2540

May

 * May 9: Lieutenant Commander Fhajad-084 published an article on slipspace physics that was featured within the later UNSC Astrophysics Journal 034-23-01. This paper was used 12 years later in 2552 by at the time Commander Jacob Keyes when he realized Covenant warships were inbound for Sigma Octanus IV.

September

 * September 9: Taylor "Dutch" Miles enlists in the UNSC Marine Corps.

Unknown

 * Around his sixth birthday on July 5, Gabriel Thorne moves to the city of New Phoenix to live with his grandparents.