I am not too sure about that. If you look closely (under high setting), each man is till individually and distinctly clothed, the horses of the same cav unit looks different slightly, and the legs animation suggest to me that 3D rendering is still done.. it may look like 2D sprite at low setting, but I am not too sure if the rendering is like STW or MTW.

What i am suggesting is to switch to STW/MTW type of graphic processing at zoom-out view.