It was not only the cause of the war, it was THE ONLY reason for the formation of the modern Democratic Party, and that is what is even more amusing about neo-Confeds. To attack Lincoln, they have to link arms with the Democratic Socialists. HAHAHAHAH.
Incorrect as any honest historian of the subject would tell you. Fitzhugh was on the margin of his own time. In fact, those who paid the most attention to him were northerners who used his rantings to incite alarmist reactions for their own political gains.
But based on your posts it is obvious that this matters not to you, just as Lincoln's embrace of the labor theory of value matters not to you. You seem more interested in historically shaky, radically pro-northern rants designed to incite reaction and little more.