UNSC Pillar of Autumn

"There was only one ship."

- Thel 'Vadamee

"One? Are you sure?"

- Prophet of Regret

"Yes. They called it the Pillar of Autumn."

- Thel 'Vadamee

The UNSC Pillar of Autumn, (Hull Classification Symbol C-709), was a  in the UNSC Navy. It was informally referred to as the Autumn, and its name abbreviated to "PoA".

Prior to the Fall of Reach the Pillar of Autumn was selected to support a SPARTAN-II operation to capture Covenant leaders. Captain Jacob Keyes was placed in command. The operation was forestalled by the Covenant assault on Reach; the cruiser was one of the few UNSC survivors and fled the system having lost most of its intended SPARTAN-II passengers.

The cruiser was guided to the Soell system by the AI Cortana. There it was engaged by a Covenant fleet guarding Installation 04. Keyes crash-landed the ship on the installation where the surviving crew continued the battle against the Covenant and, later, the Flood. The ship's sole remaining combat effective SPARTAN-II, John-117, was forced to detonate the Pillar of Autumn's fusion reactor, destroying the ship and the installation, to prevent the installation from firing.

Human-Covenant War
The Pillar of Autumn was constructed at the Reyes-McLees Shipyards on Mars in 2509.

It saw action during the First Battle of Arcadia against the Covenant in February 2531. The cruiser was heavily damaged engaging two s. The cruiser contributed experimental M-145D Rhino to the ground fighting.

The cruiser was decommissioned with the remaining s, but was reactivated as the war worsened. The Pillar of Autumn was refitted in 2550 to serve in Zeta Doradus.

A chariot for Spartans
By 2552, it was obvious to the UNSC that the war could not be ended with conventional military action. A desperate plan was conceived to end the war by capturing Covenant leaders and forcing the enemy to the negotiating table. SPARTAN-II commandos would commandeer a disabled Covenant ship, locate the Covenant homeworld, and abduct the targets. The Pillar of Autumn was selected on August 25 by the AI Cortana to disable an enemy ship and deliver the Spartans aboard; the ship was selected for the Halcyon-class's durability, despite its class's usual lack-luster offensive capabilities. Command of the ship was given to Captain Jacob Keyes.

The cruiser received another refit for the new mission, including a state-of-the-art fusion power plant. Cortana was transferred to handle the shakedown.

Fall of Reach
The Pillar of Autumn was prepared to deploy on August 30. However, before it could depart the Epsilon Eridani System it was recalled to Reach; the UNSC fleet was mustering in preparation for an imminent Covenant attack on the planet. Cortana remained in control as the ship's normally assigned AI was not yet operational.

It was hoped an opportunity to capture an enemy ship would present itself, however the course of the battle forced the Spartans to deploy on other missions. Blue Team went to Reach Station Gamma to enforce the Cole Protocol, while Red Team went planetside to reinforce the Orbital Defense Generators. While the cruiser performed well, the battle was lost as the Orbital Defense Platforms fell silent. There was only time to recover the remnants of Blue Team, John-117 and the clinically dead Linda-058, before the ship was forced to flee the system.

During the space battle over Reach, Pillar of Autumn defeated a Covenant supercruiser that even few UNSC carriers could not defeat, all by itself, proving Pillar of Autumn is one of the most durable warships ever built by UNSC Navy.

At some point during the conflict, the Pillar of Autumn returned to drydock at the Aszod ship-breaking facility. Shortly before the ship fled the system, the remnants of Noble Team were tasked with delivering a fragment of Cortana's data chip to the Autumn. The ship left drydock immediately afterward.

The Pillar of Autumn was supposed to have made a random Slipspace jump in accordance with the Cole Protocol. However, Cortana surreptitiously guided the ship to the Soell system and, ultimately, to Installation 04 instead. The AI used coordinates obtained from a Forerunner artifact on Sigma Octanus IV. The Covenant pursued along the cruiser's exit vector and arrived at Soell first with a battle group of s.

The Battle of Installation 04
The Pillar of Autumn was immediately engaged upon arriving at Threshold. The cruiser was spared destruction by the Covenant's commanding Minor Prophet, who feared stray plasma torpedo fire might damage Installation 04; the Covenant made to board and capture the ship instead. The Pillar of Autumn destroyed four ships and damaged the Truth and Reconciliation before boarders disabled its Magnetic Accelerator Cannon with an Antimatter Charge.

Captain Keyes ordered the crew to abandon ship. John-117 was given Cortana for safekeeping, and ordered to keep the AI out of enemy hands. The crew left the ship for the ring in whatever craft were available and the cryo pods were jettisoned. Keyes directed the Pillar of Autumn on a course to crash land on the ring. The Covenant finally began hitting the ship with plasma torpedoes, but the cruiser survived the landing reasonably intact. The survivors transferred supplies from the ship to Alpha Base.

The release of the Flood added an unexpected dimension to the battle. Monitor 343 Guilty Spark was preparing to fire the installation in response to the outbreak; in conjunction with the entire Halo Array this would wipe out all sentient life in the galaxy. John-117 and Cortana returned to the Pillar of Autumn to destroy the ring by detonating the still-functioning fusion reactors. An attempt to activate the cruiser's self-destruct from the bridge failed due to 343 Guilty Spark's interference. The Spartan was forced to manually destabilize the reactors with tactical ordnance. The Spartan and AI escaped the subsequent detonation and the ring aboard a Longsword fighter still docked in Launch Bay 7.

