Answer:
Southern secession because Southern states said they would secede from the Union if Fremont became president.
Step-by-step explanation:
James Buchanan was the 15th president of the United States. He served from 1857 to 1861, before the Civil War. Prior to this, Buchanan had served in the House of Representatives, as Minister to Russia and as Secretary of State. Buchanan was elected to a large extent because people were afraid of Southern secession, and Buchanan was sympathetic to the interests of the South. He supported the Dred Scott decision and wanted Kansas to be a slave state.