Updated 6 August 2010

Lyrics from 'Enola Gay', Orchestral Manoeuvres in the Dark

On 6 August, 1945, the first Atomic Bomb to be used against an enemy was released by the US B29 bomber, Enola Gay, to explode above the city of Hiroshima, Japan. What follows is the build up to why the bomb was made and subsequently dropped, together with the repercussions of dropping the bomb.

Why Build the Bomb?

The atomic bomb was built initially as a response to Germany having discovered how to split (fission) the uranium atom, thus releasing the energy inside the nucleus. It was thought that Hitler wanted to build an atomic bomb. Two refugees from the Nazi regime, Leo Szilard, a physicist, and Eurene Wigner, both from Hungary, were so convinced that this would happen, they began to search for a way to get a message to Western governments.

The Intervention of Einstein

Albert Einstein
Old Grove Rd.
Nassau Point
Peconic, Long Island

August 2, 1939

F.D. Roosevelt
President of the United States
White House
Washington DC

Sir:

Some recent work by E Fermi and L Szilard, which has been communicated to me in manuscript, leads me to expect that the element uranium may be turned into a new and important source of energy in the immediate future. Certain aspects of the situation which has arisen seem to call for watchfulness and, if necessary, quick action on the part of the Administration. I believe therefore that it is my duty to bring to your attention the following facts and recommendations:

In the course of the last four months it has been made probable through the work of Joliot in France as well as Fermi and Szilard in America - that it may become possible to set up a nuclear chain reaction in a large mass of uranium, by which vast amounts of power and large quantities of new radium-like elements would be generated. Now it appears almost certain that this could be achieved in the immediate future.

This new phenomenon would also lead to the construction of bombs, and it is conceivable - though much less certain - that extremely powerful bombs of a new type may thus be constructed. A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port together with some of the surrounding territory. However, such bombs might very well prove to be too heavy for transportation by air.

The United States has only very poor ores of uranium in moderate quantities. There is some good ore in Canada and the former Czechoslovakia, while the most important source of uranium is Belgian Congo. In view of the situation you may think it desirable to have more permanent contact maintained between the Administration and the group of physicists working on chain reactions in America. One possible way of achieving this might be for you to entrust with this task a person who has your confidence and who could perhaps serve in an unofficial capacity. His task might comprise the following:

1. to approach Government Departments, keep them informed of the further development, and put forward recommendations for Government action, particular attention to the problem of securing a supply of uranium ore for the United States;
2. to speed up the experimental work, which is at present being carried on within the limits of the budgets of university laboratories, by providing funds, if such funds be required, through his contacts with private persons who are willing to make contributions for this cause, perhaps also by obtaining the co-operation of industrial laboratories which have the necessary equipment.

I understand that Germany has actually stopped the sale of uranium from the Czechoslovakian mines which she has taken over. That she should have taken such early action might perhaps be understood on the ground that the son of the German Under-Secretary of State, von Weizsäcker, is attached to the Kaiser-Wilhelm-Institut in Berlin where some of the American work on uranium is now being repeated.

Yours very truly,

Albert Einstein

The letter above was written by Einstein after he was sought out by Szilard and Wigner. Einstein was himself a refugee from Nazi Germany due to his Jewish faith. The letter was received by President Roosevelt in October 1939, two months after the letter was written. Slowly, the United States began to collate information on how to build an atomic bomb in order to defend their borders should Germany succeed in building a bomb of its own.

The Threat

In 1941, Great Britain began an independent study as to the feasibility of an atomic bomb and gave their support to The United States once Britain concluded that an atomic bomb could, indeed, be made. Reports were coming through from Germany that their scientists were pushing ahead with their own bomb project, forcing the United States to push forward strongly with the atomic bomb programme.

