Since you apparently missed it the first time...
Luke, what exactly made it a noble and heroic act for the American colonies to secede from the British crown over a 4% tax rate, while it was wrong for the Southern states to secede over a 35% tariff that was impoverishing them?
It was essentially the same political act. The only difference was the governments involved in the conflicts. And don't tell me the difference was slavery, either - slavery was not even brought up as a causus belli except by one of the seceding states, and it was not even made an issue by the north until 4 years after the war had started.
A colony of a nation is not the same thing as a nation itself. Although the 13 Colonies were under the rule of Britain, they were not part of Britain in the same way that England, Scotland, and Wales are part of Britain. On the other hand, South Carolina, Georgia, Mississippi, etc., are part of America in a way that the Northern Mariana Islands, Wake Island, Puerto Rico, Guam, etc., are simply not.
Now in the charters for the 13 original colonies, the people who were setting up the colonies did promise loyalty to Great Britain, but it was loyalty as a colony of Great Britain, not loyalty as in becoming one of the Kingdoms of the United Kingdom of Great Britain (Kingdom of England, Kingdom of Scotland, Kingdom of Wales). So because they became colonies rather than Kingdoms, they still had the right to secede later on.
The same thing applies for today's US overseas territories that are not States. Because they are not States, they are not a permanent part of the nation, and thus reserve the right to secede later on, as both Palau and the Philippines have done. But if and when they ratify the Constitution and are approved by the Congress, they will become States, and thus gain all the rights that go along with being States, but will no longer be able to secede.
Now what the confederates tried to do is they tried to take
States and break them off of the Union through secession anyway. That is not legal secession. That is treason.