2559

2559 was a year in the 2550s in the 26th century. It was a time period filled with many large battles: the ongoing violent Sangheili-Jiralhanae war, an isolated skirmish on Installation 00 between the UNSC Spirit of Fire and the Banished, and the overarching Created conflict.

January
January 16 January 17 January 23 January 24
 * The survivors that fled the Henry Lamb Research Center on Installation 00 stumble upon a transport route set up by the Banished to move mined resources. The group rests and argues for a while concerning which direction they should head in next.
 * Nathaniel Palmer records that including himself, only eight survivors in their group remain.
 * Aboard the, Spartan 92738-61842-LC of Fireteam Apollo interviews Spartan Commander Sarah Palmer as part of their investigation concerning the root cause of the recent decisions made by the artificial intelligence Cortana.
 * Spartan 92738-61842-LC continues their investigation regarding Cortana with an interview of Doctor Catherine Halsey, her creator.

February
February 10
 * The MJOLNIR Powered Assault Armor (GEN3) enters into service.

March
March 4 March 28 March 29 On or before March 30 March 30
 * Orda Val 'Saham records his thoughts on one of the Ark's Cartographers and its link to the Covenant faith.
 * After 28 years of drifting in space the finds its way to the orbit of the Forerunner Installation 00, known as the Ark. Awakened from cryo-sleep, the crew eventually travels down to the Ark to find out how to establish contact with the galaxy. However, on the surface of the Ark they encounter a hostile, violent mercenary faction known as the Banished, led by the cunning Jiralhanae warlord Atriox.
 * Seth, an A.I. aboard the Spirit of Fire, cross-analyzes transcripts, incident report data, and a past surveillance report provided by the Logistics Smart A.I. Isabel in order to compile a research report on Atriox for Captain James Cutter. Ellen Anders learns more about the Forerunners thanks to Isabel, and wonders about the Librarian's plan for humanity, but she focuses her attention on helping the crew against the Banished.
 * The Spirit of Fire forces make an assault on the Ark's Cartographer, and learn about the Banished use of the Ark's translocation portal network.
 * Two Unggoy attempt to desert the Banished, but they are executed by Balkarus.
 * Orda Val'Saham records his thoughts on the UNSC's capture of the Cartographer in his personal journal.

April
On or before April 2 April 2
 * Decimus is killed by UNSC forces. Immediately after his death, the Spirit of Fire is attacked by the Enduring Conviction.
 * Enduring Conviction is destroyed by Jerome-092 and Isabel when they forced the Ark's Aggressor Sentinels into attacking the ship. A Halo ring is discovered on the Ark's Foundry.
 * Ellen Anders and Installation 09 leave Installation 00 in hopes of getting to the Soell system, but are intercepted by a Guardian before they arrive.
 * James Cutter records his thoughts on the departure of Installation 09 in his personal journal.

May
May
 * Operation: SPEARBREAKER - Sunray 1-1 manage to halt the Banished plan of using a Forerunner to destroy the Spirit of Fire.

June
June 1 June 4
 * Comms officer G. Peterson records what he observes of the area surrounding the wreckage of High Charity on Installation 00.
 * Lieutenant Voridus of the Banished inadvertently releases the Flood from within the containment shield around High Charity. Voridus and his brother Pavium manage to reactivate the Sentinels, kill the Proto-Gravemind, and drive the Flood back into containment within the former Covenant city.

September
September 19
 * Doctor Catherine Halsey modifies John-117's third-generation Mjolnir armor.

October
October 7 October 12 October 14
 * Blue Team is sent to recover top-secret assets from the ruins of CASTLE base on Reach.
 * The Banished opened the portal from Reach to the Ark, allowing Atriox to return to the galaxy. Castor led his detachment of the Keepers of the One Freedom in hijacking Atriox's lich to reach the Ark. The Covenant, UNSC, and Banished fought a three-way battle for control of the portal.
 * Ferrets, along with the UNSC Spirit of Fire and the Banished's Clan of the Long Shields, destroys Intrepid Eye and Castor's remaining Keepers on Epsilon Clarion to prevent Castor and the Covenant Loyalists from triggering Halo's firing mechanism.

November

 * Cortana uses multiple Guardians to destroy the Jiralhanae homeworld of Doisac in an attempt to force Atriox into submission.

December
December 11 December 12 December 13 December 15 December 18 December 26 December 28
 * Dr. Halsey briefs John-117 on the Weapon's mission to contain Cortana prior to the arrival at Installation 07; Thomas Lasky assigns Blue Team to an unspecified operation and Jameson Locke for Operation: BREAKER TRIP.
 * The arrives at Installation 07, but is suddenly ambushed by at least 4 Banished dreadnoughts and artillery. Atriox defeats John-117 in one of the Infinity's hangars.
 * Cortana destroys a fragment of Installation 07 and herself to deny Atriox and his Banished forces control of the Ring, unintentionally aiding fireteams Taurus and Intrepid on their mission.
 * Spartan Makovich assists the UNSC in building a foothold on the ring within the remnants of UNSC Mortal Reverie.
 * Spartan Griffin briefs the UNSC survivors of the Banished occupation of Installation 07.
 * Spartan Horvath eavesdrop on Banished Jiralhanae arguing over a potential key choke point.
 * Spartan Sorel and a squad of Marines discover that Installation 07 is slowly reparing itself.

Unknown date

 * A Sangheili shipmaster returns to the glassed human colony of Kholo. The species wide war between the Sangheili and the Jiralhanae is still ongoing.
 * Yapyap rebels against the Banished.