When you open fire on American soldiers (Fort Sumter) , declare yourself an independent nation, and raise an insurrectionist militia, you are just going to have to expect a military response from the United States.
The State of Mississippi's official Declaration of Seccesion clearly says the primary issue they were fighting for was the right to enslave millions of humans.
Getting back to your original claim - you said the Gettysburg Battlefield should not be associated with a broader educational purpose about the values and moral principles underlying the battle.
One of our greatest presidents -Abraham Lincoln - disagreed with you. He made crystal clear in his Gettysburg address that the true meaning of Gettysburg was all about the principles and values the North was fighting for - freedom and preservation of our great Union
Oh, bullshit. But you're the sole authority on the Civil War, so you can have the last word. Just don't come up here to Gettysburg to tear down our monuments, you just might get a taste of lead from one of those guns with "military ballistics." In fact, a number of our loads exceed those "military ballistics."