101,000 BCE


 * The Forerunner Prometheans, opposed to the construction of the Halo Array, lose their political battle against an extreme faction of the Builders led by the Master Builder, Faber, and are forced out of the Council. Many are disgraced or executed while others choose the alternative of exile in a Cryptum. For the next thousand years, the Council continues to marginalize and diminish the role of the entire Warrior-Servant rate.


 * The Didact enters his first, thousand-year exile in a Cryptum on Nomdagro. The Cryptum is later secretly moved to Erde-Tyrene by the Librarian.


 * The Deep Reverence is retired near Janjur Qom, under the care of the Confirmer.


 * With the final obstacle to his plan removed, Faber commissions the construction of the original twelve Halo rings from the guild of Bornstellar's father.


 * Growth-Through-Trial-of-Change decides to become a Lifeworker instead of a Builder. She is rejected by her family as a result, and is adopted by a foster family.