The notable military conflict that took place from 1861 to 1865 over states’ rights and slavery was the American Civil War. This conflict arose primarily from tensions between the Northern states, which opposed slavery, and the Southern states, which sought to maintain their slave-based economies. As a result of these opposing views, eleven Southern states seceded from the Union to form the Confederate States of America, leading to a brutal war that resulted in significant loss of life and destruction. The war ultimately led to the preservation of the Union, the abolition of slavery through the 13th Amendment, and profound social and political changes in the United States.