The war fought between the North and South in the United States is known as the American Civil War, which lasted from 1861 to 1865. The primary issue at hand was slavery and state rights, leading to a conflict between the Northern states (Union) and the Southern states (Confederacy). The war resulted in significant changes in the nation, including the abolition of slavery and the preservation of the Union. It was marked by many pivotal battles and profound social upheaval, and its legacy continues to influence American society and politics today.