POPULATION: 0
SPECIES: N/A
ANCIENT HISTORY
Delta Halo, formally Installation 05, was the fifth Halo built for the Neoteric Halo Array. It orbits the gas giant Substance, which is in turn orbiting the star Coelest in the Norma Arm of the Milky Way galaxy. At the tail end of the Forerunner-Flood War in 97,445 BCE, Delta Halo was fired for the only time as part of the Great Purification that cleansed the galaxy of all sentient life and eliminated the Flood threat.
Sometime prior to the halo's discovery by the Covenant, likely thousands of years beforehand, the Flood being studied on the facility escaped containment, establishing a Gravemind and creating a significant threat to all life on the ring and anyone who landed on the surface.
~97,745 BCE - 97,445 BCE
The Forerunner-Flood War was a military engagement between the Forerunner species and the Flood that took place over approximately three-hundred years from 97,745 BCE until 97,445 BCE.
~97,445 BCE
The Great Purification was the final event of the Forerunner-Flood War, purging the entire Milky Way galaxy of all sentient life, including Forerunners, the Flood, and any other species that may have survived the Flood infestation.
MODERN HISTORY
The ring was visited by the Covenant in 2552 during the Battle for Earth, who were attempting to fire the array to begin the Great Journey. UNSC forces followed the Covenant, successfully stopping the firing of the halo, though not before placing the entire array in standby. Following the Battle of Installation 05, the Forerunner construct was left alone, though the UNSC placed a space station in orbit around the halo to keep tabs on its status and study it prior to decommissioning.
The Battle of Installation 05 was an engagement between the Covenant forces, including those that fled the Battle for Earth, High Charity, and the Second Fleet of Homogeneous Clarity, and the UNSC-allied forces, including the UNSC In Amber Clad led by Miranda Keyes, and the Fleet of Retribution led by the Arbiter Thel 'Vadam.