Le sigh.
The Civil War, like most big history, becomes mythologized over time. The Civil War is no different than the Trojan War in this respect, but it is amazing how quickly the mythologizing started. It shouldn't really be that difficult to see though. Look at Vietnam and the Gulf Wars and the War on Terror, and you can see how fast politics and justifications and accusations can grow and spin out of control.
The main revisionist thread that everyone likes to talk about and pound on is the "Lost Cause" revisionism. Lost Cause revisionism is generally the idea that slavery had nothing to do with the Civil War, but it has many other romantic aspects to it, such as the "why" and "how" the south lost, and enters into the morality of those fighting on the side of the south. It's amazing how quickly the "Lost Cause" revisionism started, almost immediately after the war ended. But there are certain aspects of it that are true.
The idea that slavery had nothing to do with the war is ludicrous. I've stated that already. Without slavery, the war would not have occurred. It is a root cause of many of the lesser causes, including states rights, though the ideas of states rights and slavery are separate constitutional issues. Nevertheless, Alabama was not fighting for marijuana legalization or the death penalty.
But the South was largely outnumbered and under equipped. The defeat of the South had to do with material and tactical and strategic concerns rather than moral concerns. I suppose it's possible God fought on the side of the Union, though I figure most liberals today would find this ridiculous. It is one of those things that probably got the good ole boy's dander up.
There was a great deal of bravery, fortitude, and craft exhibited by the Southerners during the war. Even President Grant could admit as such. This fortitude was given respect by those who understood it's meaning and power. Regardless of the cause, enemies found virtue in each other, and gave respect when it was due.
It's true that a great deal of the southern population probably didn't give a damn about slavery. I could believe the vast majority of them were racist, but they still didn't care about slavery and probably would not have fought if it were their sole motivation. I feel a great many of them fought because they felt it was their duty to the government of their state, which they saw as a higher authority than the federal government. Even President Grant fought in the Mexican War, despite feeling it was an immoral war, because of duty.
But in my opinion, the south were not the only ones guilty of revisionism, even immediately after the war. To say that slavery was a cause of the war, or even THE cause of the war, is a different proposition than saying that the war was fought over slavery, or that it started over slavery, or that slavery was the PROXIMAL cause of the war.
The lead up to the Civil War during the 50s was a political one. It's no more different than people counting seats today. The slave states were desperate to maintain a slim majority or at least equality in the US Senate. The writing on the wall had been seen long ago that the House would be primarily northern and free state. The Senate was the last place the slave states could oppose legislation freeing the slaves, which the abolitionists had fought for.
But the Kansas-Nebraska Act had basically upended the Compromise of 1850, and by the election of 1860, it was evident that the slave states had lost the Senate. Their last refuge was the Presidency. The Democratic Party, north and south, did not call for abolition, but the Republican Party had. More specifically, the Republican party platform demanded the end of the growth of slavery into the territories. No more slave states. For the Republicans and abolitionists, it was a moral matter. To the Southerners, it looked like a political move.
The election of 1860 brought the first Republican President, in Abraham Lincoln. The deck was stacked and the political battle was over. Lincoln had not run on abolition, but had run on the end of the growth of slavery in the territories. He had been able to defeat more radical abolitionists elements in the Republican Party at the convention of 1860. Lincoln desired to enact legislation to free the slaves in the south, and to monetarily compensate their owners, but it was not something he was ready to start a war over. Lincoln won the vast majority of the north, but not by huge margins, against the northern democrat, Stephen A Douglas, who had run on a compromise platform that did not emphasize the abolition of slavery. If you cared about slavery, you voted Lincoln. If you did not, or were concerned about southern secession and war, you voted for Douglas.
Similarly, the chief opponent to Breckenridge in the south was Bell, who ran as a Constitutional Unionist, who were against secession. The choice to the southern voters was "for secession" and "against secession, whatever happens to slavery". Even Breckenridge advised against secession and was part of the "border state neutrality" group, which included the swing vote in Virginia. Both Bell and Douglas gave Lincoln and Breckinridge a run for their money in the north and south.
Lincoln won 40% of the popular vote. But he won a vast amount of the electoral votes. The southern voter might as well have stayed home. The election was decided by Lincoln vs Douglas. Lincoln wasn't even on the ballot in most slave states. This doesn't really matter as much to those who look to the Constitution, but even today, the winning of the Presidency without a majority of the popular vote is quite controversial. Cries of "Not My President" today should generally give you an idea of how Southerners saw President Lincoln.
