released 01 jun 09 / last mod 01 jun 09 / greg goebel / public domain
* The war against Europe ended before the US atomic bomb could be tested, but the war against Japan continued. The Americans detonated the first atomic bomb in July 1945, and in the next month dropped two atomic bombs on Japan, with the war in the Pacific ending soon after. The use of the bombs on Japan began a new age of nuclear tensions.
* While the USAAF was working on delivering the atomic bomb, Los Alamos pushed forward on putting it together. Although implosion looked and was difficult, progress was made on getting it to work. X-ray imaging was used to observe the detonation of small spherical assemblies of explosives in order to back up theoretical calculations. Another trick immersed a metal sphere in a magnetic field, with the changes in the field monitored as explosives imploded the sphere. John von Neumann had come up with a design for the implosion system, with George Kistiakowsky struggling to get it to work. It was not a simple thing, requiring an extremely precise and elaborate arrangement of explosives, but by March 1945 a workable implosion system was in hand.
Another issue was selection of an "initiator". Just slamming chunks of fissile material together wasn't quite enough to guarantee an explosive chain reaction; the core of the critical mass needed to contain a small amount of radioactive material, the initiator, to "kick-start" the chain reaction. Polonium was selected as the initiator and approved as an element of the production design. However, although considerable effort was expended to make sure all these pieces went together as planned, the only way to determine if they actually worked was to set off the bomb.
* Franklin Delano Roosevelt died of a stroke on 12 April 1945, and Vice-President Harry Truman became president of the United States. Truman did not know about the atomic bomb, though he was quickly briefed by Secretary of War Henry Stimson on the details. Truman had realized a few years earlier, while he was in the Senate and heading a watchdog committee, that there was major supersecret military research program in progress -- but then Stimson had told Truman that it was off-limits and should not be investigated. Truman had complied; there was a war on, after all.
Roosevelt's death was a shock to the nation. It was a particular shock to Leo Szilard, who had been chafing over the way his concerns about the future of the atomic bomb were being ignored in the high offices of the US government, as if there was "soundproof wall" around Washington DC where such concerns remained both unheard and unanswered. Szilard had gone back to his old friend Einstein and got a letter of introduction to the president, and also lined up a preliminary meeting with Eleanor Roosevelt, the first lady, for May.
Franklin Roosevelt's death forced a reset of Szilard's plans. The physicist did manage to arrange a meeting with James Byrnes, Truman's chief foreign policy advisor, who would become secretary of state in July. Accompanied by Harold Urey and Walter Bartkey, a dean of the University of Chicago, Szilard spoke to Byrnes in his South Carolina home. Szilard pointed out that the atomic bomb was a threat to the United States, since it gave smaller powers a weapon that could counter American material superiority, and that such a powerful weapon required a different mindset from any other weapon ever built. Byrnes was unimpressed, believing that the United States would be able to obtain a clear advantage from the atomic bomb, telling Szilard: "General Groves tells me there is no uranium in Russia."
Szilard was appalled, since he knew uranium is a surprisingly common element -- it was just a question of the quality of the ores and the amount of effort needed to get fissionable material out of it, availability not being a real issue. Szilard was particularly shocked at Byrnes' belief that the atomic bomb could be used to intimidate the Soviets, realizing very correctly that the end result of such an exercise would be to push the Soviets to develop their own atomic bomb at all costs. Szilard and his companions left empty-handed.
* On 30 April, Adolf Hitler committed suicide in his Berlin bunker. On 8 May, the Germans surrendered: the war in Europe was over. Late that April, Boris Pash's ALSOS group had discovered a German heavy-water atomic pile at Haigerloch, in the Black Forest region of southwestern Germany, and also rounded up the German nuclear scientists, including Werner Heisenberg. The German researchers had not been able to produce a sustained chain reaction, but they had been working their way up and didn't think they were too far away.
