Chapter artwork for The Lord of the Rings book 5 chapter 4: the Siege of Gondor.
This design shows the forces of Sauron, represented by an encroaching crescent moon from the left/east, surrounding Gondor, displayed from a bird's eye view with seven stars. The center of the dark crescent has the Eye of Sauron with flames protruding from it. The center of the eye is a diamond shape, pulled from one of Tolkien's own illustrations of the Eye.
"So now at last the City was besieged, enclosed in a ring of foes."
"The plain was dark with their marching companies, and as far as eyes could strain in the mirk there sprouted, like a foul fungus growth, all about the beleaguered city great camps of tents, black or sombre red.
Busy as ants hurrying orcs were digging, digging lines of deep trenches in a huge ring, just out of bowshot from the walls; and as the trenches were made each was filled with fire, though how it was kindled or fed, by art or devilry, none could see."
—Excerpt from The Lord of the Rings book 5 chapter 4