Code-named "Contraband", a group of Black Americans who had been held as slaves and escaped to the North during the Civil War provided some of the most important spy information of the war. Many of the slaves who escaped during the war actively sought out Union Army officials to tell them about the information they had learned as they traveled north. Some of the former slaves were recruited by the Union to work as trained agents. Frederick Douglass was a former slave who became a vocal abolitionist. There were numerous other men and women who made significant contributions to the Union’s spy data. The information the Union received from the Black Dispatches was the most productive of all the intelligence gathering of the war. Negroes have repeatedly threaded their way through the lines of the rebels exposing themselves to bullets to convey important information to the loyal army of the Potomac.