Arcadia

Arcadia was part of the Outer Colonies of human influence, located in the Procyon system.

The Forerunners
Arcadia was once a heavily populated Forerunner colony. Following the activation of the Halo Array, the remnants of the Forerunners' presence on the planet were destroyed by erosion or buried deep beneath Arcadia's surface. One Forerunner ruins, a building complex, became a site of conflict in 2531.

Human colonization
Upon humanity's discovery of Arcadia, the planet was found to have no need for terraforming, as it was already inhabited by dense jungles and large oceans. Arcadia was rich in natural resources. Almost no change was made to its geographical features. The largest landmasses were established as six continents; Eire; Pacifica; Mu; Caledonia; Lemuria and Avalon. Humanity first colonized Arcadia in 2429. Pirth City, in Mu, became the largest city on the planet and the capital city of the planet; other major cities on the planet included Abaskun, Daylam and Saqsin. The planet was home to three space elevators. Arcadia's population and structures were all very clustered, leaving huge areas of the planet unexplored.

Arcadia became a center for agriculture, research and recreational activities. It was also home to the Deep Space Research Array. Among other exports, the planet was known for a good vintage of champagne. The planet's police force was known as the Arcadian Patrol.

Arcadia was a center of Insurrectionist activity in the 2520s, during which the ODSTs saw combat against them. Among these ODSTs was Cadmon Lasky, brother of Thomas Lasky.

Human-Covenant War
By 2531, Arcadia had a population of approximately three million. In February 2531, Arcadia was invaded by the Covenant after a Forerunner stellar map on Harvest pointed Arbiter Ripa 'Moramee toward the colony. Eventually, the Covenant were pushed off by the efforts of the crew of the, as well as SPARTAN teams Red and Omega, allowing much of its civilian populace to be evacuated.

After the evacuation of the planet, the capital city of Pirth was soon overtaken by nature. Meanwhile, the remaining colonists formed the farming community of Abaskun on the continent of Mu. It would remain a mostly lawless region, but continued to supply the UNSC with food. The Covenant would return to Arcadia later in 2549, glassing it.

Post-Covenant War
By 2556, what remained of Arcadia had become home to multiple salvage operations undertaken by Kig-Yar. The United Nations Space Command, in response, launched Operation: MAD HATTER, which not only involved the surveillance of these activities but also the mapping of new potential slipspace routes to and from the planet. Spartan Jameson Locke participated in Operation: MAD HATTER.

Main continents

 * Eire
 * Pacifica
 * Mu
 * Abaskun
 * Pirth City
 * Caledonia
 * Lemuria
 * Avalon

Other locations

 * Deep Space Research Array - A research facility on Arcadia.
 * Fort Deen
 * ONI base - An ONI facility in Arcadia's jungles.
 * Forerunner ruins - A complex of Forerunner ruins near the ONI base.
 * Orbital refinery complex - an orbital platform destroyed during the first Covenant attack.
 * Daylam and Saqsin, two major cities on Arcadia.

Trivia

 * The planet may have been named after Arcadia, a region and city south of Greece in the Peloponnesus. It was more likely named after the utopia of the same name from Greek mythology, given the planet's nature as a resort world.
 * Arcadia's continents and many other planetside locations receive their names from islands and continents of mythology, ancient Earth cities, as well as the ancient names of Earth locations.
 * The original idea for Arcadia was pitched to Joseph Staten by Graeme Devine, the lead designer of Halo Wars. Staten liked the idea so much that he mentioned it in his novel Halo: Contact Harvest.
 * The water in the jungles of Arcadia likely contains many bacteria and protists that cause disease, as Cadmon Lasky contracted diarrhea after drinking a mouthful of river water.
 * Arcadia is the setting for the RISK: Halo Wars Collector's Edition board game.
 * In the Halo Encyclopedia, Arcadia is erroneously referred to as an Inner Colony on page 286.

List of appearances

 * Halo: Contact Harvest
 * Halo Wars
 * Halo Legends
 * Origins
 * Halo: Reach
 * Dr. Halsey's personal journal
 * Halo 4: Forward Unto Dawn
 * Halo: Escalation
 * Halo 5: Guardians
 * Limited Edition