What was the deciding factor that caused the first group of southern states to secede from the Union?

Answer 1

The first states seceded when Abraham Lincoln was elected president. Officially, Abraham Lincoln believed that all new states admitted to the Union should be free states. Although Lincoln was viewed as a moderate in the North, he was considered an extremist in the South. Southerners feared that Lincoln would not allow slavery to continue at all, even though Lincoln did not espouse this as his official position.

South Carolina was the first state to secede, declaring itself independent from the Union.

Answer 2

Republican Abraham Lincoln won the 1860 presidential election. Lincoln was a moderate Republican, who swore to protect and enforce the US Constitution. The US Supreme Court had ruled that slavery was legal in a 1859 decision. Lincoln tried to assure the South that he had no intention to harass slave holding states. Personally he was against slavery, however, he was a "Unionist" meaning that holding the USA together was his primary goal. Lincoln's election would bring in a Republican Administration. And, radical Republicans and abolitionists could be expected to support any measures that were legal to thwart the expansion of slavery.Even with US Supreme Court protection of slavery, Southern slave holders believed their influence and power would be marginalized by a Republican Administration. They believed that only an independent nation, a Confederacy, was their best chance to protect their power, culture and slavery.