Specifications
The Pillar of Autumn was roughly 43 years old at the time of its escape from Reach and later destruction on Installation 04. It was a cruiser of the Halcyon-class, the smallest cruisers in the UNSC Fleet. Like other Halcyon ships, the Autumn was equipped with a honeycombed internal bracing structure that allowed it to function even after sustaining critical levels of damage.

Power plant
The Pillar of Autumn was refitted with an improved nuclear fusion engine that featured two smaller reactors around a larger one, which were capable of boosting the overall power output by 300% for a short time if needed.

Fusion reactors generate extreme heat which must be removed in order for them to remain active without overheating. The Autumn's overhauled reactors were an especially severe case of this. Usually, the excess heat was conducted to a chemical agent which would then vent into space. However, the Autumn's upgraded specifications also included an upgraded cooling system, which featured a "laser-induced optical slurry of ions chilled to near-absolute zero", which is far more efficient than the typical method and removed the reliance on expendable chemical temperature-control substances. In essence, the amount of excess heat removed by the new system increased as the reactors' output did. This self-regulating and self-cooling power plant was critical in combat since it virtually eliminated a commander's concerns about overheating and slagging a ship's engines.

The Pillar of Autumn's reactor was able to be overloaded by explosives, either grenades or rockets, destroying the vulnerable vent cores. Once these were destroyed, the reactor began to go critical, resulting in temperatures of over 100,000,000 degrees and a thermonuclear explosion large enough to tear apart a Halo Installation.

Armament
The upgraded Pillar of Autumn received extensive refits, including several to its weapons systems. Eventually, it was host to a very powerful armament; far in excess of the original Halcyon-class ships.
 * With extra power capacitors and power recycling systems, the Pillar of Autumn's MAC gun could fire three consecutive shots per charge.
 * The MAC gun fired lighter projectiles compared to most ship grade MACs, but these rounds worked much like Shredder Rounds. Each charge was able to fire 3 rounds.
 * 300 Archer Missile Pods which were arranged in thirty columns and ten rows. Each pod contained 26 individual devices, equaling 7800 missiles
 * Four Shiva-class Nuclear Missile, one loaded onto a remote-controlled Longsword interceptor, and three ship-launched.
 * Forty 50mm MLA Auto-cannons with overlapping fields of fire for point defense against single ships. These cannons were later salvaged by the surviving humans on Installation 04 for Alpha Base.

Engine room
The Pillar of Autumn 's engine room 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 Installation 04. This room is the largest room in the Pillar of Autumn with the exception of the hangar bay and the "Leap of Faith" room.

Airlocks

 * Airlock 31, 32: Lifeboats destroyed by the Covenant to make way for a Boarding Craft.
 * Airlock 51: Lifeboat was destroyed by unseen Covenant artillery as it departed from the airlock.
 * Airlock 52, 53, 61, 62, 63: Lifeboats managed to make it out of the vessel.1

1 Airlock 61: the Master Chief, Cortana, nine other Marines on board and the Bumblebee pilot.

Trivia

 * The Pillar of Autumn s model is approximately 1.17 km long, a reference to John-117. The ship's length is exaggerated in final level of Halo: Combat Evolved to provide a 3 km long vehicular course.
 * The Marathon logo is prominently displayed on the Pillar of Autumn 's starboard and port sides in Halo: Combat Evolved The ship's official emblem has the Marathon logo as well. The marathon logo was also visible in the window of the ship in the opening cut scene of the level The Maw. However, the ship's official emblem is the Seventh Column logo in Halo: Reach, as seen on the hull of the Pillar of Autumn and Captain Keyes' ID Patch.
 * The bulletin board just outside the bridge of the ship contains a number of amusing clips, some throwbacks to Marathon. These can be examined on the first level of Halo: Combat Evolved. The board has a flier for a missing cat called Jonesy. This is a reference to the Alien movies, where the cat's name was Jonesy. The board also has a flier telling Marines to 'Keep it Clean', a quote later used in Halo 3: ODST.
 * Prior to being refit for the Spartan mission, the Pillar of Autumn was equipped with Mark II fusion engines (which supplied only 10% the power of modern reactors), and had just one regular MAC gun and six Archer missile pods.
 * In Halo: The Fall of Reach, the Autumn is described as having a command chair. In Halo: Combat Evolved, this chair is absent. Also in Halo: The Fall of Reach, the Autumn seems to have a rotating section in it to simulate gravity. However, in Halo Combat Evolved, the ship has gravity in areas that could not be in a rotating drum. The bridge is an example. As Halo: Contact Harvest pointed out that Human-engineered artificial gravity was in existence in 2525, it is possible that the Autumn was being converted to use artificial gravity. The player may simply not visit areas still using rotating sections.

List of appearances

 * Halo: Combat Evolved
 * Halo 2
 * Halo 3
 * Halo Wars
 * Halo: Reach
 * Halo: The Fall of Reach
 * Halo: The Flood
 * Halo: First Strike
 * Halo Wars: Genesis
 * Halo Legends
 * Origins
 * Odd One Out