In other words, they weren't even up to the level the American Met Lab program had reached in late 1942. Pash was relieved to finally make sure that the Germans didn't have a working atomic bomb program. In fact, when the Los Alamos crew found out the specifics, they were astounded that the Germans had accomplished so little. Pash was also relieved to get his hands on the researchers before the Soviets did. The British locked up the researchers in a country manor in the UK, where there they concocted among themselves a tale that they had deliberately "dragged their feet" to prevent the Nazi leadership from getting the atomic bomb. Unknown to the prisoners, the house was wired with listening devices and the fiction didn't fly. Later on, Hans Bethe would sarcastically say of Heisenberg: "Dragged his feet? He didn't have feet to drag!"
* The B-29 Superfortress would never have an opportunity to drop a single bomb on Germany, but by the time of the Nazi surrender, it was making up for it by inflicting massive devastation on Japan. The first few months of B-29 raids from the Marianas hadn't delivered much in the way of effective results, and so in early 1945 Curt LeMay had been sent to take charge.
The problems were that Japanese weather tended to be cloudy, making targeting difficult, and there were also very surprising high-speed winds -- what would be later called the "jet stream" -- over Japan that played hell with high-altitude bombing. After some weeks of experimenting, LeMay figured he had the answer: low-level area bombing with clusters of small incendiary bombs -- metal tubes that shot out a stream of burning jellied gasoline on impact.
USAAF doctrine had always pushed precision bombing, few having much enthusiasm for bombing families out of their homes. However, as Superfortress bombing operations in Japan were showing, precision bombing was sometimes impractical and unworkable. It was well known that Japanese cities were full of lightly-built structures that were hideously vulnerable to fire, as had been proven by the disastrous Great Kantou Earthquake of 1923, which had caused immense damage to Tokyo and neighboring cities. In addition, Japanese manufacturing was structured around a network of small subcontractors, many of which operated out of residential districts or homes. If Japanese industrial facilities were a strategic target, by extension that made a whole city a legitimate target.
There was also the realization that an invasion of the Japanese home islands would cost many American lives. The determination of the Japanese to resist had been driven home by this time by the appearance of the "kamikaze", the "divine wind", in which Japanese pilots dived their bomb-laden aircraft directly into American warships. The Japanese were organizing every citizen to fight the invaders, which meant every Japanese citizen had in principle become a warrior, and so a legitimate target. Faced with such determined resistance, if the ugly choice came down to the mass killing of Japanese men, women, and children, or losing large numbers of American GIs -- to American leadership, that wasn't a choice at all.
LeMay had most of the defensive armament pulled off the Superfortresses. They would come in at low level in the dark, dropping their loads of incendiaries on flares dropped to mark the target. On the night of 9:10 March 1945, LeMay's airmen tried out these tactics for the first time, on Tokyo. Aided by the wind, the fires raged out of control, sweeping across the city like a wall of flame. Much of Tokyo was burned out; roughly 100,000 Japanese lost their lives, a million were left homeless. Losses among the Superfortress crews were light.
LeMay had finally determined the right formula. He turned his attention to the other major cities of Japan, methodically and ruthlessly gutting them out with fire, one by one. The Japanese had been taken by surprise by the Tokyo raid and were better prepared for the later attacks, resulting in considerably fewer civilian casualties. They were, however, unable to stop or even inflict major losses on the Superfortresses as the bombers put the torch to Japan's cities. The only thing that caused a breather in the destruction was when LeMay ran out of incendiaries, but more were being shipped across the Pacific.
The destruction of Japan's cities was all for the good as far as the American war effort was concerned, but it posed a problem for the atomic bomb program. In April, Groves had set up a high-level "Target Committee" to determine appropriate targets for the atomic bomb, but by that time the number of large cities left in anything resembling standing condition was decreasing rapidly. Dropping an atomic bomb on rubble and ashes didn't make much sense; as the committee's notes commented: "Tokyo is a possibility but it is now practically all bombed and burned out and is practically rubble with only the palace grounds left standing." The committee zeroed in on a short list, which included the city of Hiroshima: "Hiroshima is the largest untouched target not on the 21st Bomber Command priority list. Consideration should be given to this city."
