If post 1900 is allowed for consideration, then German, Italian and Japanese wars. Could not have backfired any more than they actually did, with proponents vanquished in quite litteral sense of the word.
But Italy, Germany and Japan are all extant countries nowadays, and quite considerable ones indeed. The CSA is not. The ACW ended with the destruction of a) the country as a political entity (although the individual states survived, so, well) b) the system the country was born to preserve in the first place c) the political power of the old elite. Italian defeat in WWII, while considerable, did not end up with the wholesale annexation of the peninsula to another state, or the recreation of pre-unitary duchies. Same thing for Japan. Germany is trickier, since it was divided for a long time after the war... and yes, of course, all the ideals (if you can define grand murder and massive enslavement of people as "ideals") the Nazis had fought for were utterly crushed. (Ok, maybe the reasons behind the Nazi fighting were a bit more complex; but the plan was undeniably to enslave a lot of people).
Austria as well, is still found on the map, though the degree of "backfireness" suffered by the Austrian Empire in 1918 is quite large.
I think some colonial wars may qualify.