History: American Civil War (1861-1865)

The American Civil War (1861–1865), also known as the War Between the States (among other names), was a civil war in the United States of America. Eleven Southern slave states declared their secession from the United States and formed the Confederate States of America, also known as "the Confederacy." Led by Jefferson Davis, the Confederacy fought against the United States (the Union), which was supported by all the free states (where slavery had been abolished) and by five slave states that became known as the border states.
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. In response to the Republican victory in that election, seven states declared their secession from the Union before Lincoln took office on March 4, 1861. Both the outgoing administration of President James Buchanan and Lincoln's incoming administration rejected the legality of secession, considering it rebellion. Several other slave states rejected calls for secession at this point.
Hostilities began on April 12, 1861, when Confederate forces attacked a U.S. military installation at Fort Sumter in South Carolina. Lincoln responded by calling for a volunteer army from each state to recapture federal property. This led to declarations of secession by four more slave states. Both sides raised armies as the Union assumed control of the border states early in the war and established a naval blockade. In September 1862, Lincoln's Emancipation Proclamation made ending slavery in the South a war goal, and dissuaded the British from intervening.