This is the most ambitious and important book from Yale University Press’ invaluable series of documentary histories drawn from the Soviet archives. Winston Churchill, Franklin Roosevelt, and Joseph Stalin exchanged 682 messages between Nazi Germany’s attack on the Soviet Union, in June 1941, and Roosevelt’s death, in April 1945. Three-quarters of them are published here. Beyond the messages themselves, what makes this volume so valuable are the editors’ brisk and penetrating historical introductions and the context they provide for each message: the author’s mood and calculations, the political advice each leader was receiving, and sometimes the hidden diplomacy complementing the message. Scarcely any aspect of World War II has been more thoroughly written about than the relationships among these three leaders, but documenting their wartime communication in such detail gives new depth to this history. Stalin’s more cordial attitude toward Roosevelt than Churchill, for example, is unmistakable, as is the subtle shift in the dynamic among the three in Stalin’s favor beginning in 1943.