May|May 15, 2552]] Kalmiya caught a glimpse of several documents in Vice Admiral Stanforth's [[Beta-5 Division|Beta-5]] server which ranged from service order transfers of existing Spartan-IIs to highly classified non-Spartan-II detachments.<ref name="HJ51551">''[[Dr. Halsey's personal journal]]'', ''May 15, 2552''</ref> This had evidently been going on for years, and Halsey was incensed at having been kept in the dark about it. She resolved to not let this go, and as she had a list of names with [[James Ackerson|one man]] she considered particularly obscene at the top, she planned to send Kalmiya back in as soon as she got a handle on the affairs with Sorvad.{{Ref/Reuse|HJ51551}} At various points during her time spent beneath the Babd Catha shelf Doctor Halsey kept tabs on a number of individuals and groups, recording her thoughts on each.{{Ref/Reuse|HRTR}} She noted, for example, that she felt inspired by and grateful for those among the [[Seventh Column]] community who had been willing to reach out to her. Halsey was similarly comforted by those involved with the initiatives "[[Fight the Flood]]" and "[[Be a Hero]]". Other civilians which merited her attention during this period included those of [[Red vs. Blue|RvB]] and [[Halo.bungie.org|HBO]], the former having entertained her on multiple occasions and the latter impressing her enough to make her consider providing the faction with direct access to her internal systems. When the doctor initially caught wind of a training protocol which had seen [[Randall Glass|a]] marine [[Warthog jumping|lift]] an [[M12 Warthog]] with [[M9 fragmentation grenade|grenades]], she did not believe the reports. Upon seeing video footage of the accomplishment, however, she decided to flag his file for investigation. It was her opinion that though he should be recommended for the ODSTs, it was too risky to keep him in the field and run the risk of others emulating his foolish actions. And finally, Catherine took care to recognize [[HCFS]], which represented her eyes and ears in the field. At some point during this time she worried she might have a security breach, as a file in her workspace had been opened which she could not recall ever accessing.<ref name="HRTR">''[[Halo: Reach]]'' "[[Tribute Room]]"</ref>

===NOBLE Team===

{{Quote|All the pieces are almost in place for [[Operation: RED FLAG]]. My [[NOBLE Team|curiosity]], for once, must wait. If one small team of Covenant have infiltrated Reach, more will certainly follow. I must prepare for the worst-case scenario with [[Operation: WHITE GLOVE|WHITE GLOVE]].|Catherine, writing in her journal, puts aside her confusion concerning the Spartans of NOBLE Team in order to focus on more pressing matters.}}<ref name="HJ72652">''[[Dr. Halsey's personal journal]]'', ''July 26, 2552''</ref>

[[File:Jorge Deployment Details.jpg|thumb|left|250px|Halsey's attempt to access restricted information concerning Jorge-052 prompted a personal message being sent to her from [[Colonel]] [[Urban Holland]], who had operational control of NOBLE Team.<ref name="HJextras">''[[Dr. Halsey's personal journal]]'', additional materials</ref><ref name="HRNobleA">''[[Halo: Reach]]'', ''[[Noble Actual]]''</ref>]]

The data in Sorvad's last message to her had been compromised along with the entire relay hub, which had been effectively destroyed.{{Ref/Reuse|HJ72652}} Following her meeting with NOBLE Team Halsey noted in her journal that security measures were under way to preserve ONI's discoveries in the [[Viery Territory]] and to integrate and update [[Cortana]] with the latest intelligence from the [[Visegrád]] site. In addition, she was able to confirm definitely that the five with Jorge were indeed Spartans. She pulled Jorge's service record, but more was redacted than was usual even for a Spartan and she had trouble reconciling his recent activity with [[Naval Special Weapons]]. Seeing how he had seemed to grow in the past two decades, she made a note to herself to check [[Wikipedia:Pituitary gland|pituitary]] and [[Wikipedia:Human growth hormone|human growth hormone]] levels for enduring catalytic side effects. Halsey figured Jorge must be glad to be back on Reach, even given the circumstances, but was unsure whether or not she was only displacing or projecting her own feelings onto him. The others on NOBLE Team, of course, were a mystery to her, but seeing them did remind her once more that Mendez was missing. If time had permitted, she would have pursued this thread, but as all the pieces for [[Operation: RED FLAG]] were almost in place, she had to wait. The Covenant's presence on Reach was also enough to get her to begin preparing for [[Operation: WHITE GLOVE]], which involved denying the enemy access to classified data.{{Ref/Reuse|HJ72652}}  

===The artifact from Sigma Octanus IV===

{{Quote|From this supplemental data (which I couldn't copy and had to replicate from memory), I've hypothesized that the language/code, and hence the object, derives from predecessors of the Covenant, or from an unknown, more ancient alien culture. Deciphering the message on the object, however, eludes me for the moment. A more definitive analysis certainly requires the actual object and all relevant etiological data. I only shared this with my undisclosed ONI counterparts because I knew it would get back to Ackerson and "inform" him that he possesses an authentic alien artifact... One that he would need ''me'' to decipher. If so, I'll get everything he has.|Catherine muses in her journal about how best to get more information on the Sigma Octanus IV findings.}}{{Ref/Reuse|HJ82452}}

