I'm only getting he usual reaction from the disciples of popular history. It rubs some people wrong - popular history initiated by the leaders of the federal government back in the day rewrote in real time and afterward the history of the war and slavery and other things involving the times. The way they have it is the war was fought by the US to 1) free the slaves; and 2) preserve the Union. Both of these patriotic and moralistic reasons can be proven false even though it is the US as the star of the show.
Different people will give different arguments 1 or 2. Most elite thinkers/writers don't argue the emancipation one any more. That's not to say they are outspoken against it. But interestingly it is what school children are taught not directly but suggestively. Open up any 6th grader history book and you'll see the tug-o-war immediately drawn out in slave vs non-slave sides squaring off on the battlefield.
The worse argument to engage is that of preserving to Union because it seems to make sense. It's not until people are forced to do actual study that they understand the real reason for the war - money and power. But you can't make somebody study. Everybody thinks they know what it's all about, as someone here once said on the causes of the American civil war, "it's ABC". It certainly seems so when the official history has you thinking you got it. Understand the difficulty in arguing against these two. On the one hand you seem to argue a pro-slavery argument fueled by possible closet racism. And on the other you're anti-American, a traitor. These are very emotional things, slavery and patriotism. It encourages people to believe they are knowledgeable.