There were idealists who didn't mind the idea of dying for the country and for freedom, and they weren't necessarily "radical abolitionists." Not everyone was an idealist of course, and after the war, many of the idealists turned cynical as they grew older.
That's exactly what I'm saying: they were fighting to preserve the union, not for abolition of slavery. That's why the Emancipation Proclamation just muddied the political waters.