The Gangster Disciples, Latin Kings and Vice Lords were born decades ago in Chicago's most violent neighborhoods. Now, their gang graffiti is showing up 6,400 miles away in one of the world's most dangerous neighborhoods -- Iraq. Armored vehicles, concrete barricades and bathroom walls all have served as canvasses for their spray-painted gang art. At Camp Cedar II, about 185 miles southeast of Baghdad, a guard shack was recently defaced with "GDN" for Gangster Disciple Nation, along with the gang's six-pointed star and the word "Chitown," a soldier who photographed it said. The graffiti, captured on film by an Army...