Why did the South kill so many innocent Union Soldiers in the Civil War (Gettysburg)?

I agree with you that a visit to Gettysberg is overwhelming and every American should visit it. Up until that time virtually all the battles were on southern soil and they might ask you the same question, especially in regard to Sherman's trek to the sea. The victors write the history books. If you take the time to study the southern perspective, you will find the same courage, commitment, and integrity shown by the north. The institution of slavery was a vile practice that had to stop, but you cannot deny the southern soldier his valor anymore than you could defame his northen adversary for the evils of child labor. It is a very sad time in our history and for every Andersonville there is a Camp Douglas. They were ALL Americans and we should mourn them all.