What was the main reason behind the civil war

The Civil War was based on a disagreement on slavery, but slavery was not the main issue. The Union opposed the South's economic system (slavery) and the South was not too happy about that so they began seceding from the Union. President Lincoln's main goal was to preserve the Union and to get the Southern states to come back. Slavery was just something that had gotten taken care of during the Civil War.

It was mainly about slavery and civil rights. The north wanted freedom, and the south wanted slavery.