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Doisac, designated CE-75-2113 c by the Forerunners, is the third planet of the Oth Sonin system and the homeworld of the Jiralhanae. The planet possesses three natural satellites, Warial, Soirapt, and Teash.
Because of its harsh environmental conditions, numerous predators evolved on Doisac throughout its history, among them the initially arboreal Jiralhanae. Doisac was visited by the Forerunners during the Lifeworkers' Conservation Measure. The Jiralhanae were one of many sentient species indexed by the Librarian for preservation aboard Installation 00. After the Halo Array was fired, the Jiralhanae were returned to Doisac to begin rebuilding their culture.
Doisac is a very war-torn land due to constant Jiralhanae civil warfare, typically between clans. Despite their savagery, Jiralhanae proved intelligent enough to achieve spaceflight and space-faring status. However, their warlike nature inevitably led them into conflict, and eventually the various Jiralhanae master-packs fell into a massive war known as the First Immolation. The planet became heavily damaged from the use of nuclear weapons and almost led to the extinction of the Jiralhanae. The First Immolation didn't stop conflict though as the Battle of Gbraakon took place on Doisac at some point after that. With Jiralhanae society collapsed, by the time the Covenant discovered them in 2492, the species had just rediscovered radio and rocketry. In their primitive state, they were quickly defeated and absorbed into the Covenant.
Time of the Covenant
Great Schism and onwards
During the months of the Great Schism, Doisac was presumed to be a spot for battles between the Covenant and the Sangheili. Although most Jiralhanae returned to Doisac after the war, many also continued to inhabit the worlds the Covenant had previously given them; however, due to their lack of advanced technology and their disorganized society, they were unable to obtain resources or even food for themselves, and instead resorted to raids on Sangheili colonies. The Vheiloth Jiralhanae saw the raids as a necessity, while the Rh'tol Jiralhanae glorified their piracy as power over the Sangheili for oppressing them.
The Jiralhanae on Doisac lacked a strong leader to stabilize them since the Covenant's fall, with the various infighting master packs putting them at a disadvantage in their ongoing conflicts against the Sangheili. One of the governing master packs, Lydus' clan, was willing to attempt peace negotiations with the Swords of Sanghelios on Ealen IV until they were interrupted by a mercenary attack.
By 2558, Atriox had become a symbol to some Jiralhanae on Doisac, with many rallying behind him by enlisting in the Banished. Despite this, many Jiralhanae rejected joining due to their hatred of the Sangheili in the mercenary organization. Working alongside Sangheili was frowned upon on the Jiralhanae homeworld.
Doisac is a tropical world, where volcanic activity is common. At least half of Doisac's surface is covered in rain forests, while the other half is largely composed of molten rock, lava, and large volcanoes. Doisac has a very harsh environment, yet it is still preferred by many Jiralhanae. The rocky, forested planet also contains large amounts of deserts, and a few seas of water.
Its environment is very Earth-like, with forests and oceans, although its gravity is twice that of Earth. It has been noted, however, that its terrain is dominated by magma and magnetism, hinting at high tectonic activity and rich magnetized iron deposits. It is possible that Doisac is closer to Oth Sonin than Earth is to Sol because its surface temperature/climate is slightly more tropical, ranging from -15°C to 52°C (5°F to 125.6°F). Alternatively, its atmosphere may cause a greenhouse effect, either due to the actions of the Jiralhanae or naturally, trapping heat and warming up the planet in a similar fashion to Venus.
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