[[Battle Group Leviathan]] arrived at [[Reach]] from [[Sigma Octanus IV]] by [[2552#August|August 12]] so Halsey went on that date to see what had been done to her [[Mjolnir]] units.<ref name="HJ81252">''[[Dr. Halsey's personal journal]]'', ''August 12, 2552''</ref> Replacement parts and possible upgrades were available, though she noted later that day that [[John-117]] would need to be laser scanned for the new cybernetic implants she planned to give him. Once she was aboard his {{Class|Halberd|light destroyer}}, the {{UNSCShip|Iriquois}}, [[Jacob Keyes]] came to see her as she had been both hoping and dreading.{{Ref/Reuse|HJ81252}} They were able to talk about Miranda, his recent "[[Keyes Loop]]", the Spartans (including their operational records, which she showed him), and what little she could prematurely disclose about [[Operation: RED FLAG]].{{Ref/Reuse|HJ81252}}<ref name="HTFOR29">''[[Halo: The Fall of Reach]]'', ''Chapter 29''</ref> When they parted they wished one another the best on their respective missions and Keyes even kissed her on the cheek when she offered her hand to shake.{{Ref/Reuse|HJ81252}} By 1100 hours later that day she was present for Keyes' debriefing at [[Camp Hathcock]], sitting on a panel which included herself, Admiral Stanforth, and [[Colonel]] [[James Ackerson]].<ref name="HFORI">''[[Halo: Fall of Reach]]'', ''[[Halo: Fall of Reach - Invasion|Invasion]]''</ref> A little over ten minutes later she met John within one of the camp's military complexes—where he had just finished his own debriefing.<ref name="HTFOR24">''[[Halo: The Fall of Reach]]'', ''Chapter 24''</ref> She was sitting in an overstuffed chair when he returned to the debriefing lounge and her surprise presence caught him off guard.{{Ref/Reuse|HTFOR24}} She asked how he was doing, making sure to not give any suggestion that [[Battle at Szurdok Ridge|all was not well]] on Reach at that moment, as it had been decided the Spartans should be kept in the dark for the time being so that RED FLAG might not be compromised.<ref name="DD5">[[Data Drop]] [[Data Drop/Five|#5]]</ref>{{Ref/Reuse|HTFOR24}} In the few minutes they had Halsey told him about the upcoming procedures planned for him and gave his head a cursory [[Wikipedia:Magnetic Resonance Imaging|MRI]].{{Ref/Reuse|HJ81252}} John asked after [[Franklin Mendez|Mendez]] and all the others the two of them had called family and Halsey shared what little she knew without giving heed to protocols or security clearances. They then sat together quietly for a time.{{Ref/Reuse|HJ81252}} John was enthusiastic about the victory at [[Sigma Octanus system|Sigma Octanus]], so she asked whether he would like another victory and perhaps the biggest they'd ever had at that.{{Ref/Reuse|HTFOR24}} She left things with him there, however, and just offered that they'd be speaking soon. Turning to the [[military police]] attendant waiting at the lounge's entrance, she instructed him to open the doors so she could take her turn speaking to the committee of twelve naval officers, ONI and otherwise.{{Ref/Reuse|HTFOR24}} Two days later Halsey was within [[SWORD Base]] again when it saw further bombardment from the [[Covenant]].<ref>''[[Halo: Reach]]'', ''[[Long Night of Solace (level)|Long Night of Solace]]''</ref> On [[2552#August|August 23]] the Spartans of [[NOBLE Team]] were informed they were to redeploy to SWORD Base for a torch-and-burn operation meant to keep Doctor Halsey's excavation data from falling into enemy hands.{{Ref/Reuse|HRNA}} Unbeknownst to them, they were actually being recalled there so the doctor could use them as couriers for the fragment of Cortana which would need to be reunited with the rest of her before the ''Pillar of Autumn'' departed.{{Ref/Reuse|HRTP}} At some point prior to their eventual arrival on August 30, while within her lab at Babd Catha Catherine reviewed what she knew about the team's members with Cortana, seeing as one of them would need to personally take possession of the fragment for delivery.{{Ref/Reuse|HRTP}}{{Ref/Reuse|ASWR}}{{Ref/Reuse|HJ83052}} Cortana elected to give that role to [[Spartan-B312]], the team's newest member—a decision Halsey agreed with.<ref name="ASWR">''[[Halo: Reach ViDoc: A Spartan Will Rise|A Spartan will Rise]]''</ref>

In order to pull RED FLAG off, it had been determined that a colony of significant value to the Covenant and boasting many [[Forerunner|ancient alien]] artifacts would in all likelihood need to be sacrificed in order to draw the required Class-Five assets, possibly with hierarchs, in so that Spartans could infiltrate them. The best shot at taking over a large ship would come after a fleet believed it had secured a major victory.{{Ref/Reuse|DD5}} Given the current situation on Reach, ONI had decided to make the most of a losing fight and enact RED FLAG there. It was for this reason that not one of the twenty-five Spartans was yet aware that [[Reach]] was already [[Fall of Reach|under siege]], largely thanks to the efforts of Halsey and Stanforth, who had been making sure to keep them well away from the primary target sites.{{Ref/Reuse|DD5}} Later that day Halsey reflected on the meeting in her journal, being hopeful for the Spartans' ability to secure a temporary peace that would but humanity time.{{Ref/Reuse|HJ82752}} She expressed her thrill at seeing so many of them together once again and mourned for those who had died years past, truly surprised at how emotional the gathering had made her. She was confident they were ready, but still resolved to appear strong for their benefit. She noted that the [[MJOLNIR Powered Assault Armor/Mark V|Mark V]] armor they'd soon be gifted with was one small operation and a few tests from completion. With only a few days left before she expected to learn whether all her discoveries and sacrifices had been worth it, she closed that day's entry wishing there was time to properly analyze her feelings and reminding herself that four small tasks still remained to complete.<ref name="HJ82752">''[[Dr. Halsey's personal journal]]'', ''August 27, 2552''</ref> By this point she had begun splitting Cortana into separate programs in order to juggle the [[Visegrád]] findings with RED FLAG.{{Ref/Reuse|DD5}} Cortana, for her part, was continually updating her separated portion and would keep doing so until the last possible moment. Catherine was excited to see how she and John took to one another.{{Ref/Reuse|HJ82752}} She had assured Stanforth that Cortana remained fully functional even with a large portion of her processes excised.{{Ref/Reuse|DD5}}

