Articles ยท Causes of the War
Historians overwhelmingly agree that slavery lay at the root of the sectional conflict. The question of whether the institution would expand into the western territories had inflamed American politics for a generation before the war.
The free-labor economy of the industrializing North and the slave-labor plantation economy of the South had grown into two distinct societies with clashing interests and values, and the political compromises that held them together steadily broke down.
The Kansas-Nebraska Act, the Dred Scott decision, John Brown's raid, and finally the election of Lincoln in 1860 convinced southern leaders that slavery could be protected only outside the Union. Secession followed, and with it the war.
The causes outlined here sit inside a longer story of secession, war and emancipation. That wider narrative is collected on the Civil War overview.