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: 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.
 * January 17: Nathaniel Palmer records that including himself, only eight survivors in their group remain.
 * January 23: 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.
 * January 24: 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: Orda Val 'Saham records his thoughts on one of the Ark's Cartographers and its link to the Covenant faith.
 * March 28: 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.
 * March 29: Seth, an A.I. aboard the Spirit of Fire, cross-analyses 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.
 * March 30: Two Unggoy attempt to desert the Banished, but they are executed by Balkarus. Decimus is killed by UNSC forces. Immediately after his death, the Spirit of Fire is attacked by the Enduring Conviction.

April

 * April 1: The 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.
 * April 2: 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.

May

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

June

 * June 1: Comms officer G. Peterson records what he observes of the area surrounding the wreckage of High Charity on Installation 00.
 * June 4: 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 contain the Flood back into the former Covenant city.

September

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

October

 * October 7: Blue Team is sent to recover top-secret assets from the ruins of CASTLE base on Reach.
 * October 12: The Banished opened the portal from Reach to the Ark, allowing Atriox to return to the galaxy. Castor led 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.

December

 * December 11: Dr. Halsey briefs John-117 on the Weapon's mission to contain Cortana prior to the arrival at Installation 07.
 * December 12: The UNSC Infinity arrives at Installation 07, but is suddenly destroyed by Banished dreadnoughts and artillery. Atriox defeats John-117 as the Infinity is destroyed.
 * December 13: 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.
 * December 15: Spartan Makovich assists the UNSC in building a foothold on the ring within the remnants of UNSC Mortal Reverie.
 * December 18: Spartan Griffin briefs the UNSC remnants of the Banished occupation of Installation 07.
 * December 26: Spartan Horvath eavesdrop on Banished Jiralhanae arguing over a potential key choke point.
 * December 28: 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.