2531

January

 * The Type-33 Light Anti-Armor Weapon is first encountered by UNSC forces.
 * January 3
 * Admiral Preston Cole orders the to help the  around Harvest.
 * The Planetary Operations Manual for the Spirit of Fire was amended on this date.
 * January 30: Professor Ellen Anders is recruited by the Office of Naval Intelligence.

February

 * The final battle of the Harvest campaign is won in space: Admiral Preston Cole's fleet engages the alien warships that have again returned to the Harvest colony. Six years after the planet was attacked, UNSC forces emerge victorious at great cost.
 * February 4: The enters the Epsilon Indi system and arrives back at a glassed and partially frozen Harvest, encountering the Covenant troops of the Fleet of Glorious Interdiction, led by Arbiter Ripa 'Moramee, that are in the process of uncovering a Forerunner Relic on the planet.
 * The Spirit of Fire discovers the damaged, which has been previously attacked by the Covenant and suffered a critical reactor failure. Sergeant Forge and a team of EVA Marines squad rescue the Prophecy' survivors and destroy the ship to prevent its NAV data from falling into Covenant hands.
 * Captain James Cutter of the makes an entry in his log, reflecting on the five years leading up to this point in the war against the Covenant.
 * Serina instructs that production of M41 LAAG weaponry cease on Harvest, Warthogs instead to be upgraded with the M68 Gauss Cannon. Not that it makes much difference as drivers continue to 'splatter' their Covenant enemies, much to the frustration of their maintenance teams.
 * Helena Roman is KIA against the Covenant. Captain Cutter sends a message to her family in regards to her death.
 * Professor Anders joins the Spirit of Fire's crew.
 * Prof. Anders receives some unexpected readings on an EM band and asks a Hornet squadron en route to Rally Point Baker to investigate. They end up sighting a battalion of Sangheili. Sergeant Forge is assigned to Quadrant 4 to investigate.
 * February 6: Anders writes her father a message detailing her mission to Harvest and the result of her discoveries on the planet, and encodes it as a detailed analysis of Homer's Odyssey. ONI censors miss the cipher completely and the message passes unaltered to her father.
 * February 7: Spirit of Fire holds service for the crew of the UNSC Prophecy. The crew roster is read despite objections from ONI personnel.
 * February 9: Spirit of Fire arrives at the planet of Arcadia during battle, where they meet SPARTAN Red Team.
 * February 10: While investigating the Arcadia Forerunner ruins, Anders is captured by the Arbiter Ripa 'Moramee, forcing the Spirit of Fire to pursue her captors into unknown space. Serina projects an arrival at their destination in 312 hours. The ship remains on high alert for the duration, though nonessential crew members are briefly placed in cryo sleep.
 * February 11: During the Slipspace voyage, Sergeant Forge confronts Douglas-042 over his recommendation to destroy the Covenant ship carrying Professor Anders. The altercation results in a broken chair, a seal malfunction on a bulkhead door, and a stern interruption by Serina.
 * February 14: Serina, knowing that the crew may be on a one way trip, manufactures and delivers fake emails from family members to the crew celebrating Valentine's Day. She uses previous correspondence as a basis for the letters.
 * February 23: Battle of the Etran Harborage. Medical officers aboard the Spirit of Fire mistake the Flood for a virus.
 * February 25: Spirit of Fire escapes the Etran Harborage thanks to the sacrifice of John Forge.
 * February 26: The Spirit of Fire crew burn Flood-infected bodies to prevent the virus from spreading in the ship. Chief Medical Officer O'Neil also decides to cancel any study of the Flood.

March

 * March 1: Chief Engineer Andrew Prescott finishes his assessment of damage to Spirit of Fire and repairs continue to the hull. The FTL core reactor cannot be replaced and plans to manufacture a spare from base reactor units are deemed unworkable. The decision is made to run the ship on a skeleton crew and place the rest in suspended animation.
 * March 3: Captain Cutter files a report in his log, wondering what Anders experienced as a prisoner of the Covenant.
 * March 4: Anders analyzes the events in the shield world and concludes that the beings who built it knew humans.
 * March 11: Anders is put into cryosleep by Captain Cutter.
 * March 12: Captain Cutter writes five commendations, fourteen family condolence letters, and a note to his wife.

May

 * May 1: Raid on Camp New Hope. Spartan-II Blue Team infiltrates Camp New Hope, on planet Victoria, in the 111 Tauri System. General Howard Graves of the United Rebel Front is killed and three FENRIS nuclear warheads are recovered.

June

 * June 12: Feeling she cannot provide her daughter the care she deserves, Dr. Catherine Halsey sends Miranda to live with her father, Lieutenant Jacob Keyes.

October

 * October 24: Colonel James Ackerson proposes the SPARTAN-III program to leading members of Office of Naval Intelligence. The project is approved and implemented immediately.

November

 * November 7: Spartans Kurt-051, Kelly-087 and Fred-104 are dispatched to investigate Construction Platform 966A for suspected rebel activity. Kurt-051 experiences a thruster pack malfunction and is sent into interplanetary space. The prowler and the frigate  start immediate rescue operations; however, after over 5 hours of searching, nearby Covenant activity forces the search to be terminated, and Kurt-051 is 'officially' declared MIA. In actuality the operation was a ruse: Kurt is picked up by Colonel James Ackerson and recruited to train his SPARTAN-IIIs.

December

 * December 14: After being extracted by Colonel James Ackerson, Kurt-051 is briefed on the SPARTAN-III project and given leadership over its implementation, as well as a new identity as "Kurt Ambrose".
 * December 19: Nicole-458 is born.
 * December 27: 497 recruits arrive at Camp Currahee on Onyx beginning the Spartan-III program under the command of Kurt-051, forming what will later become Alpha Company.

Other events

 * Spartan-II Blue Team disrupts Insurrectionist activity in Micronesia and breaks up a saboteur ring on Reach between November 2530 and May of this year.
 * Rear Admiral Cole is promoted to admiral upon his return to Earth and learns that a number of outlying colonies have been destroyed, leaving behind no survivors. He begins to move his fleet around, trying to intercept the invaders. Ground and ship-to-ship battles begin in earnest, raging throughout the Outer Colonies.
 * The MJOLNIR Powered Assault Armor/EOD variant enters service.
 * The Assembly takes note of a "third participant" mentioned in the Covenant battle network during the battle for the Shield World, one which caused "irrational terror" for the Covenant. While presenting the possibility of contacting this third faction, they decide not to, due to the risks involved.
 * The Ket-pattern Truth and Reconciliation enters service around this year.