The Angosians were an intelligent humanoid race originating from the planet Angosia III. Outwardly indistinguishable from Humans, Angosians eschewed violence, preferring to focus on intellectual development.
In the mid-24th century, the Angosians were involved in a protracted conflict called the Tarsian War. Being inherently non-violent, the Angosian authorities ordered their soldiers subjected to genetic engineering and chemical manipulation in order to make them superior soldiers and survive. This treatment meant that their behavior radically became violent when they sensed danger to themselves. This treatment was successful and the conflict ended.
However, it was discovered that the process was irreversible, and, when the "super soldiers" returned to normal Angosian society, they were unable to function within or co-exist alongside them. No attempt was made to give them even a partial recovery as the government decided they may need to use them again. After a referendum by the larger population, the soldiers were relocated indefinitely to a penal settlement on Lunar V, and considered to be outcasts and criminals.
In 2366, the Angosians petitioned to join the United Federation of Planets. The USS Enterprise-D visited Angosia III to follow up on the petition. However, the occasion was interrupted by the escape of the soldier Roga Danar who was pursued by the Enterprise crew at Angosia III's request. The crew then captured Danar and learned of the gross systemic sentient rights violation of the training program. Danar escaped again and proceeded to start a rebellion with his fellow soldiers, storming the main government building. In the face of the planet's unacceptable policies and the resultant civil upheaval caused by them, the application was put on hold for the immediate future. (TNG: "The Hunted")