Keyship



The Keyship is a classification of supra-luminal Forerunner naval vessel in use at the time of the Forerunner-Flood War.

Mentioned only in the hidden Terminals found on the Ark and second Installation 04, Keyships were a class of Forerunner vessel capable of activating portals leading to the Ark. They were capable of remote detonation to prevent their usage by the Flood. Though many more once existed, the majority were destroyed by the Librarian to prevent the Flood from reaching the Ark.

History
During the Forerunner-Flood War, there was an entire fleet of Keyships. It was used extensively by the Forerunners in their war against the Flood. A number of Keyships were given to the Librarian, and combined with her ability to build Portals, the Librarian was able to transport herself back to the Ark with her Keyships if the situation required. The Librarian, however, bravely destroyed her Keyships to prevent them from falling into the hands of the Flood, who with them, would be able to instantaneously travel to the Ark, rendering the Halo Array useless. Near the end of the war, the Keyships were part of an unknown strategy to hold off the Flood for nearly 79 years, although this advantage would be foiled by the massive computing power of the Flood. At the Battle of the Maginot Sphere, Didact was in command of multiple Keyships, although near the end, when the Forerunners began generating Slipspace ruptures to destabilize the battlefield and destroy Flood craft, Keyships were recklessly piloted near the rifts, destroying them.

The few remaining vessels were launched from Installation 00 after the seven ringworlds fired out their pulses, destroying all sentient life. These contained the Forerunner's collection of sentient specimens, one ship for each planet's peoples. The rogue Forerunner AI "Mendicant Bias" would find his way onboard a Keyship delivering the San 'Shyuum back to their homeworld.

By 2552, that particular vessel, commonly referred to as the Forerunner Dreadnought, was most probably one of, if not the last surviving Forerunner Keyship in existence, used by the Covenant for an unknown amount of time as an unusual source of power for their holy city, High Charity. At the end of the Ninth Age of Reclamation, the Prophet of Truth appropriated the dreadnought to activate the Portal on Earth and travel to Installation 00. It was last known to have gone to ground on said Installation, and is believed to have been destroyed upon the premature activation of Installation 04B.

Keyships the Key to Repopulation
While speculation on the Keyships use during the Forerunner- Flood war as a common battleship in the Forerunner fleet is semi-legitimate, only one use by the Forerunners can be assured and confirmed through the Halo: Legends short entitled Origins. In this film Cortana tells the story of the Forerunner-Flood war incorporating detailed images of Forerunner battle techniques used against the flood, including showing several battleships, none of which included Keyships.

In Cortana's explanation the Keyships are shown to be the Forerunners "insurance policy" for sentient life. She shows that the Forerunners gathered DNA and living specimens of the notable sentient species located throughout the galaxy and protected them from the devastation of the Flood and all other life via Halo. The Keyships were then sent to the planets from which the sentient species were eliminated and cloned and released a population of the species on their planet of origin. These ships therefore were not a vessel of war, but rather specifically designed to reinstate life on the planets devastated by Halo.