American Civil War The American Civil War (1861–1865) was a major war between the United States (the "Union") and eleven Southern states which declared that they had a right to secession and formed the Confederate States of America, led by President Jefferson Davis. The Union, led by President Abraham Lincoln and the Republican Party, which had opposed the expansion of slavery into territories owned by the United States, rejected any right of secession. Fighting commenced on April 12, 1861, when Confederate forces attacked a United States (federal) military installation at Fort Sumter in South Carolina, the first state to secede. |