2509

2509 was a year in the 2500s in the 26th century.

Unknown

 * By this year, many rebel cells had combined under the leadership of Robert Watts, proudly referring to themselves at the United Rebel Front.
 * The M850 Grizzly enters service with the UNSC.

Circa 2509
These are events that are based around this year, and may not fall on this year specifically. Two years after Catherine Halsey met Elias Carver
 * Dr. Elias Carver commits suicide.