A Confederate heritage group says its free-speech rights were violated when a landowner removed a billboard promoting Southern history near the famed Darlington Raceway. The Sons of Confederate Veterans plans to demonstrate at the State House next month and buy radio advertisements to complain about losing its billboard on U.S. 52, about two miles from the racetrack. “This is the most chilling thing I’ve seen against freedom of speech,” spokesman Don Gordon said. The Sons of Confederate Veterans bought the billboard this spring in response to remarks by a NASCAR executive about the rebel flag. The billboard featured a Confederate...