Requiem

Requiem was a Forerunner shield world located in the Milky Way galaxy. It once served as the central base of operations for the Prometheans, an elite class of Warrior-Servants, for thousands of years until the end of the Forerunner-Flood war. It remained sealed off for a hundred millennia since the end of the war, and became the site of major events as UNSC and Covenant forces stumbled upon it in 2557. By early 2558, the forces of the, stationed at Requiem, continued to face opposition from both the occupying Prometheans as well as the Covenant, until the installation's destruction.

Forerunner era
Requiem was constructed sometime prior to the Human-Forerunner War and once belonged to the Warrior-Servants, the Forerunners' designated military class. When the other Shield Worlds were being constructed Requiem served as a template for them. It served as the home of the Warrior-Servants' Promethean class, and was a central hub for all Forerunner forces and war efforts. It was sealed during the Forerunner-Flood war by the Librarian, who imprisoned the Ur-Didact in the core of the shield world to prevent him from using the Composer on all of humanity and turn them into war machines in his army. Before leaving Requiem, the Librarian left on the planet a personality impression of herself, along with the Janus Key.

Rediscovery


In 2554, Jul 'Mdama and his Covenant remnant faction discovered Requiem, using coordinates provided by Forerunner symbols. Over the next three years, the Covenant tried to enter the planet, without success.

In summer 2557, the severed aft section of the UNSC frigate Forward Unto Dawn, containing John-117 and Cortana, drifted near Requiem and were forcibly pulled inside an automated entrance portal on its surface, along with a number of ships from a Covenant fleet and later, the prototype starship. Inside, they encountered hostile Promethean forces that occupied the structure, and unwittingly released the Didact. The humans battled their way through the world, destroying its gravity well generator so the Infinity could escape. The Infinity escaped from the shield world, and despite the best efforts of the Master Chief and Cortana, the Didact escaped as well to go after the device known as the Composer, chased by the two in a Lich. Six months later, the Infinity returned to Requiem in order to establish research facilities to study the installation, facing both the local Prometheans and Covenant remnant forces which still occupied the structure.

Destruction
In February 2558 Jul 'Mdama, believing to have obtained the artifact they sought, put Requiem on a collision course with the sun, with the Infinity anchored to the planet. Fireteams Majestic and Crimson were sent to deactivate two artifacts that kept the ship anchored, while Henry Glassman deactivated the third one aboard the Infinity. After many complications, both fireteams reached their objective and the Infinity was able to flee the planet, seconds before Requiem was consumed by the sun, which went supernova immediately afterward.

Structure
The most resilient shield installation built by the Forerunners, Requiem consisted of multiple concentric planetary shells enclosed within one another, sealed inside an enormous outer shell. The outermost surface was an armored covering enveloping the second shell, which was oriented like that of a planet and housed the world's primary terrestrial environment. Requiem's core was located below this planetary surface, and had a surface reverse to that of the terrestrial exterior, similar to a miniaturized Dyson shell.

Requiem's outer surface was a thick metallic shell lacking a terraformed surface and covered in patterns and layers of machinery and overlapping armor plating. The surface was also covered in a number of lights; some of these formations took on geometric patterns, such as circular orientations or arrays of lines. Amongst its complement of luminous formations were two enormous symbols; the Eld, (which represents the Mantle), as well as the Reclaimer glyph. Though the full extent of the technology of the mechanical exterior shell has not been documented, it is known that as a type of shield world, it was capable of protecting its interior from the effects of the activation of the Halo Array.

The interior of the facility was unique relative to the other known shield worlds; rather than housing an artificial star at its center, surrounded by a habitable inner surface, the exterior shell housed additional layered shells, the outermost of which had an environment resembling a terrestrial planet. Another important feature was that immediately above the cloud layer of the protected second layer, the interior surface of the protective shell was visible. This was demonstrated by the sky being dominated by the machinery above it, with large, vertical structures reaching down to the surface below. Requiem's artificial star was located in the machinery above the interior planetary shell. It is unknown how day and night cycles were implemented, specifically relative to the significant number of structures anchored to the planet's surface.

The innermost miniature Dyson shell housed the core of Requiem, which was where the Didact's Cryptum was situated. The platform which housed the Cryptum was suspended in the very center of the sphere and was protected by a shield emitted by two adjacent pylons located on opposing sides on the surface of the inner sphere. Two enormous energy conduits perpendicular to one another ran between the pylons across the entire inner surface. The surface in the inner shell mostly consisted of rocky desert landscape dense with prominent arrangements of light indicating the presence of large-scale structures.

