Nuclear attacks against Japan

Why the Atomic Bomb?

Why did the US drop the atomic bomb? The decision was controversial at the time, with the decisionmakers knowing less than we do today, both on the effects of nuclear weapons, and on the internal Japanese arguments about conditions under which they would surrender. It has been suggested that the U.S. Strategic Bombing Survey said the Japanese would have surrendered without the use of nuclear weapons, but the actual report emphasizes that opinion is made with the benefit of hindsight.

With the benefit of hindsight, it appears that the twin objectives of surrender without invasion and reduction of Japan's capacity and will to resist an invasion, should the first not succeed, called for basically the same type of attack. Japan had been critically wounded by military defeats, destruction of the bulk of her merchant fleet, and almost complete blockade. The proper target, after an initial attack on aircraft engine plants, either to bring overwhelming pressure on her to surrender, or to reduce her capability of resisting invasion, was the basic economic and social fabric of the country. Disruption of her railroad and transportation system by daylight attacks, coupled with destruction of her cities by night and bad weather attacks, would have applied maximum pressure in support of either aim.

Some "revisionists" have suggested Hiroshima was supposed to be an unmistakable signal to Stalin to play along diplomatically with the Americans who planned to rule the postwar world. Many have asked whether some sort of demonstration explosion should have been made, in order to frighten Tokyo without killing so many people. The option was considered, but with only two bombs available Truman decided instead to drop millions of leaflets upon Hiroshima and Nagasaki warning people to leave immediately, and at the Potsdam Conference he explicitly warned Japan it must surrender immediately or be hit with terrible force.

The civilian government in Tokyo wanted peace on conditional terms, but that was impossible because of Roosevelt's policy of "unconditional" surrender, and because the civilians did not control Japan's decisions--the Army did (in the name of the Emperor.) It is often assumed that Hiroshima caused Japan to surrender. Perhaps; but simultaneously the Soviet Union declared war, invaded Manchuria, and crushed the Japanese army there. This ended Japan's feeble hopes for a negotiated peace and proved conclusively that the Army could no longer defend the nation. Even after Hiroshima and the invasion of Manchuria the Army and Navy wanted to fight on, while the civilians wanted to give up. The decisive move was the unprecedented intervention of Emperor Hirohito, who opened negotiations. With Roosevelt gone, the Americans redefined "unconditional" to allow continuance of the Emperor. Hirohito then broadcast an order to the nation and its armed forces to surrender, which was immediately obeyed.

The decision to use nuclear weapons

There was no consensus, among the small number of senior military leaders aware of the bomb development, about the separable issues of military effectiveness of such attacks, and the ethics thereof. While the casualties that would actually be caused by nuclear attacks were not known, the fire-bombing of Tokyo probably caused a greater number of casualties.

The first bomb to be used, a uranium fission device of the "gun" type code-named LITTLE BOY, had not been tested; only theoretical calculations of effect were available. Physicists involved in its development were certain it would work, but less so about the plutonium implosion technology in the second bomb. In the TRINITY test in New Mexico, an implosion device of the type used on Nagasaki was tested, and better data was available.

From the TRINITY experience, however, it was clear that a nuclear explosion would be qualitatively different than any previous attack, and would have great psychological impact. Nevertheless, there were both military commanders, and scientists that worked on the bombs' development, that preferred such measures as an initial demonstration, for the Japanese, on an uninhabited target. Other commanders and scientists believed that the shock value of the weapons would contribute to the ending of the war. Further complicating the situation was that the new President, Harry Truman, had not been informed of the bomb development while Vice President, and had a short time to make the decision.

The U.S., in anticipation of a possible nuclear attack, had bombed four cities, including Hiroshima and Nagasaki, less than other targets. This had two purposes: allowing better assessment of the weapon effects, and also having a greater shock value.

An argument against using these weapons was that Japan was clearly struggling under conventional bombings and the submarine blockade. Unfortunately, the U.S. had no sources inside the Japanese government, which would confirm that there was a stalemate between a hard-line faction that believed it appropriate to fight to the last Japanese, and a faction that was willing to examine a peace. The peace faction had come into being with the loss of Saipan and the resultant fall of the Tojo government, but the Allies had no hard information.

The primary argument was to use a radically different attack with the purpose of breaking the will of Japan, which actually was unlikely to affect the hard-liners. A secondary consideration was that the U.S. was planning a land invasion of Japan, with the first phase, Operation Olympic scheduled in October 1945, with the target of Kyūshū, which was under the command of Second General Army. That organization, comparable to an Allied army group, had its headquarters in Hiroshima Castle.

