You can argue all day about what constituted the actual start. Southerners like to point to Brown because it deflects the blame from themselves. Brown was a homicidal maniac, and though he enjoyed support among many abolitionists he was never in a place to start a slave uprising. Those who supported Brown and his actions were similar to those who support people who kill abortionists or blow up abortion clinics. They come from the fringe.
It should also be noted that Brown was convicted and executed for treason against the Commonwealth of Virginia. Brown was not born in Virgina, had never lived in Virginia, and owed no allegiance to Virginia. How he could commit treason is beyond me.
This is not true.
Brown's supporters after-the-fact included the cream of New England's intellectuals and upper society. Thoreau, Emerson, Bryant -- all supported Brown, Thoreau in particularly bloodthirsty language. Walt Whitman was almost alone in his denunciation of Brown.
The South noticed. And that was the end of the Union.
What followed has been a sectional Empire founded on blood, money, and violence.
Southern States still can't hold an election, 43 years later, without "pre-clearance" from the Civil Rights Division of the Justice Department. How is that anything but abjection and humiliation? It certainly isn't the Union of Washington and Jefferson.