According to the report, most deaths during civil war are due to:

Most deaths in the Civil War were due to diseases that had nothing to do with combat.
Hope this helps! Please let me know if I'm wrong. :)

Are you Australian? In that case it would rather ironically be the Aboriginals and their children. If not, (and I'm not 100 percent sure about this one) but this was during the time period of the African American rights Reform period in the United States.