2554

January

January 3

• Insurrectionist forces of the United Rebel Front unsuccessfully attempt to invade and occupy Draco III's rebuilt capital of New Albany, resulting in a prolonged standoff between themselves and the UEG. Standoff results in the death of all insurgents but at least one UNSC soldier who was being held hostage was killed.

March

March 29

• An incident occurs on a space station operated by the SPARTAN-IV program as a training facility, beginning with the murder of Spartan-IV trainee Hideo Wakahisa by fellow Spartan candidate Rudolf Schein, now working as an agent of the United Rebel Front. Schein subsequently attempts to destroy the station with explosives, though Musa-096 and Jun-A266 are able to stop him; however, Captain O'Day is killed in the process, while Jun and Schein are propelled into space through a breached viewport. Jun is rescued on time by Lucy-B091 and Tom-B292 while Schein is left to die in the vacuum of space, with the three Spartan-IIIs receiving medical treatment for several days for their vacuum exposure.

April

Unknown date

• Shortly after Schein's failed terrorist attack, Tom-B292 and Lucy-B091 are reassigned from their duties as Spartan-IV instructors to serve under Franklin Mendez as part of the security staff of the Onyx United Research Project on Shield World 006.

April 22

• Shadow of Intent is rendered combat ineffective after a battle with Jul 'Mdama's forces.

August

August 10

• UNSC Rubicon arrives at the ruins of Installation 00 and deploys several remote contact teams (RCTs) to the Ark's surface.

August 18

• After 8.3 days, all contact with the RCTs is severed, after being attacked by the installation's fauna and constructs. Only RCT-06 returns to the prowler, having suffered extensive casualties. However, they bring the source of the signal aboard: the remains of the monitor 343 Guilty Spark.
• After properly calibrating their AI translator, the human team began to interrogate Spark, hoping to gain insight into the ancient human-Forerunner relations and the Didact. Spark, acknowledging the humans as "the true Reclaimers" proceeds to describe the events that led to his former human self becoming a monitor.

August 21

• After Spark finishes his story, his robotic shell powers down and is jettisoned into space by order of the ONI team commander. Having successfully uploaded his data stream into the ship's computers, however, Spark disables Rubicon's AI and takes full control of the vessel. Having come to the conclusion that the Librarian is alive as a result of long study, and that he has need for the ship and its crew, Spark puts them to sleep and sets course to where he believes the Lifeshaper could be found.
• Bobby Kodiak, the only survivor of the RCT Broadside, is "saved" and converted into a cyborg by 000 Tragic Solitude after surrendering himself to the AI.

November

November 21

• Indrid Lota dies on Aleria.

December

December 15

• Dr. Catherine Halsey, working on Ivanoff Station, files an audio log regarding the discovery of the Composer on the nearby Installation 03 and is fascinated by the similarities between the Forerunner device and the UNSC's AI matrix compiler.

Unknown date

• Jul 'Mdama and his followers find the shield world Requiem. They attempt to gain entrance to the shield world but are unsuccessful until 2557.

• The United Nations Space Command's Budgetary Retention Hearings of 2554 are held.

• Tedra Grant visits Earth for the first time.

• The Battle of Draetheus V takes place as Covenant forces under Merg Vol attack Draetheus V. The battle sees significant losses on both sides and Draetheus V itself is nearly destroyed when Merg Vol's activates X50. The main hostilities conclude with Spartan Sarah Palmer killing Vol and sabotaging X50's main weapon, bringing the Covenant's quest to a halt.

• Some time after the battle, the Covenant return when a looping Forerunner code begins emanating from X50. After arriving at the source of the signal, Spartan Palmer discovers that the source is the remains of Spartan Edward Davis.

• The Alerian mining union Mols'Desias is dissolved. Silas Lota dies shortly after.

• Jordan Gaines is transferred from the UNSC Air Force to ONI Section One.

• The Concord incident takes place, involving the use of outer-plated Mjolnir armor legs by Spartan-IVs.

• A recolonization support fleet of the UEG arrives to Alluvion, discovering a strange anomaly under the planet's Sundark Sea; Forerunner shield pylons, which emerged and forced back massive walls of water revealing the seafloor.

• Fathom Station is commissioned by Imbrium Machine Complex and designed to locate the crash sites of Splendid Intention and UNSC Of Uncommon Courage.

• Naphtali Contractor Corporation took control over the EOD-class Mjolnir production.