That is of course not what I said; "valid" a complicated question, depending on whether we want to get all land acknowledgement and question whether any of the US should have existed at all, including but not limited to the slave states.

An example of "valid" secession is the split of Czechoslovakia.

"Peaceful" is introducing a what-if about whether and why the Confederacy started the actual armed conflict part of the secession.

I have introduced a line break into the original comment as a demilitarized zone.

(we can also see the sort of "historical sliding window" effect as to legitimacy here. At what point does de facto line on the ground become baked in to legitimacy? Does California have a right to exist? Clearly more so than the occupation of Crimea, but is it just time that makes it so?)

> That you think it’s valid for the South to break away so they could continue to treat black people as property says a lot of things, none of them good.

They didn't actually say that, though I can see how one might read it that way.

  valid cases for secession. In the case of the South though

It's like Al Gore "I took the initiative in creating the Internet" being taken as "I invented" rather than "This was invented, I took the initiative in supporting it when that happened".