97,445 BCE

In approximately 100,000 BCE, the Forerunner-Flood war came to a close. It should be noted that all of the events listed here are approximate at best, occurring somewhere circa 100,000 BCE but most likely not within that exact year.

• The Librarian visits the primary San 'Shyuum quarantine world Janjur Qom to collect specimens of the San 'Shyuum as part of the Conservation Measure, sparking unrest among the San 'Shyuum population. After Master Builder Faber arrives some time afterward to question the San 'Shyuum elders about the Flood, the San' Shyuum rebel against his forces.

• The Didact is resuscitated from his exile in a Cryptum by Bornstellar Makes Eternal Lasting, Chakas and Riser. They later make their way to Janjur Qom, where they are captured by Master Builder Faber. The Didact is interrogated and left to die in a Flood-infested system, while an offshoot of his consciousness lives on in Bornstellar's body through an imprint acquired in his mutation.

• Shortly afterward, the Master Builder orders the Contender-class ancilla 05-032 Mendicant Bias to use Installation 07 to put down the San 'Shyuum rebellion by sterilizing the entire system.

• As a result of the Master Builder's activation of the Halo ring, many Lifeworkers and Warrior-Servants on Installation 07 rebel against his forces, but are mostly defeated.

• A crisis occurs in the Ecumene Council due to the Master Builder's unauthorized activation of Installation 07; many councilors resign in protest while younger ones take their place. Faber is arrested and placed on trial in the Forerunner capital. Eleven of the Halos are brought to the capital, awaiting a decision to have them decommissioned. Installation 07 and Mendicant Bias remain missing.

• During Faber's tribunal, Mendicant Bias, convinced to turn against its masters by the Primordial, brings Installation 07 to the capital system and launches an assault on the Forerunner government. While the Council's fleets respond to the attack and several of the Halos are destroyed, Mendicant successfully fires Installation 07 before the Halo is forced to retreat into a system near the galaxy's edges.

• Having survived Mendicant Bias' attack on the capital, Bornstellar, Glory of a Far Dawn and Splendid Dust of Ancient Suns arrive at the greater Ark, where they are healed by the Lifeworkers. As most Forerunners believe the original Didact to be dead, the Didact's consciousness takes control of Bornstellar in order to assume command of Forerunner military forces after a thousand years of exile and continue his mission against the Flood.

• Shortly afterward, Bornstellar-Didact and his fleet track down Installation 07. The rogue Mendicant Bias fragment on the ring is successfully deactivated and forced to undergo a process to "correct" its rampancy. Although Installation 07 takes heavy damage, it survives and is transported to the greater Ark. The Primordial is imprisoned once again, and is interrogated - and eventually executed - by the Didact.

• After Installation 07 is retaken, the mind of a mortally wounded Chakas is used as the template for the monitor 343 Guilty Spark, which is at first assigned to serve the Librarian and later divided into several fragments, one of which is assigned as the caretaker of Installation 04.

• The Ecumene Council is reconstituted and the Didact's plans of a strategy to use shield worlds to combat the Flood are taken into serious consideration again. The use of the Halos is delayed.

• As the Forerunner-Flood war progresses, the Flood relentlessly continues to push the Forerunners back. In the final hours of the war, the Forerunners realize that activating their last resort, the Halo Array, is the only way to stop the Flood from overrunning the galaxy. The Ecumene Council issues its final dictum and the seven remaining Halo rings are distributed across the galaxy.

• As the Didact prepares to activate the rings, Mendicant Bias assembles all Flood-controlled vessels into a fleet of 4.8 million ships, and breaches the Maginot Sphere. On the other side awaits Offensive Bias and its combined fleet. As the two fleets engage each other in an enormous naval battle, the Halo Array is fired. The Halo pulse kills all sentient life within three radii of the galactic center, including any Forerunners not located on The Ark or within Shield Worlds. Minutes after the firing of the Array, Mendicant Bias's fleet is decimated by Offensive Bias.

• Some time after every sentient species, carefully indexed in the Ark, is returned to their homeworlds as a part of the Conservation Measure, the Homo sapiens species begins migrating out of Africa.

Trivia

343 Guilty Spark put the date of the firing of the Array as the year 97,448 BCE, though it should be noted that he measured it on Installation 04's year, not the 365.25 day Earth calendar.