Members of the same country (the Confederacy wasn't recognized - it doesn't count as a separate country) were making absolute war on one another. It was brother fighting brother.
Answer:
Gulag
Explanation:
The Gulag was a system of forced labor camps established during Joseph Stalin's long reign as dictator of the Soviet Union. The word “Gulag” is an acronym for Glavnoe Upravlenie Lagerei, or Main Camp Administration
