UNSC Pillar of Autumn

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The was a heavily modified  of the. It was informally referred to as the Autumn by UNSC personnel.

History
Mothballed and due to be scrapped like the remainder of the Halcyon-class, the Human-Covenant War saw the reactivation of the Pillar of Autumn. The refit she subsequently received rectified a number of deficiencies in the original design and made her a competitive re-addition to the sorely pressed UNSC Navy. At the time of her destruction in 2552 she was 43 years old. The Pillar of Autumn saw action at the Battle of Reach and was one of the two ships to escape the disaster, albeit with moderate damage. Although the Cole Protocol demanded a random Slipstream jump, the AI Cortana, unbeknownst to the crew, purposely guided the ship to the planet Threshold based on map coordinates extracted from a Forerunner artifact. The result was the discovery of Installation 04, or "Halo". A brief and uneven battle against a Covenant battle group of a dozen superior s in near-Threshold space resulted in critical damage being inflicted upon the Pillar of Autumn. Enemy boarding parties disabled the Magnetic Accelerator Cannon's fire control with a demolition charge, but not before she made a good account of herself by destroying four enemy warships and damaging several others. The Pillar of Autumn's survival against superior forces was due in part to a Prophet's directive to disable, rather than destroy, her out of fear that her destruction might harm "Halo", which had religious significance to the Covenant. The ship was then crash landed onto "Halo" by her captain, coming to rest upright and balanced over a cliff on a barren peninsula.

Prior to the crash much of her crew had taken to the escape pods, including the Master Chief whose suit was carrying Cortana in a bid to prevent the AI's capture. Others evacuated by Pelican dropship or even in drop pods, as was the case for a complement of ODSTs. Despite the confusion most of the crew survived to reach "Halo" and engage Covenant ground forces, Pelicans were employed to retrieve munitions from the crashed ship to sustain this effort.

Despite the abuse sustained during the space battle and the following crash the Pillar of Autumn remained intact, and was subsequently occupied by investigating Covenant forces and later by Flood. The threat posed by the latter was deemed sufficiently great for the Master Chief and Cortana to detonate the ship's still-functioning fusion power cores in a bid to destroy "Halo", thus preventing the Flood from escaping.

Having manually triggered a destabilization of the power cores, the Master Chief and Cortana commandeered a Longsword from one of the Pillar of Autumn's docking bays and achieved a safe minimum distance before the ship exploded, causing the ring-world to fragment.

Power Plant
The Pillar of Autumn was refitted with an improved nuclear fusion engine that featured two smaller reactors around a larger one, capable of boosting power out by 310%. An upgraded cooling system was also retrofitted, featuring "a laser-induced optical slurry of ions chilled to near-absolute zero" that removed the reliance on depleteable chemical temperature-control agents. In essence, the new system provided increased waste heat removal as power output increased. This self-regulating and self-cooling system was critical in combat since it virtually eliminated a commander's concerns about overheating and slagging a ship's engines.

Armament
The upgraded Pillar of Autumn recieved several refits, including several to its weapons systems. Eventually, it was host to a very powerful armament.
 * One MAC Cannon which was capable of firing three consecutive shots on one charge.
 * Three-hundred Archer Missile Pods which were arranged in thirty columns and ten rows. Each pod contained 26 individual devices, equalling 7800 missiles.
 * Four Shiva Nuclear Warheads
 * Forty 50mm Autocannons for point defense against single ships. These cannons were later scavenged by the surviving humans on Installation 04 for Alpha Base.

Engine Room
The Pillar of Autumn's engine room, or just "Engineering", was a large, three-deck high chamber allowing access to the fusion engine core. Side passages allowed for movement from the bottom deck all the way up to the catwalks on the third. The manifolds into the cores were suspended above the second deck. Controls on the third retracted these manifolds, exposing a vent that led directly into the core. It was using this method to expose the core via the vents that the Master Chief ultimately destroyed the ship and "Halo". This room is the largest room in the Pillar of Autumn.

