So we should have let the south secede?
That’s a question that will probably be debated as long as the U.S. exists as a nation. An older co-worker once told me years ago that an elderly relative had two brothers who fought in the war, one for the South and the other for the North. Supposedly, they eventually got around to arguing the causes of the war at each family gathering. Both had good points and had effective arguments. It doesn’t appear that the laws of the U.S. supported the North’s view to keep the South in the union at the time so they decided to settle it by war. But even though slavery was the war cry, it couldn’t have been the real reason for it, judging by the way both slaves and freedmen were treated by the North. Also, 95% of Confederate soldiers were too financially broken to own slaves and didn’t have any belief that they ever could in the future. Many of them would’t own anyone else even if they could. What is clear is that several years later, Germany raised it’s head in WWI and again in WWII. They might have succeeded without a completely united group of states.
Years ago, I read a pretty basic and logical supposition that pondered proceeding historical event outcomes had the civil war not happened or turned out differently. Certainly WWI and WWII (if it happened at all) would have been different. But it went further in that America would have been more than just two nations as there was still a lot of the "west" that would have been disputed. In fact, as I recall, a "war" either then or later might have been inevitable as two or three nations (Consider Texas) claimed territory in the plains, west and possibly even south (Mexico). It also considered potential foreign influence and alliances a early America had a wealth of resources that would make America a valued trade partner.
It's not often in history, we can contemplate stark differences had things gone differently. But the Civil War is one that, at a high cost, seems to have been an investment that solidified a fledgling nation's eventual rise to the world's greatest nation and sole superpower, if only for a century (yet undetermined). It might be another 100 years before we can close the book on it.