Battle of the Telemark

Germany did in fact make a half-decent attempt to build a prototype atomic bomb, but they were stopped through the sheer determination of a small group of men from the Norwegian Resistance and 40 service personnel from the British Forces, who crossed a great distance on skis to destroy the German heavy water production plant¹. Heavy water is used as a moderator in nuclear reactors, and would have been vital to the creation of the first atomic bomb.

Unfortunately, 30 of the British servicemen died when the planes they were travelling in crashed. The ten remaining survivors were captured by the Germans and executed.

It was ironic that in June, 1942, Germany thought the huge investment needed to build an atomic bomb was far too large for their war economy to sustain. The German arrogance that they would win the war without the bomb was also a factor in their decision-making. The Allies were unaware of Germany's decision.

The Manhattan Project

Also in June, 1942, the US atomic bomb project was moved to the War Department's Army Corps of Engineers. A Manhattan Engineer District was created by the Corps to disguise the project, with its headquarters based, initially, in New York City. The Manhattan Project, as it came to be known, employed nearly 129,000 people. The throng of personnel were needed to build, run and maintain the huge industrial facilities that were needed to separate uranium and plutonium needed to create an atomic bomb.

In 1942, the Los Alamos Laboratory facility began to be built. Based on a remote site in New Mexico, many project scientists could work together in complete secrecy. The laboratory opened in April 1943 where personnel began to design two different kinds of bomb: one using uranium, the other plutonium (the most difficult of challenges).

The cost of building the bombs was immense². Only the threat of Germany and Japan drove them forward to carry on with the project.

At no time, from 1941 to 1945 did I ever hear it suggested by the President, or any other responsible member of the government, that atomic energy should not be used in the war.

Henry Stimson, Secretary of War (1940 - 1945)

If this weapon fizzles, each of you can look forward to a lifetime of testifying before congressional investigating committees.

General Groves to his staff, 24 December, 1944.

The Birth of the Bombs

The Manhattan Project was a success. Two bombs were built: the 'Little Boy' and the 'Fat Man'. The Little Boy triggered an explosion by firing one piece of uranium 235 into another. The Fat Man contained a sphere of plutonium 239 which was surrounded by blocks of high explosives. The design of this bomb was to produce a symmetrical implosion which would critically compress the plutonium to set off the nuclear reaction.

On 12 April, 1945, President Roosevelt died. Vice-President Harry S Truman had been in office less than three months, but he was sworn in on the same day that Roosevelt died. Roosevelt had not told Truman about the bomb, or the Manhattan Project. He entered office without the knowledge that was necessary in order for him to make correct assumptions and decisions. Hence, Truman was left with the legacy of the atomic bomb: should it be used in an act of war or not? The road ahead was far from clear to Truman. Japan had been weakened, but was still not willing to surrender. The bombs seemed the most correct course of action, although a bloody invasion would be required if the bombs did not force Japan to surrender.

The week before Roosevelt died, the Japanese Prime Minister and his Cabinet resigned - this was the second time this had happened in less than a year. The course of the war was disastrous for the Japanese. Within the government, some realised that a way had to be found to end the war. An 'unconditional surrender' was in no way possible. As a way to begin negotiations, Japan approached the Soviet Union. The hope was that, under Stalin, a way could be found to negotiate a conditional surrender with the Allies.

Spying on the Japanese

Japan was unaware that, back in 1940, American intelligence had cracked the Japanese diplomatic code. In the spring of 1945, the United States gained knowledge that Japan was willing to negotiate peace, but that an unconditional surrender would not be tolerated. This was good news to the Allies until further intelligence revealed that Japan had begun to build up forces in the south of the country. This was precisely where American forces were scheduled to invade later on in the year. However, it also indicated to the US that Japan was preparing to fight to the bitter end.

The Soviet Union

An alliance between the United States, the British Commonwealth and the Soviet Union only came about after Germany advanced against Russia in 1941. Both sides were still suspicious of each other. The United States and British Commonwealth were tense over the Soviet influence over Eastern European countries after Germany was defeated and it was thought that the use of the atomic bomb would help keep the Soviet Union in check.

