~97,745 BCE - 97,445 BCE

The Forerunner-Flood War was a military engagement between the Forerunner species and the Flood that took place over approximately three-hundred years from 97,745 BCE until 97,445 BCE.

~97,445 BCE

The Great Purification was the final event of the Forerunner-Flood War, purging the entire Milky Way galaxy of all sentient life, including Forerunners, the Flood, and any other species that may have survived the Flood infestation.