Lincoln was a member of the Republican Party, which was opposed to the expansion of slavery into new territories. His election signaled a shift in power away from the slaveholding states of the South, which feared that their interests would no longer be protected by the federal government.
In the aftermath of Lincoln's victory, seven Southern states seceded from the Union and formed the Confederate States of America. The Confederacy's leaders argued that states had the right to secede from the United States if they felt that their rights were being violated.
The Union did not recognize the legitimacy of the Confederacy and moved to suppress the rebellion. The Civil War that ensued lasted for four years and resulted in the defeat of the Confederacy and the emancipation of the slaves.