Why did South Carolina secede from the United States?

Even before the Civil South Carolina was a staunch supporter of slavery as well a vocal advocate of secession. They swore that if a republican got elected as president. Like many states who advocated slavery, they were determined to maintain the system no matter what the costs. When Abraham Lincoln was elected president November 9, 1860, their worst fears were realized for republicans were against slavery. South Carolina then seceded from the Union on December 20, 1860. Later Southern cadets from the Citadel fired the first shots at Fort Sumter that triggered the American Civil War.