Harvest campaign

The Third Battle of Harvest was an engagement during the Human-Covenant War when the Covenant attacked Harvest again in the hope of securing a Forerunner artifact buried under the planet's north pole.

Space Battle

On January 6th, 2531, Admiral Preston Cole received a message from Commander Orez of ONI. Orez informed Cole that the Destroyer UNSC Prophecy had repelled newly arrived Covenant warships in the Epsilon Indi System.

The UNSC Spirit of Fire was chosen by Cole due to it's role as a "support ship" rather than a warship. The Spirit of Fire arrived at the system three days after the Prophecy sent their message.

Upon their arrival, Serina analyzed the Prophecy and reported that the ships nuclear reactor was damaged and was releasing harmful doses of radiation throughout the ship.

Serina also guessed that the ONI Prowler that reported the battle to HQ was present at the time but did not make any attempt to stop it.

The Spirit of Fire attempted to draw the Covenant away from the Prophecy by using its MAC gun and HAVOK Nuclear Warheads upon enemy craft. While it destroyed a number of dropships, they destroyed only one Covenant warship, as the rest gathered behind the Prophecy to prevent being fired upon.

Fire Team Lima, commanded by Sergeant Forge, was transported to the ship, but their Pelican was fired on and made a crash landing on the Prophecy. The landing resulted in the death of Chris and forced the survivors to do a "soft seal entrance": using torches to burn their way into the Prophecy. They then took part in combat with Jackal Rangers, easily dispatching them and losing no forces. The team split up with Lima-One (Forge) heading for the NAV room and the rest of Lima searching for survivors. Serina noted to Forge through his visor that the ships AI "FitzGibbon" may have gone rampant.

Forge was originally denied access to the NAV room by FitzGibbon due to misconduct in his service record. After Forge reminded him of the Covenant borders, FitzGibbon gladly allowed him entrance into the NAV room to purge the data. FitzGibbon then activated a three-minute self-destruct timer and informed Forge his team was in Bay 2.

Upon his arrival at Bay 2, the team quickly evacuated with at least two of the UNSC Prophecy's crew. After arriving back on the Spirit, the survivors were taken to the Med. bay, where Serina informed Forge that the radiation poisoning that the crew sustained was too severe and that they would certainly die.

After the threat in space was destroyed, ONI kidnapped civilian scientist Ellen Anders shortly after a seminar on intelligent life that once existed on the planets Cote D'Azure, Bliss and Onyx. ONI wanted her to decipher a Covenant message written in Forerunner symbols. Anders was then sent to the Spirit of Fire via the UNSC Last Gleaming.

Upon her investigation, she concluded that the message meant that "treasure" (Relics) were to be found, but hidden (from the Humans). Shorty thereafter, Anders scanned the northern polar region of Harvest, concluding that there was a structure under the ice.

Ground Battle

Main article: Battle of the Relic

Sergeant Forge was ordered by Cutter to report to Alpha Base and repair it. Upon Alpha Base's re-entering into service, the growing military presence made an assault on the Covenant defenders of the structure.

Upon capturing the structure, Anders opened up a holographic map of the nearby systems. Several Sangheili disengaged their Active Camouflage and attacked Forge's group. Two Grizzlies were dropped in to help Forge escape from the Spirit of Fire. Upon their safe return to the Spirit, the ship left the system to follow what Anders had discovered inside the forerunner station

Aftermath

The information gained by the Covenant from the Forerunner structure led them to the UNSC colony Arcadia. Anders was drawn to the same planet after examining the artifact. The Covenant attacked Arcadia on February 9th, 2531, and the Spirit of Fire followed.