2546

Prior to September

 * Sargasso is invaded by the Covenant. The Type-46 Infantry Support Vehicle is first encountered by United Nations Space Command personnel during the battle.

September

 * September 21: Led by Edward Buck, Alpha-Nine conducts a military operation against the Covenant on the colony of Sargasso.

Unknown

 * New Llanelli is attacked by the Covenant, who are victorious and glass the planet.
 * Lydus, a Jiralhanae Chieftain, is recorded to have left the Oth Sonin system for the first time.