The Civil War was mostly about the disagreement of abolishing slavery between the Union states (northern states), and the Confederate states (southern states). At the beginning of the war the Union states had a total population of 22 million people. The Southern states had a total population of about 9 million. The war tragedy was reflected in the size of the armies in the field. The northern forces outnumbered the southern forces.
On April 10, 1861, South Carolina, Confederate forces demanded Fort Sumter’s surrender. The fort’s commander, Major Robert Anderson, refused. On April 12, the Confederates opened fire with cannon. At 2:30 p.m. the following day, Major Robert Anderson surrendered. Then the war began.