Editing Fireteam Osiris

{{Disambig header|the Spartan-IV team|other uses|Osiris (disambiguation)}}

|size=3 (as of [[2558|November 2558]])

*Spartan [[Jameson Locke]] – Team leader; former acquisitions specialist for the [[Office of Naval Intelligence]].{{Ref/Reuse|universe}}

*Spartan [[Holly Tanaka]] – A highly skilled engineer; former member of the [[UNSC Army]] Corps of Engineering.{{Ref/Reuse|universe}}

*Spartan [[Edward Buck]] – A former [[Orbital Drop Shock Trooper]],{{Ref/Reuse|universe}} and former advisor and mentor of the team.<ref>[http://news.microsoft.com/stories/halo5/ '''Microsoft''': ''Stories - Halo 5'']</ref> After the beginning of the [[Created conflict]], Buck was sent by ONI on a secret mission to [[Cassidy III]] that led him to reform his old team of [[Alpha-Nine]]. Following the mission, Buck chose to leave Osiris to lead Alpha-Nine again on a permanent basis.<ref name="Bad Blood">'''[[Halo: Bad Blood]]'''</ref>

After several human colonies were unexpectedly attacked by mysterious Forerunner entities, Doctor [[Catherine Halsey]] contacted {{UNSCShip|Infinity}} with information about the attacks. In response, Fireteam Osiris was tasked with rescuing Dr. Halsey from the custody of [[Jul 'Mdama's Covenant faction|Covenant]] [[Supreme Commander|Supreme Commander]] [[Jul 'Mdama]] on the [[Forerunner]] world of [[Kamchatka]].{{Ref/Reuse|osiris}}

After being briefed by Captain [[Thomas Lasky]] of UNSC ''Infinity'', the Spartans were delivered to Kamchatka via [[D79-TC Pelican]], where they discovered the Covenant [[Battle of Kamchatka|engaging]] their former [[Promethean]] allies. Osiris exited the Pelican [[dropship]] to free fall past battling Covenant and Promethean ships, using their armor's thrusters to control their following landing. Osiris landed on a mountainside, where the Covenant and Prometheans were currently engaged in combat and the Spartans fought their way through the terrain. While Vale eliminated Covenant forces aboard a {{Pattern|Mikpramu|Phantom}}, Locke and the rest of Osiris battled numerous Covenant and Promethean forces on the ground. As one of the [[Sangheili blockade runner|Covenant blockade runners]] crashed into a nearby mountain peak, Osiris regrouped and was forced to outrun the ensuring avalanche. The Spartans leaped off a cliff and slide down the mountainside, where they promptly engaged nearby Covenant forces in a valley. With 'Mdama and Halsey located in a nearby Forerunner structure, Fireteam Osiris fought their way past Covenant and Promethean forces to reach their targets' location. Although 'Mdama had a {{Pattern|Shuul'se|Kraken}} deployed to fend off the hostile forces assaulting his location, the Prometheans managed to force the walker to retreat.

