August 6th and 9th, 2010 marked the 65th anniversary of the bombings of Hiroshima and Nagasaki, respectively. These two dates remain the only times nuclear weapons have been used for their original intended purpose: to destroy population centers along with an enemy’s ability and desire to wage war. For seven decades, the world has debated the wisdom and morality of the use of these weapons. To better understand the reasoning at work in the minds of Allied leaders and war planners, it is important to look at the events leading up to these August, 1945, dates and consider one of the greatest ‘what if’ scenarios of not just the Second World War, but of all modern military history.
By the summer of 1945, the Empire of Japan had ceased being a threat in most areas of the Pacific theater of war. Okinawa, only 340 miles from mainland Japan, was secured by U.S. Army and Marine Corps divisions by the end of June. While significant Japanese ground forces remained active in China and Korea, the Allies had destroyed the Imperial Navy over the course of the previous three-and-a-half years, leaving her coastal cities open to shelling from the battleships and heavy cruisers of the U.S. and British Pacific fleets. The Japanese air force, while numerically still a presence, was all but grounded due to a lack of fuel. Every major city in the Japanese home islands had been at least partially leveled by daily U.S. Army Air Corps bombing raids. The Japanese merchant fleet, once one of the world’s largest, had ceased to exist. The island nation was cut off.
Yet, the remains of the once-vast empire fought on. There was a strong belief among the military leaders of Japan that a successful invasion of the four main Japanese home islands would mean the end of the nation as a distinct cultural entity. The hardliners believed that surrender was not an option and that an Allied invasion required the entire population to fight to the point of extinction. There were voices of moderation in Tokyo, one of them being the Emperor of Japan. However, tradition demanded that he remain officially silent. He had made his desire for a negotiated peace clear, however, in private discussions with his ministers. The Emperor wanted the Soviet Union (who was not yet at war with Japan) to act as a mediator between the warring powers in the Pacific. However, he also wanted some sort of concrete victory in order to gain leverage during the negotiations. By the end of June, 1945, it was clear there would be no great Japanese victory on Okinawa or anywhere else. Furthermore, the Soviets were not interested in brokering a deal of any sort: Josef Stalin had his own plans.
Meanwhile, the war in Europe ended in early May, 1945. While the occupation of Germany and Eastern Europe and post-war actions of the Allies had been discussed on multiple occasions since early in the conflict, there were still many details which needed to be sorted out. Beginning on July 17th, leaders of the United States, United Kingdom and the Soviet Union met in Potsdam, Germany to discuss both the issues of occupation and the war in the Pacific. President Harry Truman, who had come to the office after the death of President Roosevelt in April, arrived at the conference with monumental but secret knowledge: an atomic bomb had been successfully tested in the New Mexico desert just one day before the beginning of the conference. Three years of super-secret work and billions of dollars had resulted in the construction of the most deadly weapon in human history. Yet only a handful of people not working directly on the device knew that it even existed. Truman himself was not made aware of the bomb’s pending completion until after Roosevelt’s death in April, 1945, despite the fact he had been the Vice-President.
Truman met with Prime Minister Winston Churchill on July 21st, at which time the two agreed on the use of the weapon. Soviet Premier Stalin was not told until July 25th, a delay which made him privately angry but only because his advice on the weapon’s use was not sought as Churchill’s had been. In truth, Stalin knew about the new weapon from information provided by Soviet spies working inside the Manhattan Project.
On July 26th, Truman, Churchill and President of the Republic of China Chiang Kai-Shek issued the Potsdam Declaration, a statement which called for the surrender of Japan. It was an ultimatum; as the Declaration stated, the alternative for Japan was “prompt and utter destruction.” The Declaration was transmitted via radio, leaflets were dropped over the home islands, and it was conveyed diplomatically by Swiss intermediaries. Newspapers in Japan were the first to announce that the government rejected the Declaration, although it is doubtful they had any official word on which to rely. On July 28th, Japanese Premier Kantaro Suzuki announced that since the Declaration was just a rehash of earlier Allied demands, it would be met with mokusatsu, a Japanese word that roughly translates to the phrase “to treat with silent contempt.” Thus, the Declaration was not so much rejected as it was ignored.
Much has been made of the Premier's words by historians, with some suggesting that his failure to issue an outright rejection indicated a willingness to negotiate. However, there is no strong evidence to support this. The faction in Tokyo that was willing to negotiate an end to the war wanted to deal from a position of strength. Even the Emperor, portrayed for more than seven decades as a man who wanted nothing more than peace, believed that strong resistance to an Allied invasion of the Japanese home islands would open the door for more balanced negotiations.
Even the Emperor, subject to deification by the Japanese population, could not see the events unfolding across the Pacific. When news reached Washington that Tokyo was unwilling to surrender, President Truman took the decision to use one or more nuclear weapons against Japanese cities. On August 6th, 1945, the weapon known as Little Boy was detonated over the city of Hiroshima. On August 9th, the weapon called Fat Man was detonated over Nagasaki. The immediate effects of the blast and short-term intense radiation exposure killed more than a quarter-million people over the next four months. The plan called for the continued use of nuclear weapons against one city after another until the Japanese surrendered. However, on August 15th, the Japanese government announced its surrender. Three weeks later, on board the battleship USS Missouri, the instrument of surrender was signed by representatives of the Japanese government and the Allied powers. The most destructive war in the history of mankind was over.
But what if the two atomic bombs had not been used? What if technical difficulties had delayed the production of a working nuclear weapon for several more years? Or, what if President Truman had come to consider nuclear weapons morally reprehensible and forbade their use against any target? While the latter scenario is unlikely (Truman said repeatedly that he did not hesitate in his decision to use the bombs against Japanese targets nor did he regret it later), the former could very well have taken place.
