Operation: PROMETHEUS

Operation: PROMETHEUS was a high-risk mission ordered by the Office of Naval Intelligence. The mission took place on K7-49, an asteroid which served as a Covenant shipyard.

Prelude
K7-49 was discovered when the prowler managed to attach a telemetry probe to an enemy ship during the Battle of New Harmony. The UNSC discovered the asteroid after the ship's return there along with a dozen partially constructed Covenant ships and an orbital shipyard. The asteroid's apparent volcanism was artificial; it was created by high-output plasma reactors that liquefied metallurgical components. These were then refined, shaped, and shipped away for final assembly.

The mission for the SPARTAN-IIIs was to disable as many reactors as possible so that the liquid contents of the facility would solidify and permanently clog the machines, ruining the Covenant's capacity to produce the metal.

The operation
At 0700, 300 SPARTAN-IIIs from Alpha Company landed. Initial resistance to the SPARTANs was light, and after two days, seven reactors had been deactivated before the Covenant organized a proper counterforce. However, the force was neutralized and over the next three days, Alpha Company destroyed 13 more reactors.

However, the Covenant soon arranged a massive counterforce, with the Spartans trading fire with Sangheili and Type-26 Banshees. On the seventh day, more Covenant reinforcements arrived. The Spartans lost their unit cohesion in the battle, while the Elites took up superior positions with good cover. By then, 89% of the planet had cooled, enough for the Covenant shipyard to be shut down. The Spartans, however, were cut off from their Calypso exfiltration craft, preventing them from escaping.

Aftermath
Although the mission was a success and K7-49 would no longer be able to build ships, all three hundred members of Alpha Company were killed in the fighting (other than those transferred out of the company beforehand by Franklin Mendez). According to Kurt-051, if the operation had failed, the Covenant would have destroyed all of humanity's Orion-side colonies.

Timeline

 * On July 27, at 0700, 300 SPARTAN-IIIs land on K7-49.
 * On July 29, seven reactors had been disabled. A counterforce had been arranged by the Covenant.
 * The Covenant force is neutralized. Over the next three days, 13 more reactors are destroyed. A massive attack force has been sent by the Covenant.
 * On August 2, additional Covenant reinforcements arrive. The asteroid has cooled enough for the ship-building operation to be canceled. Alpha Company was cut off from their extraction craft, preventing escape, and causing the deaths of all but three.

Trivia

 * Not all members of Alpha Company were killed in the battle. Many members were transferred shortly beforehand, including Carter-A259, Emile-A239, and Jun-A266, who served with Noble Team as of August 2552.
 * The operation is an obvious allusion to the Battle of Thermopylae. 300 Spartans were present at both battles, both were suicide missions, both were fought in order to slow the enemy down enough for the respective sides to prepare and survive longer, and both resulted in the deaths of nearly all the Spartan combatants.
 * The operation was likely named for Prometheus of ancient Greek mythology, a Titan and champion of mankind who stole fire from Zeus and gave it to humanity.

List of appearances

 * Halo: Ghosts of Onyx
 * Halo Mythos: A Guide to the Story of Halo