Updated

Virginia's Education Department approved a textbook that wrongly claims thousands of black troops fought for the Confederacy.

The agency is now warning schools about the mistake after a fourth-grader's parent discovered the error in the Civil War chapter of "Our Virginia: Past and Present." The parent, Carol Sheriff, is also a history professor at the College of William and Mary.

Sheriff says blacks occasionally took up arms to defend their masters, but it was illegal to use blacks as soldiers in the Confederacy until toward the war's end. None of those companies saw action on the battlefront and most worked involuntarily as laborers

"Our Virginia" author Joy Masoff told The Washington Post that she found the passage on the Internet.