Howdy Cheburashka,
Re-read Mr. Longstreet’s fictional sequence of steps.....free the slaves THEN declare independence.
Then for kicks, read the book I suggested....The 11 Nations of North America....and the few others it mentions as well like Albion’s Seed.
The slave masters of the deep south were just one of three “nations” that seceded in 1860/1. Each national culture(the Tidewater Elite, parts of the Appalachians, and the Deep Southern) each seceded for its own reasons. Only the slave masters for slavery.
My mothers family in WV fought for the Reb’s purely because they hated meddling Yankees and still do. My father’s Unionist family in WV hid runaway slaves and smuggled in English manufacture from Canada via their hardware business to beat the tariffs.
The families lived 7 miles apart. There are a million similar stories.
Both sides were right and both were wrong. 600,000 died and we are all still struggling with the results.
Histories, like people, are never simple.
Za Rodinu ee svaboda!
In any case the confederate constitution was specifically crafted to make the abolition of slavery impossible.