The short list also included Kyoto, but Secretary of War Stimson, who found the idea of area bombing cities appalling in the first place, flatly told General Marshall that Kyoto, full of shrines and a center of Japanese cultural traditions, was not going to be bombed. Similarly, Stimson made it clear that reducing the imperial palace in Tokyo to radioactive ashes was not in the cards. That was equivalent to assassinating the Emperor, which few thought was a very good idea since it might well guarantee that every last Japanese fought to the death. Hiroshima increasingly began to seem like the most interesting target.
There was some talk at high levels of simply dropping the atomic bomb on a deserted area to impress the Japanese with its destructive capability. The idea was rejected. If the atomic bomb was dropped on an area where it did no real damage, why would the Japanese be all that impressed? They might simply conclude that they were witnessing some sort of fakery, a bomb that made a big bang but had little in the way of real teeth, and that the Americans were timid. At the time the United States, its leadership worried about a brutally costly invasion of the Japanese home islands, was hammering Japan with every weapon available. Truman was even considering use of poison gases, a notion that Roosevelt had emphatically rejected. If a new weapon became available, no matter how terrible it was, it would be used as well: anything, anything just to put an end to the war and the hideous wastage of American lives.
* By the spring of 1945, the time had come to select a site for the world's first detonation of an atomic bomb. In the spring of 1944, a Harvard experimental physicist named Kenneth T. Bainbridge, brought over from the MIT Rad Lab, had led a team to evaluate candidate sites. Eight locations were identified, with those nearest to Los Alamos regarded as the most convenient and attractive. Oppenheimer came along on the New Mexico field trips, partly because it allowed him to get away from his responsibilities as lab director for a time.
The site selected was on the northwest corner of the military's Alamogordo Bombing Range, about 340 kilometers (210 miles) south of the Los Alamos site. In early 1945, with progress on bomb development steaming along on track, Bainbridge was directed to prepare the site for the test, which was codenamed TRINITY. Bainbridge acquired a hefty staff and high-priority access to resources, with his people installing instrumentation systems at Alamogordo and a steel frame tower from which the blast would take place.
By the end of June, the bombs were going together and a plan, codenamed BRONX as a complement to MANHATTAN, was in place to ship production munitions across the Pacific to the Superfortresses that would deliver them. On 4 July 1945, the word came down from Washington DC to authorize use of the bombs. 4 July had been the initial target date for the TRINITY shot, but there had been minor delays, and there was also the issue of weather: the prevailing winds had to be in a direction that didn't take the dusty radioactive debris or "fallout" of the blast over populated areas. The actual schedule for TRINITY came down to 16 July, though it might have to be put off if the winds were unfavorable.
Los Alamos staff put together a betting pool on how big the blast would be. Enrico Fermi irritated the authorities by starting a pool to see if the bomb would set the atmosphere on fire, and if it did so, whether it would just destroy New Mexico or destroy the entire world. George Kistakowsky and his staff left Los Alamos in a truck convoy carrying the plutonium bomb assemblies just after midnight on 14 July -- the day before, Friday the 13th, hadn't seemed like a good time to head out. The bomb was assembled with great care and apprehension, and by the dark hours of the morning of 16 July 1945, all was ready to go.
Few got much sleep that night, and a thunderstorm lit up the darkness, fraying nerves further. Groves was assured the storm would pass and the test could go ahead on schedule, the decided time being 0530 AM. A Superfortress would be flying overhead at the time of the blast to see how much trouble it would cause a drop aircraft. At 0510 AM, the test countdown was initiated. Witnesses at the Alamogordo command center were told to lie face down in the sand before detonation, though some, such as Edward Teller, put on a welder's mask or smoked glasses so they could watch the explosion, from a distance of about 32 kilometers (20 miles). As the countdown ticked away, in the site command center the visibly stressed Oppenheimer muttered: "Lord, these affairs are hard on the heart." The countdown stepped relentlessly down to zero, and at 0530 AM, TRINITY went off, precisely on schedule.