It was after the election of Lincoln that the slave states started calling conventions to secede. The proximal cause of the Civil War was the election of Abraham Lincoln, whom the southerners saw as illegitimate, and whom they hated because he was part of the Republican party which had begun adversarial politics against slavery. This is no stranger to us today who see a growth of demonization in politics, and generally a very emotional backlash against it. Part of the rationalization of the whole MAGA! movement is the idea that liberals and progressives have impugned the morality and character of those who were against same-sex marriage, gun control, illegal immigration, voter ID, etc. The argument being that liberals and progressives were the enemy, plain and simple, because they had attacked the character of conservatives. The same argument was made against the Republicans in 1860. They attacked the character of southerners, hence they were the dastardly enemy. This goes to a psychological cause of war.
Lincoln tried to hold the thing together. In his inaugural address, he expressed support for the Corwin Amendment. Seeing the writing on the war, the House attempted to hold things together by passing an amendment to the Constitution that would have expressly protected slavery inside the slave states. Lincoln seemed perfectly willing to keep slavery in the slave states to preserve the Union.
It seems that slavery inside the slave states then was not threatened. Only the growth of slavery in the territories. But by this time, it didn't matter to the southerners, who had whipped themselves into a fury, getting their dander up. Secessionist Conventions were called in the southern states. The deep south started to secede. The votes in the conventions were quite one sided, with the majority of the delegates voting for secession almost immediately. There are questions as to who exactly got invited. Some argue that non-secessionist southerners didn't even vote for delegates, because they saw the entire process as disloyal. Hence the conventions were stacked with secessionists. One by one, the southern states began to secede.
The exception was Virginia. There were three factions in the Virginia convention, each about 1/3 of the total. First were the secessionists, who wanted Virginia in the Confederacy. Second were the Unionists, who wanted to keep Virginia in the Union, Confederacy or no, slavery or no. Most of these were from West Virginia. The third faction, the swing faction, were those who wanted to stay in the Union, but desired to stay neutral in the fight between Lincoln and the Confederacy. After Fort Sumpter fell in Charleston harbor, Lincoln called up the army and asked for Virginia to contribute. This was too much for those who wanted to stay neutral in the coming war, so the swing faction voted to secede in the second convention. It was the appearance of Lincoln as invader that turned Virginia to secession.
This does not take away slavery as the root cause of the war, but it does mean that the causes of southern secession were complex. I'm personally in favor of Mark Twain's take on the start of the war being too many Sir Walter Scott novels.
Sir Walter had so large a hand in making Southern character, as it existed before the war, that he is in great measure responsible for the war.
Southerners had a distinct view of honor and morality, and it could not countenance attacks on their morality or the morality of their "peculiar institution". Slavery was somewhat taken off the board by the Corwin Amendment. All that remained was political power as assurance and their sense of being attacked by northern Republicans and abolitionists. It's no different than Trumpists saying progressives and liberals are to blame for Trump because they were called racists. It's all insane, illogical, and bereft or reason, but it's nevertheless their psychology.
Slavery cannot stand alone as the reason because there were other options for everyone involved. Lincoln and Congress attempted to put forward some of these options. Secession could have been attempted non-violently and brought before the Supreme Court. But that is not how southern honor demanded it be fought. Hence the great flushing sound of the Union in a deluge of blood due to a great temper tantrum.
President Grant himself writes in his memoirs about slavery being the great cause of the war. I personally believe this is the second form of revisionism that we deal with. I'm unsure if slavery as "the great cause" of the north appeared before or after the "Lost Cause" revisionism, but I know it started rather quickly.
Why do I believe it is a type of revisionism? Grant himself admits to being no abolitionist at the start of the war. I don't think it is deniable that a great many northerners who fought for the Union were not abolitionists, or were in some cases only slightly less racist than their southern counterparts. Lincoln himself sought to preserve the Union by constitutionally protecting slavery in the slave states. So what was the cause, the root of this view of the war in the north?
Nobody thought the war would be as bad as it was, as long as it was, as deadly as it was. Only people like Sherman, who were seen as insane at the start of the war, believed it would be as bad as it was. A total of 215,000 deaths were attributed to combat in the Civil War. 140,000 alone on the north. Were you to line these men up, shoulder to shoulder, along the side of a road, 1 meter per body, the line of dead men would stretch for 155 miles. 87 if were are only counting northern deaths. If you walked along the road to view all the bodies, and walked 25 miles a day, it would take you a week of walking to view all of the bodies. 7 days, nothing but dead men. This does not count all of the deaths attributed to the war by sickness and other causes. That would be roughly 750,000 dead and a line that stretched a bit over 450 miles long. That's the distance between Boston and Washington DC. If you took the blood of all the men killed in combat, at 5L per man, it would fill a pool slightly larger than 61 feet long, 61 feet wide, and 10 feet deep. That doesn't count the blood of the wounded.
