2543

2543 was a year in the 2540s in the 26th century.

February
February
 * Preston Cole records his final entry in his personal log.

March
March 6 March 9 March 18
 * The Battle of 18 Scorpii takes place. UNSC forces are saved by Insurrectionists.
 * Vice Admiral Preston Cole contacts Admiral Dale Kilkin at UNSC Central Command Reach Logistics Office requesting a series of requisitions, transfers and favors.
 * Dr. Catherine Halsey finds her journal after it being lost for almost 6 years.

April
April 11 April 18
 * The Battle of Psi Serpentis starts with 's reconnaissance.
 * The Battle of Psi Serpentis, later known as Admiral Cole's Last Stand, takes place.

Summer
Summer of 2542
 * The is assigned to the planet Reach.

July
July 28
 * A day of mourning is proclaimed by the UNSC following the apparent death of Admiral Cole.