Good anime series. Only one season, so I suspect you’ll have read the Manga to see how it ends (though the anime reaches a perfectly good stopping point). There’s lots of neat historical parallels, though for each one there’s an example of how the series diverges, so don’t read too much into that. It’s by no means an allegory, and many aspects are more characteristic of WWII (such as the aerial component), though there’s no Hitler. I’m impressed by some of the little things (like the French starting the war without helmets).
On a more personal scale, the protagonist has a definite Job thing going on between herself and God. Though to be sure, Job wasn’t such a bitch-on-wheels.