If you had said the war would cost that much in 1861, you would have been locked up as a madman. Nobody believed it would have been that bad except a few crackpots. If you could have presented these 140K deaths to the north in 1861, I'm doubtful there would have been a great deal widespread support for the war. As it was, the war was not hugely popular to some in the north. But confronted with such a death toll, support for Lincoln would have probably evaporated in the north, slavery notwithstanding. At the end of the day, a great deal men in New York really didn't care that much how many people a man in Charleston owned. That's not a defense of slavery, it's a simple declaration of the degree of motivation of people to fight against it.
How do you justify these deaths? The mountain of casualties? I hesitate to call it a river of blood, but certainly a stream of it. Lincoln was under pressure from the start. Only impending victory saved him in the election of 1864. For Lincoln, it was the idea that the deaths had not been in vain. It had not been for nothing, and the cause of those deaths, regardless of any personal motivations, was the cause of liberty and freedom and equality for all men. Lincoln himself, so eloquently put in the Gettysburg Address, argued that those deaths had been in the cause of ending slavery. Grant made the same argument.
Regardless of how you view that argument, or how you view the motivations of the majority of northerners, I think you could admit that nothing but ending slavery could have justified such a sacrifice on the people of the United States. Despite the fact that in 1861 a majority of the people in the north, and the government itself, including Lincoln, signaled a willingness to keep slavery in the slave states to preserve the Union, by 1863 ending slavery was the only cause that could justify the war. What was a non-issue in 1861 to the majority, became the great crusade.
I don't see how this could be surprising. We see it today and see it throughout the history of the United States. We hear about the evil of Nazi Germany and the Holocaust, but it wasn't the reason the United States entered war against Germany. It was Germany who declared war against the United States first. If Germany had not, it's possible the United States would have limited itself to war against Japan. If not for Pearl Harbor, would the United States have entered at all? Even if you had presented the evidence to the people of the United States, and the government, that the Nazis were industrially slaughtering the Jewish people (which actually did occur, but was not believed), I doubt a majority of Americans would have gone to war to save the Jewish people.
That may sound like an indictment of the American people. Maybe it is. But it seems a historical fact. America would not go to war to prevent genocides on several occasions. In some occasions that it did, it failed because public support was limited. Somalia, Cambodia, Syria, Ruwana. All mass slaughters where the general feeling is that there is nothing to be done about it, or that the cost would be too high. If tomorrow China started wholesale butchery of it's people, as it did during the Cultural Revolution, I doubt a war against China would begin, due to the perceived cost. You could argue that a slave in Alabama is a lot closer to Chicago than a Cambodian in Phenom Penh, but I wonder. It's possible that those who look askance on America being a world policeman have a distance factor, but I wonder.
None of this is an argument that slavery was not a cause of the Civil War. What it does is shed a light on the fact that a certain degree of revisionism was being perpetrated by both the north and the south after, and even during, the civil war. Maybe it's not even revisionism, but a changing of minds and attitudes. Maybe Lost Cause revisionism is actually a subtle indictment by southerners themselves that slavery was never a good thing to have defended. It's possible that it's an admission that it was indeed a stain and evil. The concern is that it is a whitewashing of history, to justify secession, but it doesn't seem to get very far. Facing slavery was and is one of the challenges facing southerners. Faulkner, now accused of being a Lost Causer, wrote reams on it.
Honestly, if slavery is dropped as defensible by even the lost causers, then the victory of the north in the Civil War is complete, if it was indeed fought over slavery.
The cause of war is a complex bit of historiography. Why did WWI start? An assassinated Arch-Duke? The politics? Failure of diplomacy and an inter-national entity? Or was it simply that the machinery, once started, could not be stopped? The cause of WWII? Was it imperialism and the fight by nations over scarce resources? Was it about power? Was it about grievance? Was it about Pearl Harbor?
The American Civil War has descended and continues to descend into myth. The history is all there, though. But what happens often contradicts what people say. History is people. People have been and continue to be motivated primarily by their passions. Passion over the great evil of slavery. Passion over slight to character. Passion over politics and justice. You see it today, everywhere.