Excuse me, but you seem to be having difficulty of understanding the word "Might" in context. The Union population was double the Southern Population, Their industrial base was many multiple times bigger, their land mass was bigger still.
All the "Might" was on their side, and they used it to invade and conquor people who were defending their homeland.
The CSA didn't invade the Union, nor did it pose any serious threat to it. The provocation which you still whine about is damage to a bunch of rocks, and loss of pride at having been kicked off of other people's land.
Certainly not worth killing 600,000 people for, at least not to a sane man.