By 0600 hours on August 29 Catherine and others were waiting for John at the "Prep and Recovery" area of [[Military Reservation 01478-B]].<ref name="HTFOR27">''[[Halo: The Fall of Reach]]'', ''Chapter 27''</ref> She entered a prefabricated structure there just as the Spartan was having the back of his neck swabbed to tell him it would only take a moment to upgrade a few components of his [[neural interface]].{{Ref/Reuse|HTFOR27}} She asked him to lie back and remain still, and once the procedure began she assisted to some degree with fusion of the new components.{{Ref/Reuse|HTFOR27}}<ref name="HJ82952">''[[Dr. Halsey's personal journal]]'', ''August 29, 2552''</ref> She took a brief moment to note in her [[Dr. Halsey's personal journal|journal]] that the surgery had gone flawlessly and that his recovery would be well within regenerative parameters.{{Ref/Reuse|HJ82952}} At that moment tests to evaluate the integration of the [[MJOLNIR Powered Assault Armor/Mark V|Mark V]] Mjolnir and A.I. were planned to commence in around three hours.{{Ref/Reuse|HJ82952}} Once John was finished receiving his upgrades she asked him to follow her to a field command dome on the reservation's range.{{Ref/Reuse|HTFOR27}} After presenting her credentials to the [[military police]] standing guard and submitting to identification scans she led John in to introduce him to the Mark V armor.{{Ref/Reuse|HTFOR27}} Halsey asked him to put it on, averting her eyes as he did so with assistance from two technicians. She explained hundreds of minor technical improvements had been made compared to the [[MJOLNIR Powered Assault Armor/Mark IV|Mark IV]] and that she would send the specifications to him later. The two most significant additions, she added, were the armor's [[energy shield]] system and a weave of memory-processor super-conductor which allowed it to carry an A.I. She taught him how to adjust the shielding and assured him he'd get to see how much punishment it could take soon (she herself had suggested live rounds for the upcoming testing) before finally introducing him to [[Cortana]].{{Ref/Reuse|HTFOR27}}{{Ref/Reuse|HTFOR28}} The A.I. had been provided with the very best [[Sangheili (language)|Covenant language]] [[translation software]], Halsey said, so that she could infiltrate their computer and communications systems. Halsey promised Cortana would not be able to control his armor when John asked, though she would improve his reaction time. It was her explanation that, like him, Cortana would do whatever was necessary to complete [[Operation: RED FLAG|their mission]] that relieved the Master Chief. He knelt so Halsey could insert her [[Data crystal chip|memory processor matrix]] into his helmet and then watched with great interest as the Spartan and A.I. met one another for the first time.{{Ref/Reuse|HTFOR27}}

[[File:Halsey n' Six.jpg|thumb|350px|left|Halsey hands Cortana's fragment to SPARTAN-B312.]]

Doctor Halsey entered her [[SWORD Base]] office shortly after 0400 hours on August 30.<ref name="HTFOR28">''[[Halo: The Fall of Reach]]'', ''Chapter 28''</ref> At checkpoint three she was briefly [[Cortana|delayed]] by a reset of the verification system, which required her to speak that day's code phrase and undergo a retina scan twice in order to proceed. Unbeknownst to her, these interruptions were caused by Cortana, who the doctor had wrongly thought she could keep occupied at that moment with checking the systems on the ''Pillar of Autumn''.{{Ref/Reuse|HTFOR28}} The doctor had sent an official protest against Ackerson to the {{UNSCShip|Burden of Proof}}, backed by Admiral Stanforth, but was still tracking his possible involvement with the missile incident from the previous day.<ref name="HJ83052">''[[Dr. Halsey's personal journal]]'', ''August 30, 2552''</ref> She had also suggested he may have suffered a mental breakdown and advised he be taken into custody, pending evaluation. She had received reports of either he or his agents investigating the area around [[CASTLE Base]]'s [[Xenoarchaeology|xenoarcheological]] site in addition to scattered ones which alleged increased [[Covenant]] activity in the vicinity as well. In her journal, she surmised that Ackerson was unlikely to find anything of interest there and cynically expressed hope that he might cross paths with the enemy. Before NOBLE Team's arrival Catherine had a number of tasks which she was determined to make sure were accomplished. She prepared [[Kalmiya]], finalized and compiled a firmware update for the part of [[Cortana]] which remained with her and upgraded that [[Armored matrix|package]] for transfer, sent a note to Miranda by way of the {{UNSCShip|Hopeful}}, enabled a network purge, and prepared all backups for an Umbra slipspace shot to Earth. The reports Halsey had seen made her confident Reach was surely lost, but having completed what she'd needed to she felt prepared in her lab as she waited for the Spartans.{{Ref/Reuse|HJ83052}} [[NOBLE Team]] had arrived outside SWORD Base by 2616 hours on August 29 (local time).{{Ref/Reuse|HRTP}} Shortly before the team reached Doctor Halsey [[Jerrod]] let her know SWORD Base's perimeter had been compromised, despite assertions to the contrary being made by the base's own A.I. In case something were to happen to her, Halsey recorded a purge code and its override failsafe password in her journal.{{Ref/Reuse|HJ83052}} At some point prior to the Spartans' arrival Halsey was one of only three friendly personnel registering with the base's security system.<ref name="HRG">''[[Halo: Reach]]'', ''[[Glacier (Halo: Reach map)|Glacier]]''</ref>

