Picasso's Guernica, the one posted by Cosmic, may be the most horrified painting, and thereby, for some, the most horrifying. It is one of the most complex and therefore provocative pieces of art I know of. Since it is far from representational or realistic, it involves a lot of response from the viewer to make sense of it, I think.
Ref. brad's Navy poster, when the first Gulf War started, and then later the second, the people called into service got older and older, and I got really worried. I'd been through one disputed war and wasn't eager. I kept having dreams about being recalled. Once a swabby, always a swabby.