I think that your point regarding the relatively good behavior of soldiers on both sides of the Civil War is certainly a valid one. However, the fact that the war was conducted in a generally honorable fashion does not mitigate the moral responsibility of those who did commit dishonorable actions. Any number of civilians intentionally killed constitutes a war crime.
Is it a valid defense for a murderer in a criminal trial to point out that the society in which he lives has the lowest murder rate in the world? Obviously not. You seem to be using a similar defense for those men who committed war crimes during the Civil War.
You assume that the question has been fully adjudicated, and firmly established that some forces in our Civil War did commit "war crimes".
The truth of the matter is that, by their own standards and even by ours today, very few Civil War units committed "war crimes".
I listed some candidates for "war crimes" in my post #169 above, but the only one on that list actually charged & hanged, again, was Champ Ferguson: for the murder of 53 civilians.
Ferguson is the exception which proves the rule: very few Civil War "war crimes".
Of course, if you wish to redefine the term "war crime" to satisfy our most pristine moral code, then you could possibly define the entire conflict as a "war crime", and hang every one of them -- Union, Confederate, military, civilians: anybody who supported the bloody war, hang them all for your pristine definition of "war crimes", right?
Oh? You don't like that idea? Seems a bit extreme, does it?
Then why would you even consider imposing today's standards on ancestors who obviously knew in their own minds, what was a "war crime" and what wasn't?