Upon entering SWORD Base the surviving members of NOBLE were led at [[Cortana]]'s direction to a tram which would carry them one-and-a-half kilometers east and around two thousand feet underground, where Halsey's laboratory was.{{Ref/Reuse|HRTP}} Once the four of them had climbed aboard she appeared on a monitor and apologized to [[Carter-A259]] for the unusual security measures which had kept them from fully knowing what to expect at the base. He started to remark on the fact that she'd been listed as having died, but the doctor dismissed the casualty reports relating to her as false before he could finish and said she only wished the same could be said for the rest of his team, both [[Jorge-052]] and [[Catherine-B320]] having been killed within the last few weeks. She offered what might have been a small comfort in sharing that the [[data module]] delivered by Kat had unlocked the secrets of her nearby [[Babd Catha Forerunner vessel|excavation]]. She then explained that their orders to destroy all sensitive material at the base had been overridden, as they had always been nothing more than a pretext to bring them to her so that they could take possession of this vital data and deliver it elsewhere. Carter argued that he would need to confirm this change with Colonel [[Urban Holland|Holland]], but Halsey assured him he would be briefed and said that they belonged to [[ONI]] now. As soon as NOBLE team first laid eyes on the [[Babd Catha Forerunner vessel|massive ship]] Halsey explained that it was [[Forerunner|alien]] but not Covenant in origin and that thanks to Kat's data its decryption was nearly complete. Carter urged her to have it ready when they reached her but the doctor insisted the decryption was still underway and, should they allow any of it to be left buried there, they'd be burying [[Human|mankind]]'s [[Installation 04|best chance]] for survival. Covenant attackers soon began encroaching on her lab and she implored the Spartans to defend it in order to buy her all they time they could. As NOBLE Team fought off successive waves of enemies Halsey occasionally updated them on the progress of the data's final decryption, and as soon as it was complete she let them know she was opening the laboratory's door. Within, she explained to them that [[Cortana]] was the important data's custodian and had been the one to choose them as her couriers. [[Emile-A239]] found the notion strange, and at that Halsey made it known that ''this'' A.I. was special. She then told them they were to carry her to the [[Asźod ship breaking yards|ship-breaking yards]] in [[Asźod]], where they would find the {{Class|Halcyon|light cruiser}} {{UNSCShip|Pillar of Autumn}} waiting to spirit her away. Carter indicated his understanding of the mission, but Halsey made sure he understood the importance of it, claiming that humanity's annihilation was all but certain unless they could gleam some way to stop the Covenant from the information the ancient ship had provided.{{Ref/Reuse|HRTP}} Once she'd received Cortana's permission to do so, she took her offline so she could be transferred to an [[armored matrix]].{{Ref/Reuse|HRTR}} With that, she removed it from where it had been plugged in and handed it to [[SPARTAN-B312]].{{Ref/Reuse|HRTP}} She said that Cortana had chosen him specifically to carry her and made him confirm he'd taken secure possession of the matrix before finally letting go.{{Ref/Reuse|HRTP}}

===Escape from Reach===

{{Main|Raid on Reach}}

{{Quote|I'm tired of sacrificing others for the 'greater good'. It never stops, Cortana... and we're running out of people to sacrifice.|Halsey to [[Cortana]] before her departure to [[Onyx]].<ref>'''Halo: First Strike''', ''page 298'' (2010)</ref>}}

===Onyx===

{{Main|Onyx Conflict}}

Dr. Halsey and Kelly eventually arrived at [[Onyx]], where they reunited with [[Senior Chief Petty Officer|SCPO]] Mendez and eventually the remaining Spartan-IIs and the [[Spartan-III]]s, under attack by [[Onyx Sentinel]]s. Contacting the ONI AI [[Endless Summer]], she utilized Onyx's [[slipspace COM launcher]] and Cortana's slipspace transmission from [[Installation 05]] as a carrier wave to send a message to Earth, in which she requested [[Terrence Hood|Lord Hood]] to send more Spartans to secure Forerunner technology on Onyx. Her relative expertise with Forerunner technology was vital to the survival of the UNSC forces on the planet, as she was able to interpret Forerunner glyphs when navigating the facility, guiding the Spartans to a [[Cartographer|map room]], where Onyx was revealed to be a wholly artificial construct. She also learned how to employ the local [[teleportation grid|translocation grid]], allowing the humans to move across the megastructure while evading the [[Joyous Exultation Covenant|Covenant]] forces that pursued them.

===Requiem===

{{Quote|Life is too short. I will never learn all that exists in our own tiny galaxy, let alone the rest of the universe. And I so desperately want to know ''everything''. But the UNSC acts like children at play in a sandbox. Mistaking its edges for the limits of the world.|Catherine Halsey to Captain Thomas Lasky regarding her subterfuge.}}

[[File:H4-SO Halsey discover John' status.jpg|left|thumb|250px|Halsey discovering John-117 is alive.]]

Late in the attack, Halsey was kidnapped by a Promethean Knight and teleported to Requiem. When Admiral Serin Osman was informed of this abduction, she chose to finally enact Parangosky's wishes and ordered for Halsey's immediate termination. While Captain Lasky protested against this, instead sending Fireteam Majestic to rescue Halsey, Commander Palmer departed to carry out Osman's order.<ref name="Spops8">'''Spartan Ops''', [[S1/Expendable|S1E8 ''Expendable'']]</ref>

Halsey was then taken to the [[Librarian's Rest]], where Jul 'Mdama had her disable the shield previously erected during Doctor Glassman's attempts to access the shrine. As the shield deactivated, she quickly entered the beam of light being produced by the shrine, to 'Mdama's great anger.{{Ref/Reuse|Spops8}} There, she met the Librarian and was given the [[Janus Key]], which gave the location of every Forerunner artifact in the galaxy. After taking the key, Halsey was returned to the shrine, where 'Mdama acquired one half of the artifact. The intervention of Palmer and Fireteam Majestic forced 'Mdama to retreat from the site with Halsey, but not before she threw the key's other half to Thorne. During the firefight, however, Palmer managed to shoot Halsey in the shoulder.<ref name="s1key">''[[Spartan Ops]]'': [[S1/Key|S1E9 ''Key'']]</ref>

}}

[[File:HE14 Plan.jpg|thumb|250px|left|Halsey and 'Mdama plot against the UNSC.]]

At Halsey's suggestion, 'Mdama had a fake Forerunner artifact placed in a Forerunner structure on the nearby [[Aktis IV]]. As per Halsey's plan, Dr. Glassman and the Spartan-IVs of ''Infinity'' discovered the artifact and believed that it was related to the Janus Key. Halsey and Jul watched Glassman's investigation from ''Song of Retribution'' and Halsey revealed that she knew Jul's public persona was a mere façade when 'Mdama expressed mock abhorrence at creating a copy of a "holy" Forerunner object. Meanwhile, Glassman requested for ''Infinity'' to deliver their half of the Janus Key to him on the planet's surface for further analysis. Anticipating this, Halsey ensured that 'Mdama had troops ready to ambush the UNSC convoy carrying their half of the Key. Much to both Halsey's and 'Mdama's surprise, the Pelican carrying the half was shot down before he could give an order. In the confusion, the rest of the Covenant ambush group began the attack. Halsey insisted on personally searching the crash-site, but 'Mdama decided to scourge the crash-site himself, and he ordered Halsey to remain aboard his carrier. Unbeknownst to him, rebel [[Sali 'Nyon]] was responsible for shooting down the Pelican and he claimed half of the Janus Key for himself.<ref name="HE14">'''Halo: Escalation''', ''[[Halo: Escalation Issue 14|Issue #14]]''</ref>

