From Wikipedia
The Civil War
Episode One

The Cause

The American Civil War
1861 – 1865
Also known as the War Between the States
and several other names, was a civil war in the United States of America. Eleven Southern slave states declared their secession from the U.S. and formed the Confederate States of America (the Confederacy). Led by Jefferson Davis, they fought against the U.S. federal government (the Union), which was supported by all the free states and the five border slave states in the north.

In the presidential election of 1860, the Republican Party, led by Abraham Lincoln, had campaigned against the expansion of slavery beyond the states in which it already existed. The Republican victory in that election resulted in seven Southern states declaring their secession from the Union even before Lincoln took office on March 4, 1861. Both the outgoing and incoming U.S. administrations rejected secession, considering it rebellion.

American Civil War
Top left: Rosecrans at Stones River, Tennessee; top right: Confederate prisoners at Gettysburg; bottom: Battle of Fort Hindman, Arkansas
Date April 12, 1861 – April 9, 1865 (last battle ended May 13, 1865) Location Principally in the Southern United States Result Union victory; Reconstruction; slavery abolished; States' rights to secede curtailed
Belligerents
United States of America (Union)	Confederate States of America (Confederacy)
Commanders
Union Leaders	Confederate Leaders
Strength
2,100,000	1,064,000
Casualties and losses
110,000 killed in action 360,000 total dead 275,200 wounded	93,000 killed in action 260,000 total dead 137,000+ wounded

PBS: The Civil War