Under that same reasoning, if the progressive income tax was such a bone of contention then why was one of the first major acts of Ronald Reagan's presidency the passing of a tax bill?
In case you are still lost as to the answer (which would not surprise me in the least considering your economic ignorance and willful dishonesty), both bills had something in common - they enacted lower tax rates than the liberals had. With the civil war, the north installed a rate of about 36% that rose to over 45% by the war's end. The confederates enacted a rate that was half of that at about 18% and lowered it even further to about 13% by May 1861.