Battle for Arcadia

The Battle for Arcadia was a military engagement fought between the United Nations Space Command and the Covenant on the human colony world of Arcadia during the Human-Covenant War in 2531.

Prelude
Shortly after one of the last battles of the Harvest campaign, Arbiter Ripa 'Moramee and his ships quickly left the system after learning the location of Arcadia from a Forerunner artifact buried under Harvest's north pole. Professor Ellen Anders briefly examined the artifact and learned that it pointed in the direction of another planetary system. At her suggestion, and with permission from Admiral Preston Cole, the  followed the Covenant fleet in hot pursuit.

Space battle
Upon reaching Arcadia, two Covenant s exited slipspace. The arrived soon after. The, , , and engaged the two battlecruisers immediately, catching one of them, designated CCS-U321, with its shields down and destroying it. However, the UNSC force suffered for its part in the battle. The Texas and Belfast were both destroyed, the Armstrong was venting atmosphere due to damage, and the Autumn suffered severe damage. After disabling the remaining UNSC vessels, the second battlecruiser, designated CCS-U624, moved towards Arcadia. Meanwhile, the Autumn and the Armstrong were assisted by the Spirit of Fire.

At some point in the battle, Admiral Preston Cole and his fleet arrived at Arcadia and engaged the Covenant forces. Before the Spirit of Fire left the Procyon system, it dropped a log buoy which Terrence Hood, captain of the, was assigned to recover. However, as the colony was already deemed lost by UNSC command, Roman Blue was also ordered to withhold from engaging the enemy in combat. Hood, enraged by the massive losses the Covenant had already inflicted on humanity, ordered his crew to attack the Radiant Perception. Overwhelmed, Hood was forced to retreat. Consequently, the Spirit of Fire's log buoy was not recovered and Hood would view himself as responsible for the Spirit of Fire's disappearance. The log buoy was recovered by the Radiant Perception, but the ship was shot down on Laconia during the battle. The space engagement ended with the destruction of most Covenant vessels, with the remaining ones fleeing from the system.

Ground battle
"It's a blood bath here! We need some cover now!"

- An Arcadian Patrol officer

Shortly after the first space engagement, the second Covenant vessel, CCS-U624, was engaged in "surface activity" on Arcadia, attacking civilian targets and Pirth City, Arcadia's capital. The Arcadian Patrol, the primary police force of Arcadia, was deployed to counter the Covenant invaders but, being a civilian force, was easily overwhelmed. As the Arcadian Patrol was evacuating civilians in Pirth City's spaceports, Covenant forces began to move in on them in an attempt to deny the civilians' escape. SPARTAN Red Team and forces under the command of Sergeant John Forge assisted in rescuing civilians, evacuating hundreds to several civilian transports abandoning the city. The Covenant, unfortunately, were successful in destroying several of these transports, resulting in massive civilian casualties.

However, despite several repeated assaults, the UNSC was successful in saving at least a portion of the population before being forced to retreat to the city's outskirts, where they were reinforced by SPARTAN Team Omega. Forge's team fortified the outskirts and linked up with several groups of stragglers. These forces, led by the Spartans, teamed up to destroy a Covenant field base, from which the UNSC survivors suffered several assault attempts by the Covenant. After a majority of the Covenant forces were eliminated around Pirth City, Team Omega departed and Forge was ordered to return to the bridge of the Spirit of Fire. During the Covenant's assault on Pirth City, all other major population centers on the planet were discovered and destroyed by Covenant forces.

Following this, the UNSC forces established a base of operations at a deserted ONI base in a jungle on the far side of Arcadia. Anders aboard the Spirit of Fire discovered a massive dome-shaped Covenant energy barrier on the planet. Determined to find out what the Covenant were after, the Spirit of Fire attacked the shield dome with M145D Rhinos supplied by the Pillar of Autumn. The UNSC forces became constantly harassed by Covenant air patrols, but were successful in repelling them. After the shield dome was partially disabled by the Rhinos, the Spirit of Fire barraged the area with several MAC round blasts to take out the shield's generators.

Under the shield dome, the UNSC forces found a series of Forerunner ruins guarded by an incomplete Type-29 "Super" Scarab the Covenant were upgrading with technology from the ruins. The Spirit of Fire's forces then advanced on the Scarab's construction site, taking cover behind the Forerunner ruins as the Scarab fired on them. However, the Scarab was only partially operational and only its "head" was active. After a considerable effort on the part of the UNSC, they destroyed the Scarab and proceeded to investigate the site.

Under orders from the Prophet of Regret, Arbiter Ripa 'Moramee traveled back to Arcadia and captured Professor Ellen Anders while she was investigating the ruins of the Scarab the next day. After a brief fight with Forge, 'Moramee captured Anders and fled the system.

Aftermath
Despite the victory, the UNSC suffered a major setback as it investigated the Forerunner ruins on Arcadia. With Anders captured by Arbiter Ripa 'Moramee, he delivered her to the Prophet of Regret with the intention of using her to unlock the Forerunner dreadnoughts held at the Apex Site. The Spirit of Fire was able to follow his ship to Trove, beginning the Battle of Trove.

After the battle, out of guilt, Captain Hood provided financial support for both Cutter's legitimate family (his apparent widow Mary and their daughter) and his secret one, supporting Daniel Clayton's mother for years.

The UNSC regained control of the planet, but now that its location was known to the Covenant, most of its inhabitants abandoned the colony. A small number of colonists remained, establishing the settlement of Abaskun on the Mu continent, which supplied the UNSC with much-needed foodstuffs until the Covenant returned to the colony in 2549, glassing it.

List of appearances

 * Halo Wars
 * Halo: Reach
 * Dr. Halsey's personal journal
 * Halo: Escalation
 * Halo Mythos
 * Halo: Fractures
 * Into the Fire
 * Halo: Smoke and Shadow
 * Halo Wars 2