The fundamental cause of the war was the institution of slavery and the deep division it created between the North and the South.

The Southern economy was agrarian and heavily dependent on enslaved labor to produce crops like cotton.

The Northern economy was more industrialized and based on free labor.

The conflict involved a constitutional dispute over states' rights versus the power of the federal government.

Westward expansion created intense conflict over whether new territories would be admitted to the Union as free or slave states.

A series of political compromises, like the Missouri Compromise and the Compromise of 1850, failed to resolve the underlying issue.

The growing abolitionist movement in the North, which called for the end of slavery, increased tensions.

Key events like the Dred Scott Supreme Court decision and John Brown's raid on Harpers Ferry further inflamed passions.

The election of Abraham Lincoln, of the anti-slavery Republican Party, as president in 1860 was the final trigger.

Following Lincoln's election, eleven Southern states seceded from the Union, leading to the outbreak of war.