There is always something suspect when looking at modern representations of robots and placing them in the context of a pitched fight that looks like trench warfare meets infantry and cavalry. Also, the shield maiden suggests fantasy or medieval style, though that stuff, in the modern or futuristic context of war, is either outmoded or unrealistic.
Not to say this isn't a cool piece of science fantasy art--it's actually tremendous as a sketch--so what I'm getting at is that the story between a cybernetic or robotic empire turned against a small human resistance, while engaging, fails to address technological changes on the battlefield. When you're composing a story of this ilk, you have to remember that steel trumps flesh and computers can out-calculate brains, but that humans are adaptable and tenacious, soulful and ingenious. First order of business is to use an EMMA pulse via a high-altitude nuclear detonation, which fries anything with a circuit and disables many a thing that the robots rely upon. However, if there is a reason this will not work, you'll have to spend time rationalizing anything from alternative methods of microscopic propulsion (like maybe nanotechnology, but even that is a stretch) to some sci-fi convention like a dampening field.
As melodramatic as this image of a confrontation appears to be, it begs to ask how a resistance would be so foolish as to rush into a wall of steel as though that would save them. Again, humans are far more ingenious than this and would not waste time or energy on pitched battles and such. They might use this as part of a diversionary tactic if they were content to just have themselves butchered so one lone saving grace among their ranks can deal a killing blow with the robots preoccupied. It doesn't necessarily add up; historical knowledge of military conventions in place during the middle to Renaissance periods have little to no place in a modern conflict such as this. War is stupid, for sure, but this, to some, just looks even stupider.
I do appreciate the level of detail in the picture. This thing looks like it can be finished into a brilliant picture, digital or otherwise. Despite the anachronisms and suspicious premise, I perceive the energy and grandeur, from the villain's pose to the fire from the sky. This looks like the cover of a science fiction novel--the beginning of one at least--and it may even inspire a sci-fi feature-length cartoon akin to "Gandahar" (aka "Light Years"). Given the context, that's a compliment.
