What all this reminds us is that in order to defeat an enemy they routinely denounced as barbaric the Western powers had made common cause with an ally that was morally little better—but ultimately more effective at waging total war.

“The choice before human beings,” George Orwell observed in 1941, “is not . . . between good and evil but between two evils. You can let the Nazis rule the world: that is evil; or you can overthrow them by war, which is also evil . . . Whichever you choose, you will not come out with clean hands.”

Orwell's Animal Farm is nowadays revered as a critique of the Russian Revolution's descent into Stalinism; people forget that it was written during the Second World War and turned down by no fewer than four publishers (including T. S. Eliot, on behalf of Faber & Faber) for its anti-Soviet sentiments. Nothing better symbolized the blind eye that the Western powers now turned to Stalin's crimes than the American Vice-President Henry Wallace's visit to the Kolyma Gulag in May 1944.