The Soviet Union and Japan were at peace with each other, but the United States approached the Soviet Union to join in the Pacific war. The US was worried that Japan would be able to mobilise its forces in China in defence of its homeland. The thought was that bringing in the Soviet Union would help tip the war in favour of the Allies. In spring 1945, the blockade of Japan was nearly complete, thus making troop movements between China and Japan more difficult. Advisers to President Truman were worried that Communism would spread to Asia. Their concerns were well founded as it was Stalin's intention to bring China and Korea within the Soviet Union, but also to share in the occupation of Japan.

Although the Manhattan Project was dominated by American personnel and money, Great Britain and Canada were also involved. Churchill and Roosevelt concealed the project from Stalin in the hope of delaying the Soviet's entrance into the world of nuclear weapons production. It was Soviet spies who managed to send information back to the Soviet Union, but it would be America's use of the bomb that forced Stalin's hand into their own atomic research and the production of their own bombs.

Choosing the Targets

Military deployment of the atomic bomb was being prepared while plans to invade Japan by sea and air were also being set in motion. Recommendations were made for which areas to target. General Groves, who was in charge of the Manhattan Project, wanted to show the Japanese the full might of the bomb to force them into surrender. Accuracy was of paramount importance. Errors would not show the full effect and would reduce the shock to the Japanese. Suhbsequently, it was decided it was best to drop the bomb during daylight hours and while weather was clear. The targets were chosen: Kyoto, Hiroshima, Kokura and Niigata. Orders were given to the Air Forces not to firebomb these cities during fly-overs. This would show the full force of the bombs, but also lull the Japanese into not worrying about planes that were flying over.

Stimson, Secretary of War, stopped Kyoto being bombed. Having visited the city several times, he said it was too much of an ancient culture and of too much of historical importance to bomb. Kyoto was removed from the list and, in its place, Nagasaki was added.

Should the Japanese be warned?

Another group had been formed during the process of building the atomic bomb: The Interim Committee on Post-war Atomic Policy. On 31 May, 1945, Secretary Stimson chaired a meeting. A discussion took place on whether to warn Japan of the forthcoming event and which targets had been chosen. It was decided not to warn them, in case they might try to shoot down the planes or place prisoners of war within the cities. Another idea was to explode the bomb high over Tokyo Bay at night. This would have taken the Japanese leaders by surprise: still, they did not know how powerful the bomb was and a non-lethal demonstration may have been impossible. There was also the risk that it might not impress the Japanese sufficiently to force surrender.

Invasion Plans

President Truman gave preliminary approval to the invasion plans on 18 June, 1945. The plans were presented by General Marshall and given the name Operation Downfall, comprising two sections. 767,000 Marines and Army troops would begin the invasion on 1 November, 1945 and would have the code name Operation Olympic. This force would then occupy the southern part of Kyushu to gain the use of its airbase and staging area for the second force. Operation Coronet would be the second invasion group and its orders were to occupy the capital, Tokyo, and enough of Honshu to force Japan to surrender. Knowing that potentially one million American casualties could have resulted from a process of occupation, Truman decided that the bomb would have to be used.

A conference to discuss a peace settlement in Europe was due to take place outside Berlin in mid-July, 1945. The conference³ was also to issue a surrender ultimatum to Japan. President Truman used his ingenuity and delayed the conference. At Potsdam, he gave final approval for the atomic bomb to be dropped if Japan rejected the surrender terms.

In a New Mexico desert at 5:29:35 am on 16 July, 1945, a blinding flash and searing heat marked the beginning of the nuclear age. The explosion was equal to the effects of 20,000 tons of TNT. The first bomb had a code name of Trinity and was a huge success. Far beyond what anyone had envisaged.

