I have read this one! It was indeed, as J-Sun says, the city not long after. They used tricks against the beseiging army such as capturing them individually and stencilling DEAD on their forehead with indelible marker. They then released them to lower troop morale. As time went by most of the high ranking enemy bore this mark . I've read a similar one set on another planet with the artist community doing the same to the invading Earth Marines