The First War of Physics (48 page)

But how much time, and at what cost in human lives? Japan’s willingness to surrender was actually highly debatable. The US Army Signals Intelligence Service had towards the end of 1940 managed to build a replica of the PURPLE cipher machine used by the Japanese to encipher their diplomatic messages. Truman was receiving daily summaries of the contents of radio communications between Tokyo and its embassies. This deciphered message traffic, codenamed ‘Magic’, gave the Allies a window on the drama unfolding in Tokyo.

The Magic intelligence revealed that attempts to seek a negotiated peace by Japanese diplomats in Europe were being conducted without authority from Tokyo. The only authorised diplomatic effort was that of ambassador Naotake Sato in Moscow, who had been charged initially with the task of improving Soviet–Japanese relations. A meeting with Molotov on 11 July had produced no result. According to Sato, Molotov was non-committal on his proposals.

Foreign Minister Shigenori Togo had not yet received Sato’s report of his meeting with Molotov when on 12 July he sent a message recommending that Sato take a further step, informing the Soviets of the ‘Imperial Will’ to see an end to the war. In essence, Togo now sought help from the Soviet Union to broker an end to the war on terms that would be acceptable to the Japanese. But his message betrayed little room for compromise:

His Majesty the Emperor, mindful of the fact that the present war daily brings greater evil and sacrifice upon the peoples of all belligerent powers, desires from his heart that it may be quickly terminated. But so long as England and the United States insist upon unconditional surrender the Japanese Empire has no alternative but to fight on with all its strength for the honour and the existence of the motherland.

On 18 July Sato argued in his reply to Togo that an unconditional surrender, or something very close to this, was all Japan could hope for. In a further message dated 20 July he suggested that an unconditional surrender in which Japan’s imperial institutions were allowed to continue might be acceptable to the Allies. He argued that while loyalty to the obligations of honour was good, it was surely meaningless to prove such devotion by wrecking the state.

In his reply on 21 July, Togo was emphatic:

With regard to unconditional surrender (I have been informed of your 18 July message) we are unable to consent to it under any circumstances whatever. Even if the war drags on and it becomes clear that it will take much more bloodshed, the whole country as one man will pit itself against the enemy in accordance with the Imperial Will so long as the enemy demands unconditional surrender. It is in order to avoid such a state of affairs that we are seeking a peace which is not so-called unconditional surrender through the good offices of Russia.

Togo’s vision of the whole country rising as one against the enemy was a central plank of
Ketsu Go
, a military strategy designed to weaken American
resolve by inflicting enormous losses during the initial stages of the threatened invasion of Japan’s home islands. In preparation, Japan had built up its homeland defences, planned for ‘special attack’ or suicide missions against invading forces, and formed a National Resistance Programme, consisting of all able-bodied citizens, male and female, armed with bamboo spears.

Operation Downfall, the planned invasion of Japan, was scheduled to begin with Operation Olympic, the invasion of Kyushu, southernmost of Japan’s home islands, on 1 November 1945. After its capture, Kyushu would provide the air and naval bases for the launch of Operation Coronet, the capture of Tokyo itself, tentatively scheduled for 1 March 1946. In the planning of Operation Olympic, it had been assumed that the Japanese would be able to muster no more than six divisions on Kyushu, with just half of these confronting the American invasion forces, and between 2,500 and 3,000 aircraft. Intercepted military (as opposed to diplomatic) radio messages now revealed the massing of considerably greater Japanese forces on Kyushu, completely undermining the assumptions on which Olympic was based.

Estimates of American casualties varied greatly, but the battle for Okinawa had left 12,500 Americans killed or missing and an estimated 100,000 Japanese dead. Nobody was under any illusions that a high price would have to be paid for the conquest of Japan.

Stimson nevertheless believed that the Japanese were susceptible to reason. Roosevelt had set the unconditional surrender of Japanese forces as a national war aim in 1943. Stimson had earlier argued for a softening of the American position through the offer of concessions regarding the Emperor and his imperial institutions which he characterised as ‘the equivalent of an unconditional surrender’. This, he believed, could make all the difference between Japan’s acceptance or rejection of the ultimatum now being drafted in Potsdam. At issue, however, was the very use of the word ‘unconditional’. The 22 July Diplomatic Summary of the Magic intelligence had revealed that if this word was to be used in any final ultimatum, then Togo had already rejected it.

