It's not like people won't learn about the Civil War in America, and it's not like removing these statues will change that history. What it does is say "We're not celebrating this anymore," and let's be clear, these were always about celebrating, and not memorializing. These statues were almost exclusively put up to revel in past glory, and not to say "this was horrible and should never happen again."
The vast majority of these monuments went up in the period between 1895 and 1914. Some other key events that occur in that period:
The rise in Jim Crow Laws -
During the Reconstruction period of 1865–1877, federal laws provided civil rights protections in the U.S. South for freedmen, the African Americans who had formerly been slaves, and the minority of blacks who had been free before the war. In the 1870s, Democrats gradually regained power in the Southern legislatures, having used insurgent paramilitary groups, such as the White League and the Red Shirts, to disrupt Republican organizing, run Republican officeholders out of town, and intimidate blacks to suppress their voting. Extensive voter fraud was also used. Gubernatorial elections were close and had been disputed in Louisiana for years, with increasing violence against blacks during campaigns from 1868 onward.
In 1877, a national Democratic Party compromise to gain Southern support in the presidential election resulted in the government's withdrawing the last of the federal troops from the South. White Democrats had regained political power in every Southern state. These Southern, white, Democratic Redeemer governments legislated Jim Crow laws, officially segregating black people from the white population.
Foundation of the United Daughters of the Confederacy -
The UDC was established in September 10, 1894 at Nashville, Tennessee, by Caroline Goodlett and Anna Raines. According to the author Kristina DuRocher, the stated aims of the organization included "creating a social network, memorializing the war, maintaining a 'truthful record of the noble and chivalric achievements' of their veterans, and teaching the next generation 'a proper respect for and pride in the glorious war history'."
In 1896, the organization established the Children of the Confederacy to teach the same values to the younger generation, through a mythical depiction of the Civil War and Confederacy designed to rewrite history. According to DuRocher, "Like the KKK's children's groups, the UDC utilized the Children of the Confederacy to impart to the rising generations their own white-supremacist vision of the future."
UDoC had a hand, as bfv noted, in raising a lot of these monuments. They're still around, actually, as a certified 501(c) non-profit.
Plessy V. Fergusson - This US Supreme Court decisions upholds the "Separate but equal" segregation in the states.
The rise in monuments is correlated with a continued loss of rights for black people in the former Confederate States (and also in the rest of the Union, but to a lesser extent). But why the sudden drop in 1914? WW1. Metal was too precious to be used for monuments.
The other big jump in monuments that you see on the graph comes right after Brown v. Board of Education, which finally strikes down the Plessy v. Fergusson decision, and can be counted as one of the beginnings of the Civil Rights movement in earnest.
It's almost as if the white supremacists in government at the time in these places were putting up more monuments to say "You Will Not Replace Us." Sound familiar?
What I'm trying to make clear is that these statues were NEVER about "honouring history", or "memorializing the loss of a generations of southern men," (which indeed the Civil war was one of, if not the bloodiest wars the US has ever gotten itself into). These statues have always been about white people saying "You will not replace us." Or, to bring back an old phrase, "the South Will Rise Again"
And even if we give people the benefit of the doubt and say that these statues could be used as ways to honour history and memorialize, The fact of the matter is that that is not how they are being used by the white supremacists and neo-nazis of our current time.
Okay, can I just say how weird it is that Robert E. Lee is this huge figure in post-war white supremacy? Like, The dude was this close to fighting for the North, and was milquetoast at best about the concept of slavery. He fought because he loved his state of Virginia, and Virginia was on the confederate side - that's just how it was.
Not only that, after the war he was actively involved in reconstruction efforts, and was an advocate of reconciliation. Just reading the section on the Wiki about his life Post-Bellum makes it clear that his values and the values of people like those who marched in Charlottesville are totally at odds.