The Southern side argues "Invasion." "Defense of Homeland." "Independence".
Jeebus but you're obdurate. Only the lost causers cited those and only after the fact. The confederates said one thing (besides their temper tantrum "nobody gonna tell me what to do!") and that was SLAVERY.
If you had been born in Germany, i'm sure you'd be a good little Nazi as well. Your argument that MIGHT MAKES RIGHT is the excuse all totalitarians have used throughout history.
Yes, you're proud, because your father brainwashed you into being proud of one of the least proud moments in this nation's history. The pity is that you are susceptible to such conditioning instead of being objective and rational.
The Union forces didn't fight to end slavery. They (mostly) didn't care about ending slavery until their superiors told them that they would care about ending slavery, at which time they stood ready to enforce those new commands too.
It might as well have been the Sudetenland, of which i'm sure the Germans were also proud.