The conflict fought between the North and South in the United States was the Civil War, which lasted from 1861 to 1865. The war was primarily about the preservation of the Union and issues related to slavery, states' rights, and economic differences. The Northern states (the Union) fought against the Southern states (the Confederacy) that seceded from the Union. The war resulted in significant loss of life, social upheaval, and ultimately led to the abolition of slavery with the passage of the 13th Amendment to the Constitution.