What further complicated matters was the Soviet Union. Despite the representations now being received from Sato, Stalin had agreed to Truman’s request to declare war on Japan by 15 August. This was a move that in itself would certainly end the war, most probably with the unconditional surrender of Japan, but at the same time would give the Soviets licence to make more territorial gains in the Pacific region.

There was another way, Byrnes argued. The atomic bomb offered a way to end the war against Japan before the Soviets could get involved. American lives could be saved, a war that had dragged on far too long could finally be ended, Soviet aspirations could be thwarted and American superiority in military technology could be unequivocally demonstrated, thereby establishing a strong position in the post-war world. There was a further consideration. To spend $2 billion developing a weapon that would never be used was simply unprecedented in the history of warfare.

For Truman and Byrnes, this was an easy decision. On 25 July, Truman wrote in his diary:

This weapon is to be used against Japan between now and August 10th. I have told the Sec. of War, Mr Stimson to use it so that military objectives and soldiers and sailors are the target and not women and children. Even if the Japs are savages, ruthless, merciless and fanatic, we as the leader of the world for the common welfare cannot drop this terrible bomb on the old Capitol or the new.

He and I are in accord. The target will be a purely military one and we will issue a warning statement asking the Japs to surrender and save lives. I’m sure they will not do that, but we will have given them the chance. It is certainly a good thing for the world that Hitler’s crowd or Stalin’s did not discover this atomic bomb. It seems to be the most terrible thing ever discovered, but it can be made the most useful.

Stimson was a tired insomniac. Truman and Byrnes, confident that they now had a weapon that would be decisive, were not interested in concessions. On 26 July, as Little Boy was being unloaded on Tinian, Truman,
Churchill
²
and the Chinese leader Chiang Kai-Shek released the Potsdam Declaration to the waiting press. The Allied position remained firm:

We call upon the government of Japan to proclaim now the unconditional surrender of all Japanese armed forces and to provide proper and adequate assurances of their good faith in such action. The alternative for Japan is prompt and utter destruction.

There were no concessions.

Japan was not at war with the Soviet Union and Stalin was not a signatory to the declaration. Togo reasoned that it might yet be possible to get better terms through his diplomatic channels to Moscow. He appears to have been unaware that Soviet forces were already massing on the border of Japanese-occupied Manchuria, preparing for invasion.

The Supreme Council for the Direction of the War met the next day to discuss the declaration. These were the so-called ‘Big Six’ – Prime Minister Kantaro Suzuki, Army Minister Korechika Anami, Navy Minister Mitsumasa Yonai, General Yoshijiro Umezu and Admiral Soemu Toyoda, the Chiefs of Staff of the Imperial Army and Navy, and Foreign Minister Togo. Unsurprisingly, the militarists Anami and Umezu advocated outright rejection. Togo argued that they should instead seek to buy some time, wait until Stalin had returned to Moscow from Potsdam, and press for a mediated peace on better terms.

The outcome of the ensuing debate was, perhaps, predictable. Suzuki delivered the Japanese response the next day, 28 July, during a press conference at his official residence in Tokyo. When asked by journalists for his view regarding the Potsdam Declaration, he claimed that his government found no value in it. He said that there was no other recourse but to
mokusatsu
the declaration, variously interpreted as ‘ignore’, ‘withhold comment’, or ‘treat with silent contempt’. The Japanese would ‘resolutely fight for the successful conclusion of this war’.

For the Allies, there was no ambiguity in Suzuki’s reply. The die was now cast.

Petitions to the President

Szilard had not been invited to the Trinity test, and was not even aware that it was taking place. On 16 July has was busy redrafting his petition to the President. As before, the purpose of the new petition was not necessarily to try to change any decisions that had already been made. Its purpose was rather to record the dissent among the community of physicists that had helped to build the bomb. The petition acknowledged the realities of the situation but urged that Japan be given the opportunity to surrender:

The war has to be brought speedily to a successful conclusion and attacks by atomic bombs may very well be an effective method of warfare. We feel, however, that such attacks on Japan could not be justified, at least not until the terms which will be imposed after the war on Japan were made public in detail and Japan were given an opportunity to surrender.

