Civil War:

(1861-1865) The American Civil War, or the War Between the States happened because for several reasons, including whether or not to emancipate the slaves. It started in 1861 when South Carolina seceded from United States and formed the Confederate States of America. 12 other states joined the confederacy but the Union army led by Ulysses S. Grant in the end won the war. President Abraham Lincoln emancipated the slaves at the end of the war.
http://www.pbs.org/civilwar/