Why it started:
The main catalyst for the Civil War was the long-standing conflict between the Northern and Southern states over the issue of slavery and states' rights. The election of Abraham Lincoln, who opposed the expansion of slavery, as president in 1860 and the South's refusal to accept its outcome resulted in the secession of 11 Southern states and the formation of the Confederate States of America. Union troops fired on Confederate forces at Fort Sumter in South Carolina, starting the war.