Devil's Punchbowl (Natchez, Mississippi)
The Devil's Punchbowl was a concentration camp created in Natchez, Mississippi during the American Civil War to house freed slaves. Description 
In order to house the large numbers of African Americans, the Union Army created a concentration camp for newly freed enslaved Black persons at a location known as the Devil's Punchbowl, a natural pit surrounded by bluffs. Many of the formerly enslaved there died of starvation, smallpox, and other diseases. It has been suggested by some that over 20,000 formerly enslaved people died here in one year. However, the scale of the tragedy has been disputed by multiple historians, with history professor Jim Wiggins arguing the 20,000 estimate is baseless and inflated tenfold, and author and activist Ser Seshsh Ab Heter-Clifford M. Boxley referring to the story as "concocted Confederate propaganda" aiming to cast the Union Army in a negative light. References

American Civil War prison camps
Buildings and structures in Natchez, Mississippi
American freedmen
Military operations of the American Civil War in Mississippi

Pretty sure it’s not embellished and the Union Army were no saints
https://aaregistry.org/story/the-devils-punchbowl-a-brief-story/