Prisoners of war normally were beaten and most died from the mistreat of dehydration, starvation, illnesses, and torture. Others were killed on the spot by the enemy. These soldiers who died as a prisoner, where usually never found, and so they were accounted as unaccounted. They were never found so their deaths were noted as unaccounted.
World War 1: 320,000 Americans Dead
3,300 Americans Unaccounted for
World War 2: 16 million Americans Served
400,000 Americans Dead
79,000 American Unaccounted for
Korean War: 54,000 Americans Dead
7,500 American Unaccounted for
Vietnam War: 211,000 Americans Dead
1,600 Americans Unaccounted for