Operation: BIRD IN HAND

The raid on Argent Moon was an attempt by the United Nations Space Command to recapture the occupied Office of Naval Intelligence research and development space station Argent Moon. Spartan-II Blue Team was deployed to eliminate all hostiles and reclaim the vessel.

Background
Argent Moon was a research and development vessel for the Office of Naval Intelligence. After nine of study in space, the ship crew's was wiped out by one of their chemical weapons gone wrong. Although shipboard smart AI Rooker attempted to enforce quarantine protocols, they massively failed and all personnel aboard Argent Moon were dead by March 17, 2557. Rooker then took further measures to quarantine the ship, piloted it to a remote asteroid belt to keep it away from an inhabited systems. After six months, Rooker began suffering from rampancy and self-terminated, leaving the vessel empty. The abandoned starship was found more than a year later by Kig-Yar pirates, who sold it to Jul 'Mdama's Covenant. As his soldiers started tearing up the vessel for supplies to use in their war against the Swords of Sanghelios, ONI was alerted to the ship's discovery and ordered Spartan Blue Team to storm and reclaim it.

Storming
On October 24, 2558, Blue Team was sent by Pelican to the asteroid belt where Argent Moon lay. Leaving their Pelican and traveling by EVA, Blue Team made it into the ship and immediately began encountering Covenant forces. Blue Team fought their way to the ship's data center. Blue Team's initial plan was to fight their way to Central Control, where they could take command of the Argent Moon, shut off its gravity and life support systems, and so flush out its decks of any remaining hostiles. Rescue of any remaining ONI personnel was also a priority, but a scan of the ship at the data center indicated that none of the original crew had survived.

Making their way to an assembly bay, Blue Team engaged a large contingent of Covenant forces primarily composed of Unggoy and Kig-Yar Rangers. Clearing out all Covenant present, the Spartans made it through the bay. Blue Team was almost at Central Control's location when they were ambushed by a pair of Mgalekgolo, who broke the catwalk they were on, sending them down to the maintenance tunnels several stories below. At the bottom, Blue Leader John-117 had a vision of a seemingly-alive Cortana, urging him to follow her to Meridian. When he came to, he informed Blue Team of the vision and they resolved to discuss it afterward. The Spartans followed their map's directions to an elevator that would take them back to the top decks. But reaching it required going four levels even lower in the ship. In these dark corridors, Blue Team encountered numerous suicide Unggoy as well as cloaked Sangheili, many of whom were Zealots. Additionally, the Mgalekgolo pair were following them in the tunnels, hoping to cut off and confront the Spartans sooner or later.

The scuttle
As Blue Team reached the third level, they received reports lighting up the Covenant battle network and witnessed numerous Covenant starships exiting slipspace. With no chance of reclaiming Argent Moon against a numerically superior alien force, John changed the team's objective from capture to asset denial. Their plan now was to head to the ship's reactor and shut off its safeties so the reactor would overheat and detonate, destroying the ship, the Covenant aboard, and any Covenant warships surrounding it.

Blue Team continued lower in the ship to reach the reactor, and on the way, encountered the Mgalekgolo pair, ambushing them in a lab. Many more Covenant troops were defending the ship's reactor. After fighting and killing them all, Blue Team deactivated the reactor's failsafe for its overload. However, Argent Moon responded with automatic safeties, moving the reactor to a cooling center where it could be contained. To ensure its overload, Blue Team followed the reactor to the cooling center in vacuum, using Banshees to destroy its coolant pipes. With their interference, the cooling system failed and the reactor began overheating, prepping Argent Moon's destruction.

Escape
Blue Team needed to escape, but their Banshees would not escape the explosion in time and their arrival Pelican appeared to have been destroyed. John thus ordered them to the hangar where they could take a Winter-class prowler and escape into slipspace. Arrived at a hangar, the Spartans found the parked ONI Acrisius, but needed to recharge its fuel cells. A huge Covenant force, including another Mgalekgolo pair and numerous fuel rod cannon-wielding Unggoy attacked the Spartans, forcing them to defend themselves, waiting for the Prowler to prep for launch.

With the hangar cleared and Acrisius ready, John-117 radioed the UNSC Infinity and informed them that he would be sending Blue Team to Meridian. However, Infinity was mysteriously already aware of Cortana's return and ordered John back to them while another Spartan team was sent to deal with her. Rejecting their orders, John and Blue Team chose to go AWOL and evacuated aboard Acrisius, leaving Argent Moon as it exploded and killed all the Covenant in its vicinity.

List of appearances

 * Halo 5: Guardians
 * Halo Mythos