The American Civil War was a civil war fought between northern and southern states from 1861 to 1865 over the issue of slavery. Abraham Lincoln and the Republican Party campaigned on limiting the expansion of slavery, leading southern states to secede and attack Fort Sumter in South Carolina in 1861. While Confederate general Robert E. Lee won battles in the east at first, the Union eventually turned the tide and Lee surrendered to Ulysses S. Grant in 1865, effectively ending the war.