On 26 July, 1945, the United States, Britain, and China issued the Potsdam Declaration, which demanded the surrender of Japan immediately or the nation would face 'prompt and utter destruction.' Allied and domestic opposition would accept nothing but 'unconditional surrender' and the declaration contained no reference to keeping Emperor Hirohito on the throne. Neither, for reasons of military secrecy, did it contain any direct reference to the atomic bomb or the Soviet Union's eagerness to enter into the war. The Japanese government did not change its mind and so on 28 July Prime Minister Suzuki prepared a statement announcing that his government would not agree to the Declaration.

Below is a letter written by Harry Truman to Professor James L Cate written on 12 January, 1953. This letter presents Truman's understanding of the inevitability of using the atomic bombs to end World War II.

THE WHITE HOUSE

Washington

January 12, 1953

Dear Professor Cate;

Your letter of 6 December, 1952 has just been delivered to me. When the message came to Potsdam that a successful atomic explosion had taken place in New Mexico, there was much excitement and conversation about the effect on the war then in progress with Japan. The next day I told the Prime Minister of Great Britain and Generalissimo Stalin that the explosion had been a success. The British Prime Minister understood and appreciated what I'd told him. Premier Stalin smiled and thanked me for reporting the explosion to him, but I'm sure he did not understand its significance. I called a meeting of the Secretary of State, Mr Byrnes, the Secretary of War, Mr Stimson, Admiral Leahy, General Marshall, General Eisenhower, Admiral King and some others, to discuss what should be done with this awful weapon.

I asked General Marshall what it would cost in lives to land on the Tokyo plain and other places in Japan. It was his opinion that such an invasion would cost at a minimum one quarter of a million casualties, and might cost as much as a million on the American side alone, with an equal number of the enemy. The other military and naval men present agreed. I asked Secretary Stimson which sites in Japan were devoted to war production. He promptly named Hiroshima and Nagasaki, among others. We sent an ultimatum to Japan. It was rejected.

I ordered atomic bombs dropped on the two cities named on the way back from Potsdam, when we were in the middle of the Atlantic Ocean. In your letter, you raise the fact that the directive to General Spaatz to prepare for delivering the bomb is dated 25 July. It was, of course, necessary to set the military wheels in motion, as these orders did, but the final decision was in my hands, and was not made until we were returning from Potsdam. Dropping the bombs ended the war, saved lives, and gave the free nations a chance to face the facts. When it looked as if Japan would quit, Russia hurried into the fray less than a week before the surrender, so as to be in at the settlement. No military contribution was made by the Russians toward victory over Japan. Prisoners were surrendered and Manchuria occupied by the Soviets, as was Korea, North of the 38th parallel.

Sincerely,

The letter was signed by Harry Truman

The Plane is Readied

The Enola Gay was a B-29 Superfortress bomber. Being the most complicated and expensive weapon produced by the United States, it brought fortunes to those towns and cities involved with the building of the B-29. Nearly 4,000 were built for combat during World War II.

General Paul W Tibbets, Jr named the plane Enola Gay after his mother.

The Crew of Enola Gay

The orders came through on 5 August, 1945. Conditions were good and the next day would be when the bomb was dropped. To eliminate the risk of the bomb exploding if the Enola Gay crashed, the bomb would be assembled during the flight. The bomb was loaded into the Enola Gay later that day. 'Little Boy' was 12 feet long and 28 inches in diameter. They had never seen a bomb so big, weighing in at 9,000 pounds. That night, the crew were told for the first time exactly what the weapon entailed.

At approximately 2am on the morning of 6 August, the Enola Gay started on the long flight from Tinian. Two observation planes carrying cameras and scientific instruments followed.

The trip to Japan was uneventful. At about 7am, the Japanese radar net detected the aircraft heading toward Japan, and broadcast the alert throughout the area. Soon afterward, an American weather plane passed over Hiroshima, but no-one intercepted it and it appeared that the people below had begun their daily work thinking that any danger had passed.

