Some of those drawings are little more than diagrams - attempts at sketching out the topography and arrayed forces in a given battle; they come with written notations to clarify things for the engravers.
But many have real artistic merit. You can’t help but admire, for instance, the subtlety of observation and the variety of hatched pencil marks in Charles Soule Jr.’s “Camp Sherman’’ or Frederic Schell’s “Siege of Vicksburg: Soldiers at Work on the Fortifications.’’
Schell’s “Chattanooga Valley Sketched from Lookout Mountain after Sherman’s Victory’’ is a rare rendering in ink wash. It shows the battlefield from atop the mountain, the haze of the day obliterating almost all signs of the massacre that had just taken place.