This piece has a pretty good sense of depth. Composition looks good, I can easily pull out the general of this army. I think that if you're going copy and paste some soldiers, I can see you changed the faces, but there could be some shadow adjustments as some of the characters fade away, such as the warriors in white armor. But one thing that really stuck out is the perspective. You've got the characters down right, so it took me awhile to see it, but the horizon line seems to be about where their heads are. If that is the case, we should be looking down on the cannon. But right now, it appears to me that I am looking up at it.