The great facts of World War II include the Allied insistence on the declared unconditional surrender of the Axis powers and the American unleashing of atomic bombs to bring an end to the war in the Pacific. Some scholars charge that the demand for unconditional surrender lengthened the war, but this misinterprets the situation. Neither Hitler nor the Japanese leadership were open to a considering any surrender until the very end. German cities were reduced to rubble and Hitler’s armed forces destroyed before he recognized that the war was lost. Japanese leadership accepted surrender only in August 1945, with the nuclear incineration of Hiroshima and Nagasaki and the Russian invasion of Manchuria. The treatment of prisoners of war by the belligerents varied. On the European Western Front, it essentially conformed to the humane standards set by the 1929 Geneva Conventions. On the Russian front, it was a war of extermination. Of the 5.7 million Soviet military taken prisoner by the Germans, 3.3 million died. In the Pacific War after April 1942, the Japanese took few prisoners. Once Americans realized the murderous fate that awaited those whom the Japanese overcame in combat, the Americans gave no quarter to the Japanese.

The study of causes is fundamental to the historian’s craft. Historical explanations involve asking “Why?” In their interpretations, historians must choose the time frame within which to study the causes of an event. After first finding immediate causes, historians can look for longer-term ones. Choice of a broad time frame may demonstrate that the event being studied was shaped and influenced by longer-term processes than were first perceived. Finding a multiplicity of causes, the historian will need to order them in terms of priority. This chapter shows that while most historians of the Hiroshima decision dwell on Truman and the last months of the war, other historians have found longer term causes compelling. Truman, it is argued, inherited Roosevelt’s policies and was driven by the momentum behind them, especially the longstanding readiness to use the bomb and adherence to the unconditional surrender policy.