What event led to the secession of Southern states from the Union?

The election of Abraham Lincoln in 1860 was a pivotal event that directly led to the secession of Southern states from the Union. Lincoln was a member of the Republican Party, which opposed the expansion of slavery into the territories. His election signified a shift in the political landscape, which alarmed many Southern leaders who felt that the future of slavery was at stake. The Southern states believed that they were losing their political power and that Lincoln's presidency would lead to the restriction of their rights, particularly regarding slavery.

In light of this perceived threat, several Southern states chose to secede from the Union shortly after Lincoln's election, believing that they had the right to withdraw from a government that no longer represented their interests. This act of secession set off a chain of events that ultimately led to the outbreak of the Civil War. The other options, while significant in their own contexts, did not directly trigger the widespread secession of Southern states in the same manner that Lincoln's election did.