Hi Ken, I'm sure when you were asking for comments you might have been secretly wanting extended comments. For your sake, I'll give you on.
Personally, I think the piece is great. However, for exam purposes I'm a little worried. I believe that you could have softened the shift in tone on his face, to clean things up and keep that rough feel to it. His position is a bit awkward. What's he doing is also awkward. I'm also assuming that that is camo paint on his face now that I look at it in more depth. His body part is a little incoherent, and stronger shadows on the right side of his face could have made the lighting feel more intense. The way the background has these plumes of smoke is amazing, however, the scale of those dip down the depth of your piece, thereby making it shallow. The way the smoke from the shell explosions drifts is well done, but you could have added more to depict a stronger scene in the background. You could add two Jets flying off behind the Washington Monument. I think you should have worked on a wider canvas, so that you could add more detail to it. For example, a structure lit by red flares could have given you good lighting. I think there are structures adjacent to the Monument, like to the side of your piece. Perhaps an apocalyptic derelict type of structure? And well, that's about it. Hope I kinda helped.