I think for episode 7 is a somewhat on the serious side. Everyone knows that war is destructive. If you look back to World War I and II, you know what I'm talking about, but this seems to be worse because, well everything is almost gone. Talking about a post-apocalypic world...
But remember, war-robots can be evil...
Also, the ED was a killer in this super-serious episode... reminds me of some other anime that done the same effect.