The American Civil War was a conflict fought in the United States from 1861 to 1865. It primarily arose from tensions between the Northern states, known as the Union, and the Southern states, known as the Confederacy. Key issues included slavery, states' rights, and economic differences. The war resulted in significant loss of life and widespread destruction. It ended with the defeat of the Confederacy and led to the abolition of slavery through the 13th Amendment. The conflict had lasting effects on American society and politics, shaping the nation's future.