For the millions of Americans and their allies in uniform in 1945, an invasion of Japan seemed the next logical step in a bid to bring the Second World War to an end. What few of them knew, and what many people still do not know today, is that planning for the invasion of Japan was well underway. In fact, the primary plan for the invasion had been circulated in early May, 1945. It took into account the fanatical resistance the Japanese military had put up in the face of invasion of even the smallest bit of land in the Pacific. It was this plan which President Truman and Prime Minister Winston Churchill had in their minds as they discussed the use of nuclear weapons. As you will see, there were no easy alternatives.
The planned invasion of Japan was known as Operation Downfall. It was broken down into two major operations: Operation Olympic, the invasion of Kyushu, the southernmost of the main Japanese islands. The operation would begin on X-Day, Thursday, November 1st, 1945. Operation Coronet was the planned invasion of the Kanto Plain south of Tokyo. Y-Day was set at March 1st, 1946. The southern third of Kyushu would be used as the staging area for this invasion.
The resources being set aside for these two operations were unlike anything seen up to that point in the war. The landing force for Olympic would consist of 331,000 American soldiers and 99,000 Marines. Coronet could consist of roughly the same number of Americans, many of them belonging to divisions that had fought in Europe. Three divisions of U.S. Marines would participate in each landing; that was the entire Marine Corps as it existed in 1945. These numbers do not include the tens of thousands of British, Australian and New Zealand troops which would have taken part in Operation Coronet.
In the air would have been the Fifth, Seventh and Thirteenth Air Forces of the U.S. Army Air Corps, along with the Eighth Air Force just transferred from Europe. With them would have been the Tiger Force of the RAF Bomber Command and the Australian First Tactical Air Force. The waters surrounding the invasion beaches would have contained the largest naval armada ever assembled. The U.S. Third, Fifth and Seventh fleets, comprised of 56 aircraft carriers, 20 battleships, over 50 cruisers and hundreds of smaller warships would have been joined by the entire British Pacific Fleet made up of 6 fleet carriers and their escorts. This represented 90% of the world's naval ships as of 1945, all concentrated in one area. And this tally only includes the warships. Thousands of cargo ships and troop transports would have been on the scene as well, making the Allied of invasion of Normandy in June, 1944 look small in comparison. The invasion beaches had already been given names such as Cadillac, Zephyr, Mercury, and Packard, all automobile manufacturers.
The Japanese Army had large numbers of troops in Korea and China in 1945, all of them essentially trapped in position with no hope of resupply or rescue. There were, however, hundreds of thousands of soldiers stationed in the Japanese home islands. Japanese defense planners, like the Allied war planners, understood the importance of using Kyushu as a base of operations. Thus, they had stationed 600,000 regular army troops there. There were also 5,000 aircraft assigned for use as kamikaze aircraft, the suicide planes that had caused so much trouble for the U.S. Navy during the last year of the war. And although post-war estimates vary, there were as many as 12,000 aircraft set aside in reserve status, although the airworthiness of these planes is questionable.
The Tokyo Plain, the landing area for Operation Coronet, was defended by 560,000 troops. This did not include the vast number of civilians that were being armed with everything from modern rifles to wooden spears. The Japanese Navy, such as it was, still had 350 midget submarines ready for use, 1000 manned torpedoes and over 800 suicide boats. Like the aircraft designated for kamikaze work, the seaworthiness of some of these naval vessels is in doubt. However, the intent was to use them while the Allied invasion fleet was still far out at sea. While the powers in Tokyo knew that they could not ultimately repel an invasion, it was hoped that the operation could be made so costly that Allied leaders would be willing to negotiate a ceasefire, giving the Japanese the ability to negotiate from a position of strength.
For two generations, historians have debated the number of casualties (both dead and wounded) that would have resulted from an Allied invasion of the Japanese home islands. Even military leaders of the day could not agree on a casualty projection. The last study done during the war, created by Secretary of War Henry Stimson's staff, estimated that conquering Japan would cost 1.7 to 4 million American casualties, including 400,000 to 800,000 fatalities, and five to ten million Japanese fatalities. The total number of American deaths, on the low end, would have been more than the total number of American war dead experienced to that point in the war, both in the Pacific and Europe. Keep in mind that while American and Allied forces fought on Kyushu and the Tokyo Plain, the Army Air Corps would have continued to fire bomb Japanese cities, thus increasing the total civilian death toll.
Nearly 500,000 Purple Heart medals were manufactured in anticipation of the casualties resulting from the invasion of Japan. To the present date, all the American military casualties of the sixty years following the end of the Second World War—including the Korean and Vietnam war—have not exceeded that number. There are still so many in surplus that combat units in Iraq and Afghanistan are able to keep Purple Hearts on-hand for immediate award to wounded soldiers on the field.
There would also have been political consequences to consider. In early August, the Soviet Union declared war on Japan and invaded parts of Manchuria and the Kuril Islands, the northern part of the Japanese island chain. It is very likely that Josef Stalin would have ordered his forces to continue moving down the island chain as the rest of the Allied forces moved up the chain from the south. It is very possible that Japan would today be two nations, much like North and South Korea. The effect that would have had on the world, both economically and culturally, can not be measured.
The debate over the use of nuclear weapons against Japan in August, 1945, will continue as long as those events are remembered by human beings. One can only hope that future events will never be so horrendous as to cause Hiroshima and Nagasaki to fade from out collective memory.