After the Battle of Yavin, the Galactic Empire's Imperial Military Department of Advanced Weapons Research branch maintained a research facility on Dandoran as part of Project Blackwing, a project that was overseen by Sith scientists and saw the use of alchemy and science to achieve immortality. The project culminated in the virus known as "the Sickness", and instead attacked and killed its hosts, turning their bodies into cannibalistic zombies known as Undead Troopers. The zombies had the ability to coordinate their actions and had the ability to pilot vehicles and use blasters. The Imperial garrison on Dandoran was eventually overwhelmed and could not contain the virus, resulting in the infection of Dandoran and Tatooine, forcing the Alliance to Restore the Republic to begin containment efforts.