“To a rational man, it demonstrates clearly that slavery was not the issue to which the North objected.”
How many times do I have too spell it out?
THE SOUTH FOUGHT TO PRESERVE SLAVERY!
THE NORTH (AND ABOUT 100,000 SOUTHERNERS) FOUGHT TO PRESEVRE THE UNION!
THE SOUTH FOUGHT TO PRESERVE SLAVERY!
Because it is clearly and demonstrably a lie, you have to repeat it quite often to convince gullible people to believe it. That's why it has been repeated loud and often since 1863. (Notice I didn't say 1861? It's because they weren't even trying to push that crap in 1861. They started pushing it in January of 1863.)
It is clearly contradicted by the evidence of the "Corwin Amendment", but you still desperately want to believe the war was somehow about slavery, instead of about the 238 Million dollars of European trade that would move from New York to Southern ports, and thereafter threaten these same New York industries by supplying the interior of the nation with Imported European goods, instead of theirs.
Besides that, it doesn't really matter why the South was fighting off an invasion, it only matters why the North was engaging in Invasion.
Invaded people get more leeway on why they were killing invaders, it is the invaders that have to justify why they were invading someone else.