Essay: ar The American Civil War was a military conflict between the United States of America (the Union), and 11 secessionist Southern states, organized as the Confederate States of America (the Confederacy). It was the culmination of four decades of intense sectional conflict and it reflected deep-seated economic, social, and political differences between the North and the South. One of the major causes of the Civil War was the seemingly endless political disputes over slavery in the Mexican Cession and Louisiana Purchase territories. It ....