This section describes a brief period between April and September 1945 that was filled with events of global significance: Allied victory in Europe in May, the successful testing of nuclear weapons in July, Truman’s decision to use such weapons in Japan in August, and Japan’s subsequent surrender. The theme of War and Character features prominently in this section because it mirrors the formative experience that World War I played in his life. The Second World War served as a baptism by fire for Truman’s presidency. The author carries over the juxtaposition of Roosevelt and Truman from the previous chapter in the context of foreign policy. Roosevelt had established relationships with both Churchill and Stalin whereas Truman was a novice

Because the invention of the atomic bomb was so monumental, and its first use in Japan so horrific, “The Summer of Decision” is one of the only sections in which the author engages in historical analysis and employs historiography to offer different theories and interpretations. In contrast, much of the book only contains brief historical vignettes used to situate Truman’s life and to provide a broader background.

The question of the necessity of using atomic weapons in Japan divides into two general camps. The first accepts the official US argument of saving American and Japanese lives by using the bomb and preventing the necessity of a land invasion. The reasons for the Japanese unwillingness to surrender up until that point include two decades of militarism under Hirohito that permeating every part of Japanese society. Revisionist historians argue, by contrast, that the Soviet agreement to fight Japan made at Yalta and confirmed at Potsdam made the use of nuclear weapons unnecessary. Indeed, the Red Army numbered over a million and entered Manchuria hours before the American bombing of Nagasaki. Some historians also suggest that the Americans used atomic weapons to show their power to the budding rival, the Soviet Union. McCullough argues against the latter suggesting that there is no direct evidence of it. However, the growing tensions with the Soviet Union over the postwar order in Europe provide indirect evidence that the weapons may have had this secondary purpose.

McCullough discusses Soviet-American relations only from the American point of view. For example, the author quotes Stalin but does not explain Stalin’s motivations for disagreeing with his Anglo-American counterparts. American foreign policy did not recognize legitimate Soviet security concerns. Russia had been invaded by Poles in the 17th century, France and Britain in the 19th century, and Germany during World War II. The geopolitical situation in Europe was of direct relevance to the Soviet Union on a continent it shared. In contrast, the US was located on a different continent surrounded by oceans and weaker neighbors. Also, the Anglo-American side took its influence in Western Europe for granted yet questioned the Soviet presence in Eastern Europe—in part for the legitimate reason that Western European counties were governed democratically. Additional historical context texts would be helpful here.