After Fireteam Osiris returned to ''Infinity'', Lasky ordered for the fireteam—along with Commander [[Sarah Palmer]] and Halsey—to travel to the Sangheili homeworld of [[Sanghelios]] to utilize the planet's inactive Guardian to pursue Blue Team. Vale and the rest of Osiris were taken to the planet's surface via {{Pattern|Kmiro'sish|Lich}}, where they were tasked with finding Arbiter Thel 'Vadam while he was leading the Swords of Sanghelios against the [[Sanghelios global war|invading]] remnants of 'Mdama's Covenant at the [[Elder Council Chamber]] in [[Nuusra]]. As Osiris engaged Covenant forces, Palmer had [[Mahkee 'Chava]] deploy two [[HRUNTING/YGGDRASIL Mark IX Mantis|Mantises]] for the Spartans to utilize in clearing out the Covenant warriors at the Elder Council Chamber. Upon arriving at the chamber, Osiris battled the Covenant forces assaulting the building and fought their way inside, where they meet up with 'Vadam. With Osiris' help, the Swords of Sanghelios eliminated the Covenant forces at the Council Chamber. Moments later, 'Chava arrived in a Phantom and extracted the Arbiter and Spartans.<ref name="sos">'''[[Halo 5: Guardians]]''', campaign level ''[[Swords of Sanghelios (level)|Swords of Sanghelios]]''</ref> Traveling to the Swords of Sanghelios' encampment at Nuusra, Osiris worked together with Halsey, Palmer, and 'Vadam to formulate a plan to utilize the Guardian. 'Vadam, recognizing Locke as the ONI agent that had planned to assassinate him in the Covenant War, was initially reluctant to move his forces to assist the Spartans. However, when Cortana briefly shorted out all electronics at the encampment, 'Vadam agreed to work with Locke. Osiris was tasked with locating a Forerunner [[Constructor]] at one of the Guardian's nearby support stations to allow Halsey to input commands into the construct to force it to activate the Guardian.<ref name="alliance">'''Halo 5: Guardians''', campaign level ''[[Alliance]]''</ref> Palmer flew Fireteam Osiris to the support station, but was forced to drop them off just south of the facility due to the presence of a Covenant Kraken nearby. While the Spartans provided ground support, the Swords of Sanghelios assaulted the walker from the air. While the Arbiter's flight squadrons forced the Kraken into retreat, Osiris fought their way to an ancient Sangheili temple located near the support facility. After defeating several Prometheans at the temple, the Kraken arrived at the temple, threatening Osiris' mission. As the walker neared, the Spartans boarded the Kraken and destroyed its power generator from within. Osiris fled that doomed walker and traveled into the support facility via stolen {{Pattern|D'nomlhe|Banshee}}s. Once inside the station, Osiris retrieved a Constructor, but were attacked by Promethean forces. After battling their way back to an extraction point with the Constructor, a Phantom transported them back to the Swords of Sanghelios' encampment.<ref name="enemy lines">'''Halo 5: Guardians''', campaign level ''[[Enemy Lines]]''</ref>

With the Constructor, Halsey inputted her commands into it and the construct took off to activate the Guardian. However, the Guardian was located in the [[Csurdon Sea]] next to the city of [[Sunaion]], the last bastion of the Covenant on Sanghelios. The Arbiter's forces regrouped and prepared to attack the city to eliminate the Covenant and give Osiris a chance to board the Guardian.<ref name="before the storm">'''Halo 5: Guardians''', campaign level ''[[Before the Storm]]''</ref> Traveling to Sunaion with a squadron of air vehicles, Fireteam Osiris, Arbiter 'Vadam, and several Swords of Sanghelios forces were deployed to Sunaion and [[Battle of Sunaion|engaged]] Covenant soldiers throughout. While the Arbiter led his forces against the Covenant directly, Osiris destroyed Covenant [[Upisa'weri-pattern Shrike|anti-air emplacements]] to allow the Arbiter's [[fleet]] to move in closer to the city. Unable to receive air support for transport to the Guardian, Osiris accessed Sunaion's undercity to travel to its location. When the Constructor activated the Guardian, Promethean forces arrived at the battle and began engaging the Spartans, as well as the Arbiter and his forces. When the Guardian began rising out of the sea nearby and started to activate its shockwaves, the buildings around the Spartans were ripped apart. As the Spartans moved to safety, they regrouped with the Arbiter as he was engaging Promethean forces. The five battled the onslaught of Prometheans, which were soon led by the Warden Eternal, now utilizing another physical body. After a lengthy engagement, the five destroyed the Warden and the nearby Prometheans just as the Guardian prepared to leave. While the Arbiter remained behind to finish eliminating Covenant and Promethean forces, Palmer and Halsey picked up Osiris in the Pelican and flew towards the Guardian. A pursuing Banshee damaged the dropship, though Palmer was still able to drop Osiris off on the Guardian's surface just as it entered slipspace and left Sanghelios.<ref name="sunaion">'''Halo 5: Guardians''', campaign level [[Battle of Sunaion (level)|Battle of Sunaion]]</ref>