The major military conflict fought between the North and South in the United States is known as the Civil War, which lasted from 1861 to 1865. Central to this conflict were issues such as states' rights and the contentious issue of slavery. The Northern states (Union) fought to preserve the nation and ultimately abolish slavery, while the Southern states (Confederacy) sought to maintain their independence and the institution of slavery. The war resulted in significant casualties and destruction, leading to profound social, economic, and political changes in the United States, including the passage of the 13th Amendment which abolished slavery.