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February
February 2
 * The Shadow of Intent leaves the Urs system for a diplomatic mission in former Covenant territory.

February 21
 * The is commissioned into service.

May-June
May 6-June 1
 * The Shadow of Intent participates in naval exercises with the UNSC Navy in a Joint Occupation Zone. After this, the Shadow of Intent is tasked with the protection of Sanghelios and Sangheili colonies.

June
June 19 June 27 June 30
 * The arrives at the ruins of Installation 00 and deploys several remote contact teams to Installation 00's surface.
 * After 8.3 days, all contact with the RCTs is severed. Only RCT-06 returns to the Rubicon, 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.
 * 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 Librarian could be found.

July
July 2
 * 48 hours after Rubicon's last notice, the ONI sends search and rescue teams to find the ship, but the Rubicon is not found.

July 2-July 21
 * Codename: SURGEON sends to Codename: COALMINER a five-reports series about the status quo of the post-war galaxy.

July 21
 * Having tried in vain for three years, Jul 'Mdama's Covenant faction finally gain access to the shield world Requiem; Shipmaster Jul 'Mdama orders his forces to board to keep the ship from landing on Requiem. Aboard the Forward Unto Dawn, Cortana wakes John-117 from his cryotube and warns him of the intruders. Once off the frigate, they are forcibly pulled into Requiem.

July 21-July 24
 * John-117 and Cortana engage Covenant forces on Requiem while attempting to find a way back to UNSC-controlled space. Meanwhile, is approaching Requiem, oblivious of the gravity well which pulled the Dawn and many Covenant ships inside. While attempting to clear the communications interference preventing them from contacting Infinity, John-117 and Cortana are attacked by mechanical Promethean forces. Activating a supposed broadcast relay in Requiem's core, John-117 instead accidentally releases the Didact from imprisonment. Bent on preventing human ascendance, the Didact leaves immediately and joins forces with the Covenant.


 * UNSC Infinity crashes on Requiem. The Didact makes for the crash-site, followed by the Master Chief, who reunites with the UNSC for the first time in years and assists in the defense of the stranded Infinity, eventually driving back the Didact and the Covenant forces. Afterwards, Captain Andrew Del Rio has a difference of opinion with the Master Chief on whether or not they should leave Requiem, or stay and deal with the Didact. In the end, Del Rio orders the Chief to join Gypsy Company and destroy Requiem's gravity well generator so that the Infinity can depart.


 * During the mission, John-117 encounters a vision of the Librarian, who warns him of the Didact's plan: to use a machine known as the Composer to neutralize humanity once and for all. To fight the Didact, the Librarian provides the Spartan with additional genetic enhancements, including an immunity to the Composer. Once the gravity well is destroyed, Captain Del Rio orders the Infinity to leave Requiem immediately. Disobeying orders, the Master Chief stays behind in an effort to stop the Didact.


 * Raid on Ivanoff Station: John-117 pursues the Didact as he travels to Ivanoff Station to acquire the Composer. The Didact is eventually successful and uses the Composer to digitize the occupants of Ivanoff, save for John-117 who is saved by the Librarian's enhancements.


 * After the Infinity returns to Earth, FLEETCOM immediately relieves Captain Del Rio of his duties as captain of the ship due to his actions on Requiem; Thomas Lasky is promoted in his place.


 * Between July 22 and July 24, the Didact repeatedly contacts Catalog and requests authorization to take control of the ecumene; Catalog rejects his requests.

July 25
 * New Phoenix Incident: As the Didact plans to attack Earth and wipe out humanity using the Composer, John-117 follows him in close pursuit. When the Didact reaches Earth, the Infinity and the UNSC Home Fleet engage his ship immediately. Armed with a nuclear device, John-117 makes his way into the ship and confronts the Didact, but not before the Forerunner uses the Composer to digitize the population of New Phoenix, URNA. With the aid of a rampant Cortana, the Master Chief is eventually able to defeat the Didact and destroy his ship. Cortana sacrifices herself to save John-117 from the explosion and the Spartan is recovered from the debris field soon after.

July 25-July 28
 * During a period of three days, after his return aboard Infinity, John is debriefed. Following his debriefing, John leaves Infinity.


 * After the New Phoenix Incident, Gabriel Thorne volunteers to be a member of the SPARTAN-IV program.

December
December 5
 * Roland becomes the 's AI.