FINAL BLACKOUT (The Garland library of science fiction)

As the great World War grinds to a halt a force more sinister than Hitler's Nazis has seized control of Europe and is systematically destroying every adversary -- except one.In the heart of France a crack unit of British soldiers survive, overcoming all opposition under the leadership of a hardened military strategist highly trained in every method of combat and known only as "The Lieutenant."Ordered to return to British Headquarters, the Lieutenant is torn between obeying the politicians in London or doing what he knows is right for his country, regardless of the price.