Which single event between 1846-1860 is believed to have caused the most friction between the South and North with the ultimate result being the South's secession?
The tumultuous time leading up to the South’s secession contains a number of significant events surrounding the larger issue of slavery and its expansion. Nevertheless, the direct catalyst of the South’s final decision to leave the Union was the election of Abraham Lincoln in 1860.
The planter class in the South desired to continue the institution of slavery. With Lincoln’s election, they felt their power in the U.S. Government was diminished. Southerners feared the government would curtail or outlaw slavery.
In addition to the Republican Party's nomination of Lincoln, their party platform included a number of points the South would not tolerate. Republicans were set against the expansion of slavery. Lincoln made it clear that he did not believe states had a right to secede. He also would not give federal property within Southern states to the states so they could control themselves.
The Southern states believed they had no place anymore in the United States’ democratic process. The only way they thought they could preserve their "peculiar institution" was to secede and form their own country.