Features
A readily seen feature of this construct is that it harbored a number of large circular entrance portals, with iris-type opening mechanisms. When opened, a vibrant, blue-white light could be seen emanating from the interior. These portals featured the ability to generate artificial gravity wells, drawing in objects in the immediate vicinity if the presence of Reclaimer is detected. These gravity wells were powered by generator complexes situated somewhere on the inner planetary shell.

The next known aspect of this facility is that it possessed fully active and functioning technology, unlike other Forerunner sites, which have largely been abandoned and dormant, with the exception of Shield World 006. Examples of such active technology included enormous spires suspended in the air without visible support and structures capable of shifting and reconfiguring themselves, extensive use of sophisticated hard light construction to create structural elements, or the Prometheans' various weapon and equipment caches found across the shield world.

For travel between the layers and various locations, Requiem used teleportation portals that could transport anyone who used them to different locations on the shield world. Due to her experience and expertise with Forerunner technology, the AI Cortana was capable of controlling these portals. The Prometheans that occupied Requiem were capable of generating portals and translocating across the shield world.

Locations

 * Apex
 * Control
 * Copernicus Base
 * Cyclone
 * Fortress
 * Galileo Base
 * Great Anvils
 * Lockup
 * Quarry
 * Ravine
 * Sniper Alley
 * The Cauldron
 * The Gate
 * The Refuge
 * Two Giants
 * Warrens

Trivia

 * A requiem is a church mass celebrated for the repose of the soul(s) of one or more deceased persons. This may be a reference to the Forerunners' mass extermination following the firing of the Halo Array, or to the fact that John-117 has been presumed dead by the UNSC.
 * Prior to Halo 4, Requiem was known among fans as the Legendary Planet. This is a reference to the planet's first appearance in an exclusive ending in Halo 3, which is viewable only by completing the last level of the game on Legendary difficulty. In the ending, the aft section of the Forward Unto Dawn is seen drifting toward the planet; seconds later, a light shines across the surface of the planet, as the Forward Unto Dawn is caught by the planet's gravity. Requiem also appears in a small image in the Halo Encyclopedia, where it is shown to have a reddish-orange color on a small illuminated section. The planet appears again in the Halo 4 announcement trailer, where the aft half of the Forward Unto Dawn is seen being pulled into a massive, iris-like opening on its surface. The planet was finally identified as "Requiem" in the May 2012 issue of the GameInformer magazine.
 * An image of the planet is present in the bulletin board of the in Halo: Combat Evolved Anniversary, in a poster for a fictional film titled Dark Planetoid Rising.
 * On the surface of the planet, as seen in the Legendary ending for Halo 3, a third symbol can be seen alongside the Reclaimer and unspecified Forerunner symbol; The 7-spoke insignia of the Bungie fan community known as Seventh Column. The symbol for Reclaimer is also the insignia for Marathon, a game trilogy made in the years before Halo: Combat Evolved was developed.
 * According to Brian Reed, the lead writer of Halo 4, Requiem is the largest Forerunner construct in history. He was ostensibly speaking hyperbolically, as simple observation of Requiem's size as seen in the game's cinematics (specifically, based on the curvature of the horizon on the outer shell, the size of the entrance portals relative to the shell or several objects observed near it, or the size of Requiem relative to its sun before its destruction) indicates that the structure would be closer to the scale of an Earth-like planet, if not smaller. If Reed meant that Requiem is merely the largest construct featured in the games, it would be larger than the 100,000 kilometer lesser Ark, although even this would seem unlikely given the aforementioned observations.
 * Early concept art for Halo 4 display a decidedly different concept for Requiem's entry portal than the final game. Whereas in the game, the entrance opens directly to the inner planetary shell underneath, several works of concept art depict the interior of the opening as a cavernous, structured space which appears to lack gravity.
 * Requiem is designated as "43121124" by the holographic terminal displaying the Dawn's predicted drift course.
 * Requiem being pulled into its sun was originally suggested as a joke by Frank O'Connor.

List of appearances

 * Halo 3
 * The Commissioning
 * Halo: The Thursday War
 * Halo 4: Forward Unto Dawn
 * Scanned
 * Halo 4
 * Halo: Silentium