The U.S. Navy had very little to do with the atomic bomb decision. Having temporarily lost 5 of its 11 big carriers at Okinawa, it did not want to face the Kamikazes again during an invasion of Japan. It argued that the blockade was working well, cutting off nearly all oil, food and troop movements to and from Japan. It expected that the blockade would eventually lead to surrender. Civilians overruled them.

In July 1945 the AAF saw its doctrine of strategic bombing working as intended. The original plan was to have used B-29 bombers, from high altitude, with greater precision than the B-17 and B-24 bombers used in Europe. Unexpected high-altitude winds proved this was impossible, and Gen. Curtis LeMay, newly commanding the strategic bombers, on his own authority changed to low-altitude incendiary bombing. He shed the machine guns and gunners, and the gasoline no longer needed to lift the planes to 30,000 feet. The result was a doubling of the bomb load, and very scared fliers who were greatly relieved to discover their losses were less using the new tactics. From the first raid on March 9, the new tactic was devastating. working to perfection. The B-29 dropping conventional high explosives and incendiaries was the perfect instrument to destroy the infrastructure of Japan's larger cities. The great bombing campaign had just started; it was planned to peak a year later. The atomic bomb was not part of AAF doctrine; the AAF generals had not been consulted, knew very little about the bomb and even demanded a direct order from President Truman before they agreed to explode it.

The Army agreed that the combination of blockade and strategic bombing would eventually destroy every Japanese city, but felt it could not destroy the Japanese Army, which was widely dispersed and dug in.

General Marshall worried that the American people might grow weary of more years of warfare, and might even demand some sort of compromise peace in order to bring the soldiers home. (Marshall underestimated the intense determination of nearly all Americans to destroy Japan.) Furthermore he objected to dropping the bombs on cities on moral and political grounds (Japan might become an enemy forever). Most of all, he had a tactical rather than strategic use in mind. Only a handful of bombs were being built, (two to four per month) and MacArthur's invasion forces ought to have all of them. Nine bombs had been allocated to "Operation Olympic". Marshall and his planners concluded that Japan would surrender only after ground troops captured Tokyo. The invasion of Kyushu was scheduled November 1; all bombs available then (probably seven) should be used there. They would give invading infantry forces enough firepower to destroy defensive ground installations, communications facilities, kill exposed enemy soldiers, and also block the arrival of reinforcements. To waste the precious bombs on irrelevant civilians would cause more American casualties, and like all the high American officials Marshall was committed to minimizing American--not Japanese-- losses.

Manhattan Project

President Harry S. Truman, who had been completely frozen out of decision making and secret information before he suddenly became President in April, did not know what he wanted to do. He lurched this way then that, depending on who talked to him last. The man who talked to him last about the bomb was Henry Stimson. Stimson rarely participated in strategic planning, but he had one card up his sleeve--the atomic bomb. To build it, Roosevelt, set up the Manhattan Project.

The Manhattan Project was managed by Major General Leslie Groves (Corps of Engineers) with a staff of reservists and many thousands of civilian scientists and engineers. Nominally Groves reported directly to Marshall, but in fact Stimson was in charge. Stimson secured the necessary money and approval from Roosevelt and from Congress, and made sure Manhattan had the highest priorities. He controlled all planning for the use of the bomb, overruling the high command of the Army, Navy and AAF in the process. He wanted "Little Boy" (the Hiroshima bomb) dropped within hours of its earliest possible availability. And it was. Stimson wanted Japan to surrender, and thought the Hiroshima bomb on August 6 would provide the final push Tokyo needed. When nothing seemed to happen he had Truman drop "Fat Man" on Nagasaki on August 9. The Japanese offered to surrender on August 10.

Stimson's vision

In retrospect it seems likely that the impact of continued blockade, relentless bombing, and the Russian invasion of Manchuria would have somehow forced the Japanese Army to surrender sometime in late 1945 or early 1946 even without the atomic bombs (though not without very large numbers of Japanese casualties.) But Stimson saw well beyond the immediate end of the war. He was the only top government official who tried to predict the meaning of the atomic age--he envisioned a new era in human affairs. For a half century he had worked to inject order, science, and moralism into matters of law, of state, and of diplomacy. His views had seemed outdated in the age of total warfare, but now he held what he called "the royal straight flush." The impact of the atom, he foresaw, would go far beyond military concerns to encompass diplomacy and world affairs, as well as business, economics and science. Above all, said Stimson, this "most terrible weapon ever known in human history" opened up "the opportunity to bring the world into a pattern in which the peace of the world and our civilization can be saved." That is, the very destructiveness of the new weaponry would shatter the ages-old belief that wars could be advantageous. It might now be possible to call a halt to the use of destruction as a ready solution to human conflicts. Indeed, society's new control over the most elemental forces of nature finally "caps the climax of the race between man's growing technical power for destructiveness and his psychological power of self-control and group control--his moral power."

