I don’t know of anyone at FreeRepublic (except for the lost causers) who argue that the north went to war to free the slaves. You simply see what you want to see - and fight the strawman you want to fight.
If the Union apologetics argument is not based on the abolition of slavery, then what is the word "Slave" doing in the discussion?
The Southern side argues "Invasion." "Defense of Homeland." "Independence". The Union Apologist side keeps using the "Slave" word.