The monument, which stands across from the Massachusetts State House, is currently surrounded in plywood to protect it while it undergoes restoration to reinforce the sword held by Robert Gould Shaw.
After Sunday's demonstrations turned violent and destructive, the plywood was left covered in obscene graffiti.
"A thousand men signed up just after President Lincoln signed the Emancipation Proclamation, just think about that," said Liz Vizza, executive director of Friends of the Public Garden. "These are men who, if they were captured in the south, would be enslaved or murdered. But this cause was so important to them, they signed up to go fight for their freedom."
The memorial has been vandalized before – with paint in 2012, and the sword was broken off in 2015 and 2017.