Battle of Installation 05
From Halopedia, the Halo wiki
The Battle of Installation 05, also known as the Battle of Delta Halo, was a major engagement between the United Nations Space Command, Covenant, Sentinels, and the Flood on the Forerunner ringworld Installation 05, otherwise known as "Delta Halo".
Introduction
During the First Battle of Earth, the Prophet of Regret lead a small fleet of two Assault Carriers and thirteen CCS-class Battlecruisers on an expeditionary raid that stumbled upon Earth, the strongest UNSC stronghold planet. After substantial ground, air, and space losses, Regret fled in an Assault Carrier over New Mombasa, opening a Slipspace rift and destroying the city in a devastating Slipspace cataclysm as it initiated an emergency jump to Installation 05, although how the Covenant obtained the coordinates to Installation 05 were unknown.
However, five United Nations Space Command Defense Force warships were close enough to catch onto the Assault Carrier's rift before it terminated: three UNSC Frigates, the UNSC In Amber Clad, UNSC Paris, and the UNSC Redoubtable, one UNSC Corvette, the UNSC Coral Sea, and one UNSC Prowler, the UNSC Dusk, were able to enter the Slipspace field, trailing the Assault Carrier.
