- February 4, 2531: the Harvest Campaign ends with a UNSC victory and the Spirit of Fire is tasked with setting up bases on the surface and driving the Covenant from Harvest. Investigation of a Forerunner relic on Harvest urges the Spirit of Fire to presume their campaign off world in pursuit of the Covenant.
- February 9, 2531: the UNSC Spirit of Fire arrives at Arcadia to lend Spartan-II Red Team a hand in evacuations. Prof. Ellen Anders is captured by the Covenant and the Spirit of Fire follows again in pursuit.
- February 23, 2531: the Battle of Shield World 0459 begins. The Spirit of Fire destroy the alien world and escape into unknown space without an engine. The crew are listed as MIA.
- October 24, 2531: Colonel James Ackerson proposed the Spartan-III Program to the Office of Naval Intelligence.
- December 27, 2531: 497 recruits arrive at Onyx to begin the Spartan-III Program as Alpha Company, but only 300 maximum are selected.
- 2531: the Covenant glass Verent.
- 2531: renowned institutes and organizations offer to integrate Thornhill Research Institute International into their own. Although these opportunities offer lots of money, Lucius Thornhill refuses to hand TRI over to someone else. Instead, he establishes a partnership with Eastman Research Association. ERA grants TRI access to more advanced alien technology that needs decoding and understanding.