If such public announcement gave assurance to the Japanese that they could look forward to a life devoted to peaceful pursuit in their homeland and if Japan still refused to surrender, our action might then, in certain circumstances, find itself forced to resort to the use of atomic bombs. Such a step, however, ought not to be made at any time without seriously considering the moral responsibilities which are involved.

Neither the 3 July nor 17 July petitions referred to a demonstration of the bomb as part of an ultimatum to the Japanese. Rather, the petitions sought to appeal to Truman’s sense of moral responsibility. The decision to use atomic bombs against Japan would usher in a new era of warfare based on
weapons of mass destruction. It was within the gift of the President of the United States – singled out by virtue of America’s lead in atomic power – to prevent this from happening.

The 17 July petition attracted 68 signatures and was passed to Compton on 19 July. Compton checked first with Groves before passing it on to Nichols on 24 July. It was couriered to Groves the next day. Groves then sat on it until 1 August, when he forwarded it to Stimson’s office. But Stimson was still in Potsdam, and he would not see the petition until he returned.

The wheels were already spinning. In the Potsdam Declaration, the demand for unconditional surrender was clear enough, though there was no clarity on the terms to be imposed on Japan after the surrender. The Allies threatened ‘prompt and utter destruction’, but there was no clarity on how this might be achieved.

There is no telling what the Big Six would have decided if, as Stimson had suggested, the ‘equivalent’ of unconditional surrender had been demanded without use of the actual words and if, as the physicists had urged, the terms to be imposed on Japan and the means of destruction had been made clear. However, the interpretation of subsequent events suggests that even these efforts would not have been enough to avert the catastrophe that now loomed.

The moment has arrived

The team of physicists on Tinian had all but prepared Little Boy for battle by 31 July. The final arming of the bomb would be completed by Parsons on board the B-29 that would deliver the weapon to its target. On the same day, three B-29s of the 509th Composite Group completed a final training mission to Iwo Jima, and practised the manoeuvre that Tibbets had worked out. The mission was successful. Everything was ready.

Only the weather forecast prevented the first atomic bomb from being dropped on 1 August. On 2 August, three B-29s delivered the components of a second, Fat Man, bomb to Tinian. Tibbets and his crews monitored the weather forecasts as the tension grew.

At 3:00pm on 4 August, Tibbets called a briefing for the crews of the seven B-29s that would be involved in the first atomic bombing mission. Three planes would fly about an hour ahead to determine the weather conditions and level of cloud cover over the various target choices. The B-29 carrying Little Boy would be flown by Tibbets himself, accompanied by two planes to observe and photograph the mission. The seventh B-29 would remain on the ground on Tinian as a contingency in the event that Tibbets’ plane ran into problems.

The crews assembling for the briefing were surprised to find the combat room guarded by military police. Tibbets stood on the platform in front of two blackboards – both covered – and a projector screen. ‘The moment has arrived’, he said. ‘This is what we have all been working towards. Very recently the weapon we are about to deliver was successfully tested in the States. We have received orders to drop it on the enemy.’ The blackboards were uncovered. They bore maps of three Japanese cities, Hiroshima, Kokura and Nagasaki, in order of priority.
³
Forecasts predicted a break in the weather over southern Japan within the next few days, and the attack had been set provisionally for the morning of 6 August.

Tibbets then introduced Parsons, who proceeded to explain that the new weapon was unprecedented in the history of warfare. ‘It is the most destructive weapon ever produced. We think it will knock out everything within a three-mile area.’ It would deliver the kind of devastation that would typically require
2,000
fully loaded B-29s. Parsons now had everybody’s attention. He described the Trinity test, which he had witnessed from a B-29, flying overhead, but was unable to show film of the test because the projector malfunctioned. His descriptions were enough, however. He handed out welder’s goggles, and explained that the blast was expected to be brighter than the sun and might blind anyone looking directly at it.