Why did southern states secede from the union?
Lincoln’s great claim to fame was when he freed the slaves of the south. Slaves in any state that did not break from the union were still slaves. This freed virtually zero slaves as the south did not recognize Lincoln’s authority over them. The war became a moral issue now. Slavery, most would agree, was terrible. Freeing the slaves of the south became good press. (We ignored the slaves states in the north until after Lincoln’s death). Today, we remember only the politics of this wonderful concept.