Ping
Many things too many to count brought on the Civil War. Besides slavery there was turf wars over what company or company owner controlled what, tariffs, states rights for powers specifically given to the federal government which were wisely delegated by the founders to go to the individual states. As such many who fought were from non slave areas where slavery wasn't as such profitable such as Mountain Rebels. My late wife's GG Uncle was a Confederate General under Braxton Bragg and was a Mountain Rebel. He was a graduate of West Point as well and had served the Union in previous war.
General Burnside established the National Cemetery in our town. In it lies a Confederate Captain. He is amongst the white soldiers. In another section is the USCT soldiers.
But the worst attack the north did to harm this nation was carried out in NYC in the 1930's. Adolph Hitler expelled a group of Germans he considered a threat. They weren't Jews they were Marxist. A certain NYC university welcomed them here and allowed them to teach. Thus Cultural Marxism as we now see today is destroying what Lincoln could not. Cultural Marxism's more common name is called Political Correctness. The college campus protest and riots originated from it.
Our nation has way too strong a central government. In the past 25 years much more so in abuses. Lincoln, FDR, LBJ, GW Bush, and Obama, have done the greatest damage by expanded federal and executive powers and federal government going way beyond founding fathers intents and the limitations they placed in The Constitution. Nixon to a lesser extent can be added.
Lincoln declared a war upon the southerners who left the Union. The others mentioned declared war upon The Family and in the case of a couple of POTUS the churches as well.