Shortly after, Jul's forces fled the system with both halves of the Janus Key. Halsey and Jul used the combined Janus Key to project a holographic map, which revealed the approximate location of the [[Absolute Record]].{{Ref/Reuse|HE16}} Hiding within the [[Urs system]], Halsey worked on finding the coordinates of the Absolute Record, on [[2558#September|September 15, 2558]] pinpointed its exact location. Two days later, as the fleet prepared to depart for the Absolute Record, a Phantom carrying Spartans Palmer, Thorne, [[Holly Tanaka]], Dr. Glassman, and [[Ayit 'Sevi]]—a mercenary within 'Mdama's ranks working for ONI—boarded ''[[Breath of Annihilation]]'', intent on revealing the location of the Absolute Record to the UNSC.

The fleet arrived at an apparently artificial gas giant with a slipspace portal leading to the Absolute Record. Before the fleet could press forward, slipspace ruptures materialized around the fleet, destroying at least two ships and damaging ''Breath of Annihilation''.<ref name="HE19">'''Halo: Escalation''', ''[[Halo: Escalation Issue 19|Issue #19]]''</ref>  Furious at the damage done to his fleet, 'Mdama blamed Halsey for the loss and threw her across ''Song of Retribution''<nowiki>'</nowiki>s bridge. While Halsey and 'Mdama argued about the situation, she reminded him that once they reached the Absolute Record, they will discover technology beyond their comprehension that will more than compensate for the ships that were destroyed. Halsey further exaggerated that once he was in control of the Absolute Record's "treasures", 'Mdama would be seen as a god. Thus 'Mdama decided to travel to the Absolute Record, with only ''Retribution'' entering the portal while the rest made repairs. As Halsey and 'Mdama prepared to enter the portal, they learned of rumors of the Spartans attacking personnel of ''Breath of Annihilation''. Halsey dismissed 'Mdama's fears and stated that the Spartans could not stop them from reaching the Absolute Record, though she was unaware that Palmer, Tanaka, and Glassman had boarded ''Retribution''.  

In order to decide who would be the legitimate steward of the Absolute Record, the AI decided on a direct examination. It had both factions isolated and gave them a hypothetical scenario, in which a sapient species (represented by [[Yonhet]]) turned out to have bodies conducive to a Flood vaccine. Abducting and harvesting live beings would give a thirty-five percent chance of Flood-immune material, but receiving dead bodies from the beings would give them a thirty-three percent chance. Despite Jul's advice, Halsey chose live capture while Glassman chose the peaceful option, and the ancilla commended both. It then asked if their opponents in this test should be kept confined or immediately killed, but instead of answering, Halsey hacked the ancilla and shut it down, taking control of the Record for herself.<ref name="HE22">'''Halo: Escalation''' ''[[Halo: Escalation Issue 22|Issue #22]]''</ref>

===The Guardians===

{{Quote|I tried to warn you this was happening. Cortana is no longer an asset, Captain. She is a danger.|Halsey stresses the enormity of the threat posed by Cortana to Captain [[Thomas Lasky]].}}{{Ref/Reuse|H5GG}}

Near the end of September Doctor Halsey managed to contact ONI and the {{UNSCShip|Infinity}} and provide Captain Lasky with coordinates at which she could be found.{{Ref/Reuse|HBB1}}<ref name="H5GO">''[[Halo 5: Guardians]]'', ''[[Osiris (level)|Osiris]]''</ref> They pointed to the planet [[Kamchatka]] in the [[Caspar system]], where a [[Forerunner]] communication hub had recently flared to life and attracted the attention of both [[Jul 'Mdama|Jul]] and the [[UNSC]].{{Ref/Reuse|H5GO}}<ref name="WaypointKamchatka">[https://www.halowaypoint.com/en-us/universe/locations/kamchatka '''Halo Waypoint''' - ''Kamchatka'']</ref> Upon reaching Kamchatka Halsey set about studying the nature of various incoming signals which were bouncing off of the Forerunner objects on the planet, akin to echolocation.<ref name="H5GOMI">''[[Halo 5: Guardians]]'', ''[[Osiris (level)|Osiris]]'' [[Mission Intel#Osiris|mission intel]]</ref> Halsey concluded that [[Cortana]] was searching for [[Guardian Custode|something]] but could not guess at what that something might be. At Halsey's direction, a structure that was the focal point for one of the signals was eventually penetrated by the [[Jul 'Mdama's Covenant|Covenant]] forces with her. In her research notes Halsey bemoaned the way in which her work was being hampered by their overriding concern for ceremony, leaving her still without much information she did not have before they breached the structure. Some time later, however, Halsey obtained scans of new [[Forerunner symbols|glyph]]s, including one that she was sure had never been observed before. After running it through a system she found that it bore a resemblance to an ancient [[Sangheili]] symbol for a [[Sangheili mythology|demon]] that sleeps in the ground and must not wake. How this symbol might relate to the symbol, she was still unsure. Halsey further noted that the readings she would expect from a Forerunner structure the scale of which they inhabited were erratic at best, leading her to then wonder if perhaps Cortana was trying to access technology on Kamchatka and other locations directly, but failing.{{Ref/Reuse|H5GOMI}}  

{{Quote|I'm playing along with your protocol here, Thel. If the [[SPARTAN-IV program|fours]] bring me an active Constructor, I can interface with the Guardian. It will receive Cortana's signal the moment it activates and initiates slipspace, but I think I can make sure it leaves the sea before it jumps. I'll get it in the skies over Sunaion, like you asked.|Catherine records a message for Thel 'Vadam, the Sangheili Arbiter.}}{{Ref/Reuse|H5GAMI}}

