From Halopedia, the Halo wiki
- May 28: Atriox is born.
- August 8: Dr. Catherine Halsey makes the first entry in her journal following her enlistment in ONI's service and arrival on Reach.
- August 15: Thomas Lasky is born in Tricode Village, Mare Erythraeum on Mars.
- August 22: Edward Buck is born in New Albany, Lombard, on Draco III.
- December 1: The UNSC Pillar of Autumn is commissioned into service.
- December 15: Carris-137 is born in Irbid, Tribute in the Epsilon Eridani System.
- Between 2510 and 2511, the future candidates for the SPARTAN-II program are born.
- The Mark III exoskeleton is introduced. It is retired the following year, with the Office of Naval Intelligence's Materials Group pursuing Project: MJOLNIR instead.
- The structural system of the Halcyon-class light cruiser is designed by Dr. Robert McLees.