Concentration camp
During the American Civil War in the 1860s, soldiers who had been captured were sometimes put in camps.  These camps were meant to be prisoner of war (POW) camps, with good conditions.  However, as the war went on, both the Union and the Confederacy captured more enemy soldiers.  The camps became very crowded, with terrible conditions.  There was not enough food, and many men died from hunger.  Also, there was also very little sanitation, which made it easy for diseases to spread.  Many prisoners died from these diseases.