After arriving in the [[Urs system|Urs-Fied-Joori system]] on [[2558#October|October 27]] Halsey accompanied [[Sarah Palmer|Palmer]] to a waiting [[D79-TC Pelican]] in the process of being loaded up for travel to [[Sanghelios]].{{Ref/Reuse|H5GSOS}} At the approach of Spartans [[Jameson Locke|Locke]] and [[Olympia Vale]] Palmer let it be known that the doctor was trying to find a way to communicate with the [[Guardian Custode]] on the planet. Halsey assured Locke she'd have a briefing for him once they were all planetside.<ref name="H5GSOS">''[[Halo 5: Guardians]]'', ''[[Swords of Sanghelios (level)|Swords of Sanghelios]]''</ref> [[Fireteam Osiris]] soon met up with [[Thel 'Vadam|the Arbiter]] and following this Halsey and Palmer joined them at a camp the [[Swords of Sanghelios]] had set up in [[Nuusra]].<ref name="H5GA">''[[Halo 5: Guardians]]'', ''[[Alliance]]''</ref> Whilst Locke was treating with 'Vadam, [[Cortana]]'s voice suddenly rang out from within their meeting tent, prompting Halsey and Palmer to both rush inside. Halsey noted that she'd touched every networked device in the camp just then and concluded she must know of the Guardian they were after. 'Vadam agreed to assist in the effort to get to it at [[Sunaion]] but only on the condition that victory would be assured when they finally moved on the city. Pledging they'd deploy within the hour, Locke told Halsey to have her plan ready by then.{{Ref/Reuse|H5GA}}

While she continued to devise a strategy Halsey recorded a status update for the [[Arbiter]], [[Thel 'Vadam]], in which she assured him the Guardian would be in the sky over Sunaion before it initiated a [[slipspace]] jump, as he had asked.<ref name="H5GAMI">''[[Halo 5: Guardians]]'', ''[[Alliance]]'' [[Mission Intel#Alliance|mission intel]]</ref> In return for her cooperation with his request she also made one of her own for more intelligent assistants to aid her and urged him to loosen the security placed on her.{{Ref/Reuse|H5GAMI}} Sometime after this she contacted Locke over an open communications channel to let him know she'd prepared the briefing but preferred to discuss it in person to avoid being eavesdropped upon.{{Ref/Reuse|H5GA}} From atop a [[Forerunner]]-built structure overlooking the camp she waved the Spartans over to her as they neared and then proceeded to introduce them to what a [[Constructor]] [[sentinel]] was. She explained that if one could be acquired from the support stations which riddled the hills around them then she could use it to interface with the Guardian. She further informed them that Palmer had the location of one such station.{{Ref/Reuse|H5GA}} In a supplemental status update for Thel, she pointed out that while making stubborn claims to not need her or the Guardian he ought to remember the [[ONI|organization]] she represented and its history.<ref name="H5GBTSMI">''[[Halo 5: Guardians]]'', ''[[Before the Storm]]'' [[Mission Intel#Before the Storm|mission intel]]</ref> She hoped that this would get him to show her some respect and signed off by claiming this was to be her last mandatory update.{{Ref/Reuse|H5GBTSMI}} Osiris secured a Constructor before the suns had set and returned to the camp with it.<ref name="H5GBTS">''[[Halo 5: Guardians]]'', ''[[Before the Storm]]''</ref> Halsey observed that it seemed to be working as she had planned for it to but told Locke's team that it could take some time until she was finished calibrating it. She then let them know that Palmer wished to see them. When she was ready, she called Osiris back over to her spot on the Forerunner structure, which she informed them she was using to upload the coordinates recorded on [[Meridian]] into the sentinel. She wanted them to be ready to go as soon as she signaled it was time but admitted it might before hours until then. However, the Constructor suddenly took off just then, flying toward Sunaion. As Osiris and the Swords of Sanghelios prepared to follow it Halsey made sure Locke knew Cortana had been built from a matrix of her own mind, cautioning him that like her, she would take drastic measures if she thought they served the greater good. The [[Domain]], she added, would give her incredible power with which to enact those measures. As Locke walked away she called out to him again and pleaded with him to stop Cortana but to bring [[John-117|John]] home to her.{{Ref/Reuse|H5GBTS}}

===On the run===

A little less than an hour before sunrise the next day the Spartans and Halsey all piled into the Pelican.{{Ref/Reuse|HBB1}} As the Arbiter bid farewell to John and voiced his confidence in their ability to combat the new threat the [[Created]] posed, the Sangheili shot Halsey a meaningful glance which she ignored with a haughty sniff. While ''en route'' to the rendezvous Halsey pointed out that Sangheili resistance was likely drawing the attention of the [[Guardian]] attempting to pacify the world just then, again arguing that they'd already be dead if they'd been detected. With about twenty minutes until the ''Infinity'' was due to arrive Buck broke out a pack of playing cards and asked if anyone was up for [[Wikipedia:Hearts|Hearts]] but Halsey ignored him, as she was working on a tablet she'd scrounged up. Buck managed to get her attention by referring to the [[Wikipedia:Queen of spades|queen of spades]] as a "Halsey" a couple of hands into the game, but she still gave no response other than to announce that their window was approaching. The gargantuan [[Infinity-class supercarrier|supercarrier]] arrived almost exactly on schedule and Halsey had secured all her things by then. As Kelly docked the Pelican in the ship's Portside Bay Five Buck drew Halsey's attention yet again when he laughed out loud upon realizing his longtime lover [[Veronica Dare]] was aboard.{{Ref/Reuse|HBB1}} The doctor and the Spartans were met in the bay by a lieutenant who had come to escort she, Palmer, John, and Locke to the bridge to see Captain [[Thomas Lasky|Lasky]].<ref name="HBB2">''[[Halo: Bad Blood]]'', ''Chapter 2''</ref> Following that meeting Lasky had Doctor Halsey confined to a workspace and the ''Infinity'' began a series of randomized [[slipspace]] jumps in order to avoid detection by Cortana's [[Guardian Custode|Guardian]]s, emerging from slipspace at its first vector point that very day.<ref name="lootcrate12">''[[Halo Legendary Crate]]'' ''[[Halo Legendary Crate/Data Drops|Data Drop #12]]''</ref>{{Ref/Reuse|HBB2}} That same day [[Roland]] answered a distress call from the {{UNSCShip|Sentry of El Morro}} with the affirmation that the supercarrier was on its way to assist it.<ref name="HFRW">''[[Halo: Fractures]]'', ''[[Rossbach's World (story)|Rossbach's World]]''</ref> By the start of November, the ship exited slipspace at one point to receive the recently reassembled Spartan team [[Alpha-Nine]].<ref name="HBB21">''[[Halo: Bad Blood]]'', ''Chapter 21''</ref>{{Ref/Note|The presence of [[031 Exuberant Witness]], [[monitor]] of the [[Builder]] world [[Genesis]], as a [[multiplayer]] announcer in ''[[Halo 5: Guardians]]'', may indicate that the ''Infinity'' also at some point received her. [[343 Industries]] writer [[Jeff Easterling]] has said, however, that Witness' presence on the ship may not be entirely canonical.}}

