Halo 4's billion year secret: The full Halo timeline

A complete timeline of the sci-fi series, and what it all means for Halo 4...

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When 343 Industries revealed the first in-game footage from Halo 4, shortly before March's Game Developers Conference, they did it a little too quietly.

Franchise director Frank O'Connor, creative director Josh Holmes, and incredi-named executive producer Kiki Wolfkill rolled their tape, sat back, and refused to say anything concrete about the game. The footage, they assumed, speaks for itself - and it does, but only in the context of a billion years' worth of Halo history.

Bungie's own in-game timeline didn't always tally with Microsoft's licensed novels and comics, so when Bungie bought independence with ODST, Reach, and a truck full of money Microsoft turned to one company − 343 Industries − totake full control of the Halo universe, extended or otherwise.

343 Industries handle Halo's Waypoint website and app, produced the Halo Legends animated shorts, published three novels, and managed Sabre's Combat Evolved remake. Under Bungie and Microsoft the Halo timeline was malleable, but for 343it's set in stone. Halo's extended universe is informing everything about Halo 4, from its setting on a Forerunner Shield World to the enemies drawn from a point 100,000 years in the past. Halo 4's protagonists were first introduced inthe pages of Primordium and Cryptum and its new technologies debuted in Glasslands.

Catching up with it all could take a while, so we've done the hard work for you, pulling together threads from every piece of Halo fiction and ironing out the contradictions for adefinitive wrap-up of one billion years of fiction. We then tell you what it all means for Halo 4.

1,000,000,000 - 150,000 BC

  • The Precursors are the pre-eminent species in thegalaxy, moving beyond sentience into practical godhood. They can traverse galaxies in seconds, control evolution and create life.
  • The Precursors seed the Milky Way with life, looking toraise a species worthy of carrying on their stewardship ofthe galaxy.
  • The Precursors create the Forerunners and look to elevate them to rule the galaxy, but eventually deem them unworthy of the role. They also create humans.
  • The Forerunners go to war with the Precursors.
  • The Precursors create the Flood as a final test for both first generation humanity and Forerunners.
  • The Precursors are annihilated by the Forerunners. It isn't clear exactly how this happens.


  • Forerunners have colonised much of the Milky Way thanks to Precursor technology. They are a now peaceful race and help elevate undeveloped races.
  • The first generation of humans begins colonising the galaxy using more technology left over from the Precursor era. Their civilisation grows to rival that ofthe Forerunners.


  • Humanity and the Prophets make first contact with the Flood and go to war.
  • Humanity retreats into Forerunner space and the Forerunners strike back.

109,000 BC

  • Forerunner general The Didact leads his people to victory against humanity. Humanity is devolved into several different species and its colonies are destroyed.
  • Unbeknownst to the Forerunners, the human/Prophet alliance had successfully driven the few surviving Flood from the galaxy at the expense of victory against the Forerunners.

Who is... The Didact?


A Forerunner Promethean and the leader of the Forerunner military, the Didact lead his people to victory against humanity, but was imprisoned for his opposition of the Halo array. His original body was killed in 100,000 BC, and his consciousness found a new home in the body of Forerunner Manipular Bornstellar. The Didact once again took control of the military in the Flood/Forerunner war but his plans for fighting the Flood were rejected by the Forerunners' council, leaving only one option when Mendicant Bias broke their defensive line. His whereabouts after firing the array are unknown.

Certainly, the Didact survived the firing of the Halos. In his final transmission he tells the Librarian "I will begin our Great Journey without you,carrying this bitter record" - presumably, we suspect, joining the last of the Forerunners on their voyage out of the galaxy rather than taking the Covenant's version of the 'Great Journey' and dying with everyone else. The Didact and his armies will play a key role in Halo 4, but whether as friend or foeisn't clear.

Now residing in Bornstellar's Builder-class body, the Didact would lack the four metre-tall, 1,000 kilo body he had as a Promethean. In one of Halo Anniversary's Terminal videos, Guilty Spark remarks: "what I would not give to have a single company of Prometheans here. They would restore order with their trademark lethality, although... that would mean he would have to be here, too. And without the Librarian around to temper his rage, well... These Reclaimers might almost prefer the Flood."

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