You grasp the concept, you just can't grasp the fact that the Big City Liberals who believe in tax and spending and using the government for social policy, were the bad guys in 1860.
And that modern big city liberals who control Washington DC today, are descended from the exact same big city Liberals that backed Lincoln in 1860.
In 1860 they were Democrats, allied to Southern slavers to rule over Washington, DC, since the election of 1800.
Thrown out of power in 1860 by rural Republican voters, Southern Democrats declared secession & war against the United States.
Their Northern Big-City Democrat allies either supported the slavers or opposed them only half-heartedly, i.e., George McClellan.
After the Civil War, Democrats North & South quickly reunited and have been waging some form of warfare against the United States ever since.
Why is that so hard for you to grasp?