The Oakwood cemetery in Raleigh, North Carolina, was vandalized. Headstones in this Confederate cemetery were toppled and defaced with spray painted "KKK", "white supremist", "slavery" and other graffiti.
Cemeteries are a place of rest for our ancestors. A place of peace and a place of remembrance. It's a place of history. Likely, most of those people buried in this cemetery are someone's ancestors. If someone disagrees with what the people in a cemetery lived for and died for, they should just stay away, not vandalize it. If everyone vandalized the headstones of those they disagreed with, every single headstone in the entire world would be damaged. No matter what their political orientation and no matter how they lived, how would you like it if your ancestors' headstones were damaged?
In addition to common courtesy, everyone needs to keep in mind the time these people lived. Every person, if they must be judged, must be judged against the time they lived. Before the end of the Civil War, a large percentage of those who lived in the southern United States and other locations, believed it was their right to own slaves. That was the time they lived in. Today, we know it's an abhorrent belief and practice. However, this is how people lived back then, and not just in the southern United States. This happened around the world. Many of the great men who founded the United States owned slaves. This doesn't mean you shouldn't honor them for what they did. Point out their imperfections and learn from them. Don't vandalize their memorials.
A large percentage of people living in Germany fell in line behind the Nazis. Does this make every single German alive during World War II a criminal? Absolutely not.
The same thing is happening in the lands taken over by or sympathetic to violent Islamist extremism. They are destroying important historical landmarks because they destroy anything that doesn't support their world view.
This is our history. We need to remember it. If we are allowed to destroy history, it will be forgotten and will likely be repeated. Remember our dead. Honor them. Learn from them.