Rereading the synopsis I copy/pasted into my earlier post, I realize that the way it words it is pretty bad. The idea the was posited by the Demon Queen in the first chapter basically boiled down to "Killing me won't end the war because I'm mostly a figurehead, the wartime economy is postponing the collapse of the human world, we can figure something out to get a different end to the war that total annihilation."

Their main activity has been to spread improved agricultural techniques and nudge the economy of the country at the frontline of the war to become less dependent on the central nations that actually fund their current economy.