In 1931, when Japan invaded Manchuria Stimson, then Secretary of State, proclaimed the famous "Stimson Doctrine." It said no fruits of illegal aggression would ever be recognized by the United States. Japan just laughed. Now the wheels of justice had turned and the "peace-loving" nations (as Stimson called them) had the chance to punish Japan's misdeeds in a manner that would warn aggressor nations never again to invade their neighbors. To validate the new moral order, the atomic bomb had to be used against civilians. Indeed, the Japanese people since 1945 have been intensely anti-militaristic, pointing with anguish to their experience at Hiroshima and Nagasaki. Was Stimson then guilty of a crime (as many Japanese now believe)? Perhaps, but it has to be recognized that he moved the issue to a higher plane than one of military ethics. The question was not one of whether soldiers should use this weapon or not. Involved was the simple issue of ending a horrible war, and the more subtle and more important question of the possibility of genuine peace among nations. Stimson's decision involved the fate of mankind, and he posed the problem to the world in such clear and articulate fashion that there was near unanimous agreement mankind had to find a way so that atomic weapons would never be used again. Thanks in great part to Stimson's vision, they never have been used since August of 1945.

Impact on Japan

The Strategic Bombing Survey did confirm that the weapons had a major psychological effect on the populace:

Prior to the dropping of the atomic bombs, the people of the two cities had fewer misgivings about the war than people in other cities and their morale held up after it better than might have been expected. Twenty-nine percent of the survivors interrogated indicated that after the atomic bomb was dropped they were convinced that victory for Japan was impossible. Twenty-four percent stated that because of the bomb they felt personally unable to carry on with the war. Some 40 percent testified to various degrees of defeatism. A greater number (24 percent) expressed themselves as being impressed with the power and scientific skill which underlay the discovery and production of the atomic bomb than expressed anger at its use (20 percent).

Popular opinion was simply not of concern to the deadlocked Imperial Cabinet. Only the unprecedented intervention by the Emperor broke the tie in the direction of the peace faction. The U.S. accepted less than the unconditional surrender it had been demanding, not having known that the chief argument of the hard-liners was the continuation of the monarchy, the one condition on which the Japanese insisted.

Ethics debate on Strategic Bombing

During the war prewar pacifists and a few churchmen (especially Catholics troubled over the bombing of Catholic cities like Rome and Cologne) began to question the morality of bombing cities. After Hiroshima the issue focused on the atomic bomb, with much of the discussion echoing the fears of the interwar period about flotillas of enemy bombers dropping poison gas on New York City. This time the technology was capable of mass destruction; everyone had genuine fears of a nuclear war that would kill tens of millions of Americans within minutes. Only the United States had ever used atomic weapons--and in both cases the victims were civilian populations of another race. Many of the top soldiers thought the atomic bomb was unnecessary--that their particular strategy would have won the war eventually. Each of the alternative strategies, however (such as the Army invasion of Kyushu and Honshu, the Navy's tight blockade, the Air Force's relentless firebombing) would have produced more American casualties--and probably far more Japanese killed. Some historians, starting form the assumption that the bomb was "unnecessary" have speculated that it must therefore have been used for some motivation other than military victory. Perhaps the bureaucratic dynamics of the Manhattan Project were such that the bomb had to be dropped to prove the expenditures on it were not wasted? This was highly unlikely, since Truman would not have been blamed for expenditures that took place before he took charge. Other historians suggest that the bomb was dropped in order to influence or frighten the Russians, or perhaps to keep them out of the war. In fact the Pentagon, the State Department and the White House had been begging the Russians to enter the war, and at no time did Truman ever suggest to Stalin that in fact his entry into the Pacific war was unnecessary or unwanted. As for frightening the Russians, that seems unlikely too. Truman and Stimson knew that Russia had the capability of building their own bomb; unleashing the American weapon was less likely to frighten the dedicated Communists than to divert them from peaceful recovery into a new arms race.

Was it necessary? Did unleashing the nuclear genie doom the human race to the risk of eventual annihilation? Were Americans so fascinated with technology that they had lost sight of the moral dimensions of their behavior? Were the American conventional bombing campaigns against cities inherently immoral?