Throughout World War II, numerous tensions existed over how the war was being conducted ranging from the methods used to the over all strategy. Not all of the issues that caused tension had equal effects on the eventual outcomes of the conflict, primarily in the two largest theaters, Europe and the South Pacific. Three particular issues had far greater effects on the conduct of the war or its eventual outcome.
Arguably the most controversial action of the war, which also caused significant tensions of the debate over how the war was conducted, was the decision to drop atomic bombs on Japan. The most obvious concern over whether or not to drop the two prepared bombs should have been about the amount of destruction that would be caused. Instead, probably partly because of the fire bombings that had already occurred, the greatest amount of debate was dedicated to Soviet intervention. For most of World War II the Soviets and Japanese had a non-aggression, however with much urging and prodding, the Americans were able to convince the Soviets to enter the war with Japan, who agreed to enter three months after victory in Europe. When victory in Europe came and the war with Japan seemed to have no end in sights, the Americans became worried that Soviet entry could greatly complicate potential peace talks. In addition to worries over Soviet intervention, there were distinct worries over the possible death toll of a campaign in mainland Japan considering the staggering death tolls on Iwo Jima, Okinawa, and numerous other islands in the South Pacific. Despite not being the primary area of debate, the ethics of using such horrible weapons, however the level to which it was debated is unclear.
In the end, President Truman approved of the use of the atomic bombs. After the first bomb was dropped, the Soviets immediately declared entrance to the war with Japan, sensing that time was running out to assure a Japanese surrender sans Soviet influence, the second bomb was dropped, officially inducing the Japanese to give unconditional surrender. Based on complete speculation, it can be supposed that the decision to use the bombs, aside from keeping Soviet fingers out of Japan shortened the war with Japan by up to two years, saving hundreds of thousands of American lives and probably millions of Japanese lives. The way the Japanese fought to the last man on Iwo Jima and Okinawa, the fervor with which they defended their homeland, would have meant it would be years before the war ended.
Arguably the second most divisive of World War II, and probably the most divisive amongst supreme allied command concerned which of the Axis belligerents should be of prime importance. Key amongst the issues involved in deciding which theater of operation took prime precedence was the fact that while Japan had attacked the United States and Germany had not, FDR knew that if the Americans were unwilling to fight World War II as two front war, Britain would eventually fall,...