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, regarding it as rebellion.
Confederate Vice President Alexander Stephens said that slavery was the chief cause of secession in his Cornerstone Speech shortly before the war. After Confederate defeat, Stephens became one of the most ardent defenders of the Lost Cause.
There was a striking contrast between Stephens' post-war states' rights assertion that slavery did not cause secession and his pre-war Cornerstone Speech. Confederate President Jefferson Davis also switched from saying the war was caused by slavery to saying that states' rights was the cause.
While Southerners often used states' rights arguments to defend slavery, sometimes roles were reversed, as when Southerners demanded national laws to defend their interests with the Gag Rule and the Fugitive Slave Law of 1850. On these issues, it was Northerners who wanted to defend the rights of their states.