By [[2559#January|January 24, 2559]], they were still on the run, performing erratic jumps to evade discovery.{{Ref/Reuse|lootcrate12}} That day, at just after 1204 hours, Halsey was approached by a Spartan from [[Fireteam Apollo]] with the serial number [[92738-61842-LC]]. This individual had been tasked by Captain Lasky with investigating what was being dubbed "the Guardian Incident". Halsey pointedly asked how they had gotten clearance to talk with her and was made aware of the priority-one directive given to them by the captain. After then confirming she was being recorded, the Spartan informed her they were there to talk about [[Cortana]]. Halsey was interested to hear what their investigation had unearthed so far, but they reported not being authorized to share anything further than their having concluded that the cognitive duress and strain Cortana had sustained since the discovery of [[Installation 04]] was partially responsible. The Spartan's first questions for the doctor concerned Cortana's creation, and Halsey was soon defending her actions incumbent in that process. She also refused to reveal what had become of the clones of herself she had made, claiming that was still classified even for them. Asked what she thought the best explanation for what had happened was, Halsey recalled Cortana's first words and theorized she was simply doing she had to in order to keep "the game" from ending. Halsey then quoted the Greek philosopher [[Wikipedia:Epictetus|Epictetus]] and suggested Cortana was the answer to his thought experiment regarding the harm in saying "Tomorrow you will die," while kissing one's child. When her interviewer asked what she thought the solution to stopping her was, Catherine ignored the question since she doubted coming up with that would be part of a Spartan's directive and was convinced she'd been locked away for that purpose. 92738-61842-LC countered that she'd been locked up because of her repeated protocol violations, which only led to further argument and  the Spartan finally choosing to take their leave. Before they went, Halsey shared the [[Cortana Letters#First letter|last thing]] Cortana had said to her.{{Ref/Reuse|lootcrate12}} The Spartan asked what her words were supposed to have meant, but Halsey could only say that she had been hoping they were able to explain them to her.{{Ref/Reuse|lootcrate12}}{{Ref/Note|What Halsey indicated Cortana had last said to her is quoted from the first of the [[Cortana letters]], a series of emails produced prior to the release of ''Halo: Combat Evolved''. Whether or not Cortana said the things she did to Halsey prior to her slipping away from [[Eridanus Secundus]] in [[2552]] or at some point after, perhaps following her accessing of the [[Domain]], is unknown.}}.

==Personality and traits==

{{Quote|If people would just share things with me, I could solve all the world's problems.|Dr. Halsey musing to herself over the UNSC withholding data from her.{{Ref/Reuse|invasion}}}}

Immensely intelligent, reclusive and somewhat self-centered, Halsey is almost entirely devoted to her work and the pursuit of knowledge to advance humankind. She has little regard for rules, authority or bureaucracy, in most cases viewing them as little more than obstacles to her work. While her singleminded dedication and seemingly detached personality have led to many perceiving her as devoid of morals or emotions, she has nonetheless shown to care about the few people close to her and has been deeply affected on a personal level by the moral implications of her work.

===SPARTAN-II program and guilt===

{{Quote|Spartans never die? If only that were true.|Catherine Halsey, reflecting her guilt over the SPARTAN-II program.<ref>'''''Halo: First Strike''''', ''page 249''</ref>}}

Dr. Halsey carried extraordinary guilt because of the [[SPARTAN-II program|SPARTAN-II project]], in the feeling that she had exploited the children and destroyed their lives. Although she continued to support the Spartans and gained monumental prestige for her efforts, she also felt responsible for each one who died. She could never bring herself to justify the Spartans' exploitation as a necessary sacrifice.{{Ref/Reuse|fs129}}<ref>'''Halo: First Strike''', ''pages 243-245''</ref>

===Reputation===

{{Quote|no=two

|1=Sarah Palmer

}}

Many of those unfamiliar with the internal dynamics of ONI and the SPARTAN-II program have come to interpret Halsey and her work in a highly negative light. Despite the predominant role of ONI and the UNSC Naval leadership in the conception and execution of the SPARTAN-II program, Dr. Halsey is often perceived as the sole individual responsible, due to her conspicuous position as the project head.<ref>'''Halo: Glasslands''', ''page 178''</ref> Taking advantage of this, ONI prefers to attribute some of the more controversial aspects of the project to their alleged lack of sufficient oversight.<ref>[http://www.neogaf.com/forum/showpost.php?p=96218485&postcount=40 '''NeoGaf:''' ''Was Dr. Halsey justified, ultimately, in creating the Spartan-II program in Halo? — View Single Post''] ([[Frank O'Connor]]: ''"Other even less savory characters are trying to harm her legacy to boost their own careers. And they're doing it by illuminating her prior actions in an ugly way."'')</ref> [[Black-Box]] even privately acknowledges to Serin Osman that the main reason for Halsey's fall from grace is to conceal or minimize the responsibility of the many others who participated in the project.<ref>'''Halo: Mortal Dictata'''</ref>  Although she was responsible for much of the program's scientific basis and harbored no illusions otherwise, Halsey was under ONI's constant supervision and was even repeatedly pressured by Section III to use more inhumane means for faster results.{{Ref/Reuse|for29}} Many have also interpreted her primary motivation as a supposed perverse scientific curiosity, ignoring—or unaware of—her sincere determination to prevent further excessive bloodshed in the Insurrection and her initial naiveté in failing to grasp the full moral ramifications of her work until witnessing it in practice.{{Ref/Reuse|HJ12410}}