Pillar of Autumn Command Crew

 * Captain Jacob Keyes -- Ship Captain
 * Cortana -- Spartan AI
 * Lieutenant Dominique -- Communications Officer
 * Lieutenant Aki Hikowa -- Weapons Officer
 * Lieutenant Hall -- Operations Officer
 * Ensign William Michael Lovell -- Navigation Officer
 * Lieutenant Commander Gail Purdy -- Chief Engineer
 * Crewman Abiad
 * Crewman Wang
 * Crewman Singh

Other Naval Personnel

 * Tech Chief Thom Shepard -- Cryogenics Technician
 * Tech Officer First Class Mary Murphy -- Air Traffic Technician
 * Tech Officer Sam Marcus -- Cryogenics Technician
 * Petty Officer Third Class Pauley -- Radio Technician
 * Petty Officer Third Class Cho -- Radio Technician
 * Flight Officer Captain Carol "Foehammer" Rawley -- Pelican Pilot
 * Lieutenant "Cookie" Peterson -- Pelican Pilot
 * Lieutenant Rick Hale -- Pelican Pilot
 * Flight Officer Mitchell -- Pelican Pilot
 * Warrant Officer Shiela Polaski -- Pelican Pilot
 * Lieutenant Frye -- Pelican Co-Pilot
 * Crew Chief Cullen -- Pelican Communications Officer
 * Lieutenant Haverson

Individuals

 * Major Antonio Silva
 * First Lieutenant Melissa McKay
 * Second Lieutenant Dalu
 * Second Lieutenant Oros
 * Staff Sergeant Marvin Mobuto
 * Master Sergeant Lister
 * Company Sergeant Tink Carter
 * Sergeant Corly
 * Sergeant Johnson
 * Sergeant Parker
 * Sergeant Stacker
 * Gunnery Sergeant Waller
 * Private First Class M. Fitzgerald
 * Private Bisenti
 * Private First Class Hosky
 * Private First Class Wallace A. Jenkins
 * Corporal Locklear
 * Corporal Lovik
 * Corporal Wilkins
 * Lance Corporal "Snaky" Jones
 * Medic "Doc" Valdez
 * Private Kappus
 * Private Chipps Dubbo
 * Private Manuel Mendoza
 * Private O'Brien
 * Private Marie Postly
 * Private Riley
 * Private Satha
 * Al-Thani
 * Dawkins
 * Mary Murphy
 * Suzuki
 * Crazed Marine (Halo 1)
 * Unnamed Corporal
 * 34 Truth and Reconciliation Marines
 * 6 dead Marines scattered across the Silent Cartographer level.

Units

 * 830 Marines-1 ODST Battalion, 1 Marine Battalion
 * Combat Team Alpha
 * Combat Team November
 * Combat Team Sierra
 * Combat Team Victor
 * Fire Team Charlie
 * Fire Team Zulu
 * Fourteenth Platoon
 * Twenty-Second Tactical
 * Silent Cartographer Assault Platoon

Others

 * Spartan-058
 * Spartan-117
 * Wellsley (A.I.)
 * Cortana

Trivia

 * The Pillar of Autumn is approximately 1.17 km long. This, however, contradicts the final level of Halo: Combat Evolved where the player must drive along a 3 km long service corridor that supposedly runs the length of the ship. This was probably for generating the tension and atmosphere necessary for the level.
 * The Marathon logo is prominently displayed on the Pillar of Autumn's starboard and port sides. The ship's official emblem has the Marathon logo as well.
 * The bulletin board just outside the bridge of the ship[[Image:PoAPoster.jpg|left|thumb|200px|The Bulletin Board]] contains a number of amusing clips, some throwbacks to Marathon. These can be examined on the first level of Halo: Combat Evolved.
 * The length is said to be 1.17 km long, which is the ID number of Master Chief, 117.
 * In reference to Halo: The Flood, when Master Chief is to escape after blowing the engines of the Autumn the Grunt Yayap said to his superior that he will need to escape Exit E-117. 117 is another reference to Master Chiefs number John-117.
 * The Pillar of Autumn mess-hall offered a choice between turkey, hamburgers, cheeseburgers, hot dogs, meatloaf, and a dish named Chef's Special. Beverages included cola, water, lemon/lime, lemonade, root beer, coffee, orange, hot tea, hot chocolate, iced tea, and Chef's Suprise.
 * The Pillar of Autumn was capable of reaching sublight speeds of 1,454 meters-per-second.
 * While the Fall of Reach mentioned the Autumn having a command chair, in Halo: Combat Evolved, such a chair is absent.
 * In cutscenes the Pillar of Autumn never moves it is just a piece of BSP geometry. However the camera's moved in a way that it would seem like it moved.