A Nation Divided. A Nation Reborn

The American Civil War lasted from April 1861 to April 1865, and remains the deadliest conflict in the country's history— an estimated 620,000 to 750,000 American deaths, more than in any war before or since. It grew out of decades of unresolved tension between North and South over slavery, states' rights, and the balance of political power between free and slave states, tension that finally broke the Union apart after Abraham Lincoln won the presidency in 1860 and eleven Southern states seceded to form the Confederate States of America. At its core, the war was about slavery. The Confederate states said so plainly in their own declarations of secession, citing the protection of slavery as their primary reason for leaving the Union.