====Jacob Keyes====

During her survey travels for the SPARTAN-II candidates, Halsey was required to be supervised by a military official, an order she resented. She ended up choosing then-[[Lieutenant, Junior Grade]] [[Jacob Keyes]]. Halsey had examined his files and found he had refused to testify against one of his instructors despite the teacher's error causing the deaths of 14 students. From this Halsey deduced that Keyes could be trusted to keep a secret, a useful trait in her unethical mission. The two were initially aloof to each other aboard the ''Han'', especially since Keyes did not initially know the purpose of their mission. He eventually realized it, though, and discussed with Halsey about the implications of her project and her decision to tell the child [[Soren-066|Soren]] the truth. By the time they parted after two months working together, Keyes and Halsey were on much more amicable terms, to the point that Halsey began sketching him frequently in her journal and even referred to him as "my lieutenant". For his safety and in thanks, Keyes was reassigned but given a full [[Lieutenant (UNSC)|lieutenant]] commission, at Halsey's request.

====John-117====

{{quote|This boy could be more useful to the UNSC than a fleet of [[UNSC destroyer|destroyer]]s, a thousand [[Lieutenant, Junior Grade|Junior Grade Lieutenants]] -- or even ''me''. In the end, the child may be the only thing that makes ''any'' difference.|Halsey speaking to [[Jacob Keyes|Lt. Jr. Grade Jacob Keyes]], referring to John-117.}}

Halsey had a unique relationship with [[John-117]], compared to the other Spartans. John was the first subject for the Spartan program that she observed, and during then she noted his determination, physical skill, and luck in answering correctly. Halsey told Cortana she considers him the luckiest and best of the Spartans and apparently also finds him attractive on a subconscious level, given her embarrassed reaction to Cortana's comments.<ref>'''Halo: The Fall of Reach''', ''page 236'' (2001)</ref> The doctor was responsible for John's first promotion to Squad Leader as a result of her acknowledging his leadership skills and suggesting it to Mendez. She also had John's full trust, him always doing his best to never undermine her authority.

Halsey kept [[Dr. Halsey's personal journal|a journal]] with her ever since she was eighteen, purchased from a shop on Reach. She used the journal as a medium through which to express her thoughts and concerns, draw sketches, and map out important research notes for approximately forty-two years. It was not Halsey's only journal, since she had a second one for note-taking and also had an encrypted audio journal on her computer, though she sometimes erased its entries soon after recording them.<ref>'''Halo: Fall of Reach''' - ''Bootcamp Issue 1''</ref> Halsey frequently left her first journal lying around buried under papers, and procrastinated on adding some security measures to it to prevent it from being stolen.<ref>'''Dr. Halsey's personal journal''', ''March 18, 2543''</ref> This absent-mindedness eventually backfired on her when she forgot the journal during her escape from [[SWORD Base]]. The journal was later recovered by ONI in [[2553]], and used as evidence to condemn her.

==Non-canon and dubious canon appearances==

===Silver Timeline===

{{Main|Catherine Halsey/Silver}}

{{Expand-section}}

==Production notes==

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*A number of Dr. Halsey's statements are echoed by similar statements by Cortana in the ''Halo'' games. In ''[[Halo: The Fall of Reach]]'', when John-117 explains his plan to board the [[Unrelenting|Covenant ship]] near [[Chi Ceti IV]], Halsey states, ''"One slight error in your trajectory, and you could miss by kilometers"'', to which John replies, ''"I don't miss, ma'am."''<ref>'''Halo: The Fall of Reach''', '' page 120'' (2001)</ref> A strikingly similar exchange occurs in ''[[Halo 2]]'', with Cortana asking, ''"What if you miss?"'' and John responding, ''"I won't"''. Many of Cortana's lines during the [[Cortana moments and Gravemind moments|Cortana moments]] in ''Halo 3'' are direct quotes or slight paraphrases of Halsey's statements to the Spartans in ''Halo: The Fall of Reach''. In ''[[The Package (animated short)|The Package]]'', Halsey tells John-117 that she slept well, ''"No thanks to their driving,"'' which is echoed in ''Halo: Combat Evolved'' when he tells Cortana he slept well ''"... no thanks to [her] driving"''. She also tells John, ''"Don't make a girl a promise if you know you can't keep it,"'' which Cortana would tell him in ''Halo 2''.

*In ''Halo Legends'', Halsey's appearance was portrayed with a great deal of artistic license. In ''The Package'', at which point she is aged fifty-two, she is depicted as a young woman with short, blonde hair and no glasses. Her appearance in ''Homecoming'' however, is closer to her description from the books, though that short also portrays her as blonde. In the developer commentary for ''Homecoming'' [[Frank O'Connor]] states, "''People tend to think of her as older than she's portrayed... and part of that was simply—you know—it's anime, and they want everyone to be attractive and young. I mean, that's one of the hallmarks anime... I think that IG took the safer of the two routes and sort of disguised her appearance and disguised her age by having it literally obscured by her hair and her glasses and to a certain extent her uniform.''" In ''The Package'' commentary he explains, "''She was definitely one of those back-and-forth conversations [with Casio Entertainment]; 'Can you make her older? Can you make her older?' And eventually we got to this compromise... I think if we were casting a real-life actress we'd cast someone a lot older, but in anime the context is fine and it works.'"''

File:HTFOR-Halsey.png|Halsey in ''[[Halo: The Fall of Reach - The Animated Series]]''.

File:H5G-Render-Halsey.png|A render of Halsey in ''Halo 5: Guardians''.

File:HINF HoloHalseyCortana.png|A hologram of Halsey along with Cortana in ''[[Halo Infinite]]''.

</gallery>

*''[[Halo Infinite]]''

*''[[Halo: The Television Series]]''

{{col-end}}