Even at college (a community college) I had a history teacher trying to distort and confuse the Civil War to not be about slavery.
But definitely school history has agendas that don't put teaching facts first. Such as it tends to glorify empires while dismissing everybody else as uncivilized barbarians who were warring against the Empire.
To be sure, it's a complicated war with a complicated history, along with many other aspects of U.S. history, including slavery and westward expansion, which were both part of the same general equation. As a result, the memorialization of it and the historiography has also had a complicated history. I had a history teacher who was from a former Confederate state who taught more of a "lost cause" version of history, though not the complete snow job one might hear from the more fanatical pro-Confederate types. I think he tried to gloss over "the cause" as much as focus on examining the military history - the campaigns and battles.
I also remember a history pageant we did in sixth grade (when I was in NY), and part of it involved a couple of kids, one dressed in a blue Union uniform and the other in gray, reciting a touching poem about a soldier who fell at Cemetery Hill. That was also a big part of the Civil War history package - the sadness and tragedy of "brother against brother." It wasn't that anyone was denying slavery as the primary cause, but it was more a feeling where the cause was secondary because the war itself was so horrible and sad, but once it ended, we made up and we were one big happy family again. That seemed to the primary objective in handling Civil War history.
Of course, President Abraham Lincoln (whose birthday is in six days, in case anyone still celebrates it) has gone down in history as the one who freed the slaves and preserved the Union, viewed by many as truly the greatest President in U.S. history. His temple in Washington DC is one of the most prominent and stately - a symbol of America itself. Archeologists in the future may uncover it someday and believe that Lincoln was worshiped as a god - and there may be some truth to that. Was Lincoln really that great? And if he wasn't that great, why did we make him great? Why did America need to have a great martyr to die for our sins? Were our sins forgiven?
I think Lincoln acted in the best interests of the United States, as they were at that time, and I believe that his Abolitionist beliefs were truly sincere. The Election of 1860 was a bit of a debacle, though Lincoln's election proved that it was time for America to change. Slavery had to end, it was already ending everywhere else and rapidly becoming an anachronism. Compromising was over, and it was time for an all-or-nothing gambit to settle the question of slavery once and for all. However, I don't believe the North's motives were entirely compassionate or humanitarian. Most still believed in the basic concepts of white supremacy, yet still opposed slavery for other reasons. Economically, southern cotton was no longer "king," as northern industries started to dominate the national economy. England was seeking out other sources of cotton, so they didn't need it anymore. Also, they were importing food from the Union states, which they needed more than Confederate cotton, which they could get from other places (Egypt, I think).
I think the key problem with approaching the history of slavery and the Civil War, it's not that people keep saying that the war was not about slavery (which I agree is a gross distortion of historical fact), but it's that there have been generally poor excuses and explanations for what took place in the Postbellum period. It's often what's told in the results and aftermath which gives away the underlying causes of the war. Slavery did end, which is a historical fact, though we also know that life didn't really get that much better for anyone who wasn't white in America during that time. But on paper, the 14th Amendment ensured that everyone would be a free and equal citizen of the United States - even those confused indigenous people in the western territories who somehow thought they were living in their own country. They became citizens, too, whether they wanted to be or not. "Separate But Equal" was probably one of the biggest piles of BS lawyers ever came up with, but that remained the law of the land until 1954, almost 90 years after the end of the Civil War and the end of slavery.
That's why I might sometimes get impatient when people argue about the Civil War, and by extension, arguments over the Confederate flag and all those statues that they were tearing down a few years ago. Even though I agree with the reasons for tearing them down and that they should be torn down, some of it seemed a bit misplaced and misdirected. Do we really need to argue about the Confederate States of America or what reasons they might have had for existing? They lost the war. The United States of America won the war. We don't need to ask why the Confederate States wanted slavery or racism, since that part is obvious.
The greater historical issue to resolve is why the
United States chose to maintain Separate But Equal and a generally white supremacist set of policies and institutions, which largely continued unabated after the Civil War and didn't face any significant legal challenges until after World War II.
I think we're at the point now where America is in a position not unlike that of Michael Douglas' character in
Falling Down where he asks "I'm the bad guy?" After a trail of murder and mayhem, he suddenly reflects and wonders "Wait, did I do something wrong?"