People are going to dislike you if you make a decision, even if it turns out to be the right one. - James M. McPherson

The great crisis facing the country was the rebellion and anybody in the North who wanted to preserve the Union now found the principal enemy to be those Southern slave owners who had broken up the country. The institution which sustained them and the institution they went to war to defend was slavery. And more and more northerners became convinced of that. As a consequence, a lot of them went the whole way over, from being conservative, pro-Southern, pro-slavery Democrats to becoming radical Republicans. Benjamin Butler is a good example, and Edwin M. Stanton is another one.

To a good many southerners the events of 1861–1865 have been known as 'The War of Northern Aggression'. Never mind that the South took the initiative by seceding in defiance of an election of a president by a constitutional majority. Never mind that the Confederacy started the war by firing on the American flag. These were seen as preemptive acts of defense against northern aggression.

The unending quest of historians for understanding the past — that is, 'revisionism' — is what makes history vital and meaningful.