AVERAGE SIZE: 6.5 - 13.5 feet, 250 - 830 lbs
AVERAGE LIFESPAN: > 1,000 years
COMMON NAME: Forerunners
For well over ten million years, the Forerunners were the dominant species in the Milky Way galaxy. Created by the Precursors fifteen million years ago, the Forerunners were intended to ascending to the Mantle of Responsibility, only to be found lacking five million years later. The Forerunners, having learned of the Precursor’s plan to remove the Forerunners and replace them with another species, decided their only option was to fight back and eradicate the Precursors instead. Though the Precursors were technologically superior, the Forerunners were still able to defeat them, either through luck, skill, or because the Precursors allowed them to.
Nearly ten million years later, around 100,000 BCE, the Forerunners were threatened again by ancient humanity encroaching on their territory as they ran themselves from the encroaching Flood, and feeling threatened by humans, retaliated and began the Human-Forerunner Wars. Though the Forerunners were far more advanced, the human race nearly won the war, but they were eventually defeated at their stronghold of Charum Hakkor. As punishment, they devolved humanity but allowed their civilization to grow again back on their homeworld of Erde Tyrene.
Worried of the threat the Flood posed were it to return to the galaxy, Forerunner leadership began two different projects aimed at protecting the Forerunners from the Flood, the shield world system and the Halo Array. The shield world plan, favored by the Didact, was to build hundreds of hidden and protected worlds that would keep the Forerunner populations safe and provide a staging ground for counterattacks on the Flood. The Halo Array, meanwhile, was an offensive weapon championed by the Master Builder, designed to wipe out all sapient life within the pulse radius of a Halo, which initially only spanned an entire solar system. It was only later that the Forerunners turned the Halo Array into a true galaxy-spanning doomsday weapon.
When the Flood reappeared in the galaxy in 97,745 BCE, the Forerunners attempted to fight back, but quickly lost many of their three million colony worlds. Around fifty years prior to the end of the three-hundred year war, the ancient precursor known as the Primordial gained access to the ancilla in charge of Forerunner defense and the Halo Array, Mendicant Bias, and corrupted it using what is referred to as the logic plague. Using Mendicant Bias against the Forerunners, the Primordial and the Flood hastened the end of the Forerunners considerably, forcing them into a near constant retreat as system after system fell to the Flood.
In 97,445 BCE, the Forerunner civilization officially ended. Having been forced back to their last stronghold at the Greater Ark, the Forerunners put up one last defense against the Flood, but their sheer strength and use of Precursor star roads put a swift end to what was left of the Forerunner military and civilization. A very small few managed to escape the battle to the Lesser Ark, where control of the galaxy-killing Neoteric Halo Array was located. With Flood approaching their location and the rest of the formerly Forerunner-controlled galaxy lost, the Halo Array was activated, wiping out the Flood and all sapient life in the galaxy.
The galaxy recovered for the next 100,000 years following the firing of the Halo Array without the Forerunners, thanks to the Librarian’s Conservation Measure. Although nearly every known Forerunner had either been killed or left the galaxy, the remnants of their technology remained, which became objects of worship by what would eventually become the Covenant. This became of particular importance during and at the end of the Human-Covenant War in 2552, when a few of the Halos and soon after the Ark were discovered and attempted to be activated again.
Following the war, one of the shield worlds, Requiem, was discovered and the former head of the Forerunner military during the Human-Forerunner Wars, the Ur-Didact, was found alive in stasis in a cryptum. He was released, and though he made every effort to finish what he started by composing the entire human race, he was thwarted in 2557 through the combined efforts of John-117 and the remaining essence of the Librarian.
With many of the formerly dormant Forerunner artifacts having been found and activated in the years after the war ended, the galaxy became a much less stable place. This notably came to a head when the human AI formerly assigned to the Master Chief, Cortana, was inadvertently sent to the Forerunner hub world of Genesis at the end of the fighting with the Ur-Didact and made contact with the Domain. Though motivations are still unclear, Cortana was able to use the Domain to extend her life beyond the normal seven years and took command of Forerunner peacekeeping constructs known as Guardians, using them to make the entire known galaxy subservient to her and her fellow AIs known as the Created.