Any understanding of this nation has to be based, and I mean really based, on an understanding of the Civil War. I believe that firmly. It defined us. The Revolution did what it did. Our involvement in European wars, beginning with the First World War, did what it did. But the Civil War defined us as what we are and it opened us to being what we became, good and bad things. And it is very necessary, if you are going to understand the American character in the twentieth century, to learn about this enormous catastrophe of the mid-nineteenth century. It was the crossroads of our being, and it was a hell of a crossroads.
An excellent brief retelling of the Civil War by the Civil War Trust using animated maps: