Answer:
The looming issue of slavery under President Lincoln
Step-by-step explanation:
The Southern Dems. who were largely slave owners fear'd that the Republican candidate Lincoln would take away there slaves, forcing them to hire labor for there plantations. The Raid on Harper's Ferry also increased Southern paranoia that more militia attacks like that could occur in the future, damaging there income. Due to the South's paranoia, the Battle of Fort Sumter took place, starting the Civil War!