They couldn't convict OJ of murder either. I suppose you think he's innocent as well.
I think that if they had attempted hanging Confederate soldiers for Treason, it would have backfired very badly in their own states.
I'm not asking why they didn't hang Confederate POWs. I'm asking it, given Southern standards, if the Union would have been justified in hanging them? Especially those who had been members of the U.S. Army before the rebellion began?
The Soldiers which you clearly did not mention were traitors, were in fact as demonstrably traitorous as it is possible to be.
As traitorous as the rebel soldiers were.
Here in the United States we have alliances with all sorts of foreign nations. Their Troops come here to train. If we go to war with one of their countries, the fact that they trained in our Army, or even if some of them joined our Army and left, would not make of them traitors because they never owed a primary loyalty to it anyway.
The Nation was founded as a confederation of States, and up until the 1860s, the primary loyalty of most men were to their own state. This was simply accepted and understood, and the fact that they may have previously served in the Federal Coalition did not excuse their expected loyalty to their own state.
But that was back before the Federal government became so powerful and all encompassing.
Needless to say, the North didn't even try that approach.
And that's really all the time I intend to spend on this particular stupid and pointless conjecture.