Rev. Moon was teaching his vision of the unfolding of the providence of the Second Coming of Jesus and the Kingdom of God. His work was very successful, and brought him to the attention of authorities who wanted him removed from the scene so that society could be more quickly controlled totally by a culture of communism. Ironically, it was faith leaders who complained to authorities that led to his trial and imprisonment.
The prisoners had extreme working conditions, very little food, and were not expected to live more than 6 months. The communist regime simple wanted them out of the way but did not want to turn public opinion against their regime by killing them outright. So the death camp was a solution preferred. It served to get rid of those branded as enemies of the state but squeezing all the work possible out of them before they died of exhaustion and hunger.
The fertilizer plant in Hungnam where Moon was a prison laborer from 1948 to 1950 is seen in the two photographs, taken in the 1930s when the factory was run by a Japanese company, the Nippon Nitrogen Fertilzer Co., Tokyo.See Also
Michael Breen's account of Re. Moon's years in N Korean prison