A timeline of all major events in the Halo universe from the time of the Forerunners through the rule of the Created.
The Battle of Installation 00 was a major conflict between the forces stationed aboard the UNSC Forward Unto Dawn and Arbiter Thel 'Vadam's Fleet of Retribution, and the Covenant fleet loyal to the Prophet of Truth.
~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.
~97,495 BCE
The release of the Primordial was an unintended consequence of the test-firing of a Senescent Halo, Installation 07, by the Master Builder and Mendicant Bias in the Charum Hakkor system during the Forerunner-Flood War, approximately fifty years prior to the end of the war and the Great Purification.
~97,454 BCE
The Fate of Maethrillian was a large-scale but brief battle between the Forerunners and the Halo Array under command of Mendicant Bias several years prior to the firing of the halos during the Great Purification in 97,445 BCE.
~97,454 BCE
In the aftermath of the Fate of Maethrillian and destruction of the Forerunner ecumene, Zeta Halo implemented it’s security measure designed to prevent the ring from falling into enemy hands and performed a slipspace jump into another system and put itself on a collision course with a nearby planet.
~97,445 BCE
The Battle of the Greater Ark was one of the final battles of the Forerunner-Flood War and saw the decimation of almost all remaining Forerunner forces just prior to the firing of the Halo Array during the Great Purification in 97,445 BCE.
