The war fought over issues of state rights and slavery in the United States is known as the American Civil War, which lasted from 1861 to 1865. It primarily arose from disagreements over the balance of power between state and federal authorities, along with the contentious issue of slavery, particularly its expansion into newly acquired territories. Southern states sought to assert their rights to maintain slavery and secession, leading to a conflict with Northern states advocating for abolition and preservation of the Union. The war culminated in the defeat of the Confederacy and significant changes in American society, including the abolition of slavery.