World War II is the good war, the one where evil was defeated. But there was always a rub. The great ally of England and America was not a democracy. It was a totalitarian power. And it did the heavy lifting, which is to say that Stalin's Red Army carved up the German Wehrmacht. It engaged, at a horrific cost, in the big battles that settled the course of the war that Stalin's original gamble—conniving with Hitler and his henchmen to conquer and divide Poland, the western Ukraine and the Baltic States in 1939—had helped bring about. It was the Red Army, in short, not the American or British one, that fought the battle of Berlin in the spring of 1945 to liberate the German capital from the Nazis, a pivotal moment closely covered by Michael Dobbs in his forthcoming book Six Months In 1945.

Winston Churchill had said he he would "sup with the devil" if it would help bring about victory. So he—and Franklin Roosevelt—did. They allied themselves with Stalin, even pretended, at least publicly, that he was a fine man and the Soviet Union an even finer place. Now, with the release of numerous documents from the National Archives about Stalin's murder of over twenty thousand Polish officers and intellectuals in the Katyn forest in 1940, we know in even more detail just how far they were prepared to go to extol and defend the Soviet Union.

Stalin's aim was to break the spirit of the Polish nation, to destroy its governing class. The Nazis discovered the graves in the spring of 1943 and tried to blame the massacre on the Soviets. Nazi propaganda minister Joseph Goebbels hoped the announcement would cause dissension among the wartime allies. But Churchill and Roosevelt were having none of it. England had gone to war over Hitler's invasion of Poland in September 1939. Churchill and Roosevelt didn't want to disrupt relations with Stalin, who was always accusing them of trying to cut a separate peace with Berlin. What Katyn indicates, I think, is that the West had effectively given up on Poland's freedom far before the Yalta conference.

All along Stalin was intent on installing his Polish creatures based in Lublin as a postwar communist government. The Polish government in exile in London, by contrast, wanted to investigate the Katyn massacres. Roosevelt's response? "I am inclined to think that Prime Minister Churchill will find a way of prevailing upon the Polish government in London in the future to act with more common sense," he wrote to Stalin, and the British, as the AP further notes, were not inclined to press the matter, either:

"We have been obliged to . . . restrain the Poles from putting their case clearly before the public, to discourage any attempts by the public and the press to probe the ugly story to the bottom," wrote Owen O'Malley, Britain's ambassador to the Polish government in exile, in a May, 1943 letter. "We have in fact perforce used the good name of England like the murderers used the conifers to cover up a massacre."

In 1944 Kathleen Harriman, the twenty-five year-old daughter of American ambassador to Moscow W. Averell Harriman, traveled to western Russia to visit the Katyn site, a visit well described by Allen Paul in his meticulous book on the executions. She concluded that the Nazis had committed the atrocity. She had been spun by her Soviet handlers. Her father wasn't going to disagree—he had been sent to Moscow to maintain smooth relations, though he tolerated his assistant George F. Kennan, who took a bleak view of Stalin's intentions. American POWs had sent a coded message in 1943 that Russians were responsible, but it didn't make, or was not allowed to make, an impression. It wasn't until the 1950s that Congress, in the form of the "Madden Committee," began taking a second look at the Katyn massacre.

On the basis of the new documents, it seems abundantly clear that Roosevelt and Churchill entertained few illusions about what had actually occurred in the forest of Katyn. The two Western leaders were engaging in a brutal act of realpolitik. With Stalin's forces overrunning Eastern Europe and the Western allies unwilling, or at least reluctant, to sacrifice the lives of their own troops to attack Berlin, they had a very weak hand to play. Now, decades later, it is even clearer just how many conifers they were prepared to use to disguise the actions of one of the most murderous tyrants in history.