This Euro-American war was certainly not the war which is being waged while I write this book, in spite of obvious similarities. At this time the Germans had recovered from that extravagant hooliganism which had turned the world against them in an earlier period. They had in a manner reverted from Nazism to the more respectable Prussianism. Other facts also show that this was not our present war. Both India and South Africa had left the British Empire and were already well-established independent states. Moreover, weapons were now of a much more lethal kind, and the American coast was frequently and extensively bombarded by fleets of European planes. In this war Scotland had evidently become the economic centre of gravity of Britain. The Lowlands were completely industrialized, and huge tidal electric generators crowded the western sounds. Tidal electricity had become the basis of Britain’s power. But the British, under their effete financial oligarchy, had not developed this new asset efficiently before the German attack began.
This is another of the Retro Hugo finalists for Best Novel. I'd read Star Maker and Last and First Men by the same author; Darkness and the Light is on the same lines, but not as good. It's a story of two parallel future histories of humanity, which bifurcate at a decision point where a movement of spiritual and political awakening in Tibet either is crushed, in the timeline that leads to the human race being defeated by rats, or leads the world to new levels of civilisation, in the timeline that ends with humanity's transcendence. You can't accuse Stapledon of having small ideas; however, this is not really a novel, in that I don't think there is a single named character or a line of actual dialogue. There are six better-known Stapledon books (the two above-named, also Odd John, Sirius, Last Men in London and Nebula Maker) and there are good reasons why this is not in the top half dozen. It won't get a high vote from me, but you can get it and decide for yourself.