At 7.25am, the Enola Gay, at 26,000 feet, was cruising over its target. At 8am the Japanese again detected two B-29s heading toward Hiroshima. Radio stations quickly sent out broadcasts warning people to take shelter as quickly as possible, but the advice was unheeded and it was doubtful that taking shelter would have saved lives⁴. At 8.09am, the crew of the Enola Gay had a clear vision of the city below. A message was received indicating that weather was good.

The bomb was released at 8.16am.

The Devastation

Hiroshima was destroyed. Two thirds of the buildings in the city were demolished. Fires raged throughout. An area of approximately 4.4 miles in diameter around where the bomb blew was now obliterated. Even those buildings that weren't, suffered major structural damage or were on fire. The bomb exploded in the air at 1,890 feet.

Areas further away from the explosion soon became contaminated. Half an hour after the explosion, black dirty rain brought down radioactive dirt and dust, ruining the water supply. The rain lasted for many days.

Communications into the city were down. The Japanese leaders were confused by what had happened. They knew that there hadn't been a major strike on the city, as they would have detected the huge number of planes needed to have caused the amount of devastation that was being reported.

A Japanese pilot was instructed to fly to Hiroshima and report back on what had taken place. The pilot took off and, still over 100 miles away from Hiroshima, he saw a huge cloud of smoke high in the sky. When he reached Hiroshima, he knew that total devastation had taken place. He reported back what he saw, landed his plane, then began to organise relief measures.

The reports coming back to military headquarters shocked them. They realised what had happened: the Americans had dropped an atomic bomb. Their intelligence had been wrong. Japan had thought the Americans' progress was still in the scientific stage.

16 hours after the bomb had been dropped, President Truman made a public announcement.

Sixteen hours ago an American airplane dropped one bomb on Hiroshima. It is an atomic bomb. We are now prepared to obliterate more rapidly and completely every productive enterprise the Japanese have above ground in any city. If they do not now accept our terms they may expect a rain of ruin from the air the like of which has never been seen on this earth.

Two days after the Americans bombed Hiroshima - 8 August, 1945 - the Soviet Union joined in the Pacific war and declared war on Japan. America was disappointed by this as they’d hoped to end the war in the Pacific before Russia joined in.

Nagasaki

The orignal target had been Kokura. Its population was spared only after the bomber had made three failed bomb-runs on the city. Nagasaki was the secondary target. The pilot made the decision to bomb the secondary target instead as there was less cloud cover.

It took the dropping of 'Fat Boy' on Nagasaki on 9 August, 1945, for Japan to surrender. The bomb was of a different make to the first dropped on Hiroshima, but the devastation was just as horrific.

Life Begins to Return

The first life to come back to Hiroshima were weeds. A plant known as horseweed took hold. The citizens of Hiroshima were so close to starvation they cut them down to eat them. They drank rainwater captured in whatever they could use. They didn't realise the rain and food were contaminated and they were poisoning themselves further.

It is thought that up to 200,000 people died due to the direct force of the bomb and the radiation that stayed within the area afterwards. No other bomb at that time was capable of producing such a high death toll.

The injuries suffered by the inhabitants of Hiroshima were severe. An eyewitness account can be found at The Atomic Bombing of Hiroshima by Father P Siemes but please be warned that what Father Siemes describes is horrific.

Hiroshima Today

With a population of 1.12 million, Hiroshima is a thriving and bustling city. It has shopping centres and malls that rival Tokyo for their range in merchandise.

Mazda was founded within the city as were many other major industries. Quite interestingly, one quarter of Hiroshima's electricity use comes from nuclear power.

Every year on 6 August the people of Hiroshima hold a ceremony in Peace Memorial Park. The mayor of the City reads his Peace Declaration. They strive to rid the world of nuclear weapons and Hiroshima calls itself an international peace culture city.

The Enola Gay can be seen at the National Space and Air Museum in Washington DC, United States of America