Well if you want to talk about our current government, who initiated undo force on the CSA, 600,000 died on either side.
They could have just not invaded us, but done some pretty harsh economic things to us, to force us back into the Union and eventually, slavery would have ended as it was replaced by the Industrial Revolution, and I would have hoped that reason and true freedom and liberty would have prevailed as well in the minds of the White Oppressors. It would have surely taken a lot longer, but you get my point.
So there you go, our current government, the United States of America initiated an invasion that killed 600,000 people. There is your "tens of thousands" right there. Easy enough. LOL Of course I'm only half kidding.