Hostilities began on April 12, 1861, when Confederate forces attacked a U.S. The Union rejected secession, regarding it as rebellion.
Republicans opposed the expansion of slavery into territories owned by the United States, and their victory in the presidential election of 1860 resulted in seven Southern states declaring their secession from the Union even before Lincoln took office. The Union included all of the free states and the five slave holding border states and was led by Abraham Lincoln and the Republican Party. The American Civil War (1861–1865) was a civil war between the United States of America (the 'Union') and the Southern slave states of the newly formed Confederate States of America under Jefferson Davis.
