Since <i>exactly zero</i> of the top ten battles of the war were fought on the western front, it is hard to see GCHQ as so useful as is often claimed.<p>Yes, Stalin was also given access to some decrypts. Yes, Stalin murdered or imprisoned ~15 million Soviet "citizens" (a majority citizens of invaded neighbors, but plenty of Russians, too, including his own senior officer corps) before the war. Yes, Russia provided a huge share of the resources to build up Germany's armory before the war. Yes, Russia invited Germany to split Poland with it. Yes, in the final two years the Soviets depended on the US for food, fuel, steel, and trucks. Yes, Stalin had been poised to invade Germany when he was surprised and lost the bulk of his own armory at the outset. Yes, a majority of the Soviet troops killed were not Russian. Yes, the naval war was mostly conducted by the US and British Fleets. Yes, the US was busy in the Pacific theater.<p>Still, the war was mainly a battle to the death between two totalitarian regimes, with the US and Britain harrying at the edges. The Allied bombing, while it killed many, many civilians, utterly failed to stop massive growth of production of tanks and aircraft, right up to the end; that declined only in the final half-year as original German territory was overrun. (Production of pilots failed to keep pace, limiting the aircrafts' value.) It took only a small fraction of German forces to keep the US and Britain fully occupied in Africa, then Italy, and even after D-day. At the end, Stalin had to park and wait months for the Allies to catch up, and spent the time chasing Nazis out of the south.<p>"No Simple Victory", by Norman Davies using material exposed after the Soviet collapse, is an eye-opening resource.