I don’t care what Lee thought on any topic any more than I care what Goering thought about how best to clean up the mess he helped create. The wave of civil war monuments really picked up speed in the 20s when the klan was making a resurgence and then had a second wave of popularity beginning in the late 40s when the Dixiecrats started to mobilize against integration, first of the US military and then of our schools. It was a white supremacist movement. The statue of Lee in Charlottesville, for example, coincided with a gift of $1,000 to UVA from the KKK.
In fact the efforts to take down statues honoring the confederacy, isn’t revisionism, it is an attempt to correct a campaign of historical revisionism based on white supremacy.
In order to make it pass the smell test, the movement pushed some lies. The first was to focus only on military tactics and battles, not the social movements behind those battles. Another was that the war wasn’t about slavery, although every state that seceded mentioned slavery in their declaration. And another lie was that Lee was an honorable and reluctant warrior.
Far from seeing Lee as a worthy and honorable adversary, Grant hated Lee. He felt that Lee was
“setting an example of forced acquiescence so grudging and pernicious in its effects as to be hardly realized.”
While Lee was a general his army committed a number of atrocities against black people, including enslaving any black person unfortunate to be caught by his army as it marched to Gettysburg. When Lee proposed a prisoner exchange with Grant, Grant made it clear that it would have to include captured black union troops. Lee declined, the black troops weren’t prisoners, but property
Lee was also a cruel slave owner, even for the time period. In one case, a 19th century Virginia court ruled against Lee in favor of his slaves. All this info is referenced in the link below, but there is quite a bit of scholarship that undoes the myth of Lee as a warrior Santa Claus.
And Lee is just one confederate traitor, there are hundreds of statues to his comrades in arms. We let the losers write history and we’re still letting them write it.
ETA: When Lee was university president he declined to punish students accused of raping students from a black girls school nearby, or of participating in lynching. Why on earth would we want a statue of someone like that in our cities?