The Battle of the Alpha Halo occurred at Installation 04. Master Chief and a crew led by Captain Keyes crashed on this uncharted ringworld while aboard the UNSC Pillar of Autumn. They were attempting to flee from Reach, only they encountered a much more dangerous situation. On Installation 04, humans made first contact with the Flood, a parasitic species which destroyed the makers of the installation, the Forerunners.
Master Chief was the primary actor in this battle. Master Chief rescued Captain Keyes who had been taken prisoner on the Covenant frigate The Truth and Reconcilliation. Afterwards, Captain Keyes became infected, and Master Chief was forced to return to The Truth and Reconciliation for another attempted rescue. Unfortunately, Keyes had already been absorbed into the proto-Gravemind. Eventually, Master Chief was able to use the Pillar of Autumn’s fusion reaction to destroy the Halo while escaping on a Longsword fighter.
The Covenant’s defeat at Installation 04 resulted in Thel ‘Vadamee being stripped of his rank and disgraced. He became The Arbiter to redeem himself.
HALOBANANAS 