To me Northern and Southern heroes all were great men. I am not against the North, but certainly not against the South. So in my opinion, if the South does not want them,  R. E. Lee statues ought to be placed in Washington DC, preferably next to the Lincoln and the Washington Monument. Both sides were fighting for the preservation of the Constitution as they understood it.

You can ask from a Torah point of view if the war was justified at all? A possible argument could be made from Herodotus and Thucydides about the need to preserve the State.  Cyrus and Darius could walk over just about anyone they wanted to because of the sheer vastness of their state. The Magi or anyone else simply and to give up and join in. The alternative was annihilation.The only thing that could and did stand in the way of the Persian empire was the combined power  of Hellenas, Athens and 300 Spartans. Since  שלום המדינה peace n prosperity of the State is one of the major goals of Torah as the Rambam makes abundantly clear in the Guide, the preservation of the Union does become a valid Torah Principle.