hmmm.. i think that you tried to compose it correctly. You followed the rule of thirds perfectly, but i don't feel that the composition is right. Maybe if you backed away from the cannonballs a little bit and put the pile of cannon balls off to the right or left of the frame. The picture now is a little plain, maybe mess with the tones a bit to juice it up a little. Sometimes changing little things can make all the difference. Remember this is all constructive criticism and i'm simply trying to help you for your pictures in the future.
Wow Dan's back
this guys famous man and he's spot on. I think to me it looks like it's cut off, so a step or two back will do. (unless you were on the edge of a cliff)