There had been last-minute fears that the bomb was going to be a dud. It wasn't. Emilio Segre said later that even through dark glasses he had "an impression of an overwhelmingly bright light ... for a moment I thought the explosion might set fire to the atmosphere and finish the Earth, even though I knew that this was not possible." Another witness compared the flash of heat as like "opening a hot oven." The fireball rose up into the New Mexico sky and drove a hole through the clouds. Bainbridge commented: "Nobody who saw it could forget it, a foul and awesome display." He told Oppie: "Now we are all sons of bitches." Oppenheimer, drawing on his interest in Hindu mythology, thought of the words of the god Vishnu: "Now I am Death, the destroyer of worlds."
Yield was estimated at 19 kilotonnes (21 kilotons) of TNT; I.I. Rabi won the betting pool. There would be no test of the uranium bomb -- in fact, only hours after the test, the guts of the Little Boy weapon were put on board the cruiser USS INDIANAPOLIS in San Francisco. The warship then headed out to sea, bound for Tinian Island in the Marianas. Lighter components would be delivered by air.
* Most of the senior US government leadership was in Potsdam, Germany, at the time of the TRINITY shot, attending what would turn out to be the final high-level conference of the Allies. When War Secretary Stimson got the news there, he told a colleague: "Well, I have been responsible for spending two billions of dollars on this atomic venture. Now that it is successful, I shall not be sent off to prison at Fort Leavenworth." He informed Truman of the event. Although the Roosevelt Administration had been pushing the Soviets to join the war against Japan, the Truman Administration was increasingly suspicious of Soviet intentions and hoped that the atomic bomb could end the war in the Pacific before the USSR jumped in.
There was some reluctance to say much to Stalin about TRINITY, since it might just pressure him to intervene immediately lest he lose out on the spoils of the defeat of Japan. Truman vaguely told the Soviet leader that the United States had a "new weapon of unusual destructive force." Stalin merely nodded and replied that he was glad to hear of it and hoped that America "would make good use of it against the Japanese." Truman wasn't sure he had been understood; when the story got back to Oppenheimer, the physicist commented: "That was carrying casualness rather far."
Stalin was casual because Truman wasn't handing him any news. The Soviets knew all about Los Alamos and the American atomic bomb program, since it had been deeply penetrated by Red spies. Stalin accelerated plans for a military offensive in the Far East, making sure the USSR moved before the window of opportunity slid shut.
* During the spring of 1945, facilities for handling atomic bombs -- including an air-conditioned assembly facility and pits to allow the oversized bombs to be winched up into bombers -- were built on Tinian, with Tibbets' 509th Composite Group arriving in early June to prepare for action. The group was equipped with the latest B-29s, featuring improved engines, a lighter airframe, and a number of technical improvements. The crews practiced by flying to Iwo Jima and back, as well as bombing isolated Japanese island garrisons using ordinary general-purpose bombs and, later, pumpkins. Curt LeMay talked with Tibbets on plans for dropping the atomic bomb, the general saying that a low-level attack would be more accurate than a high-altitude drop. It seems that LeMay didn't quite understand what an atomic bomb could do; Tibbets made it clear that a low-level drop was neither necessary nor attractive.
The political wheels were turning towards the go-ahead for operational use of the atomic bomb. War Secretary Stimson knew the Japanese would resist an invasion of the home islands with absolute determination, but he did not accept the popular propaganda of the time that painted the Japanese as what he described as "mad fanatics of an entirely different mentality than ours." Stimson was aware of how rapidly the Japanese had moved from feudalism to a modern industrial society, and regarded them as both intelligent and pragmatic. Given the dire condition of Japan, Stimson thought that it would be sensible to send them an ultimatum, which would say that worse was coming but also provide reassurances concerning the all-important status of the Japanese Emperor.
By late July, Hiroshima had clearly moved to the top of the target list. On 26 July, the same day the cruiser USS INDIANAPOLIS arrived at Tinian with its atomic payload, the Allies issued an ultimatum to the Japanese, calling on them to surrender. It promised that, following occupation and demilitarization, Japan would become a free and independent democracy. Nothing was said one way or another about the status of the Emperor, the consensus being that it might encourage the Japanese to keep on fighting harder in hopes of getting a better deal. The next day the Japanese make it clear they were not willing to accept.
On 30 July, authorization was given to drop Little Boy on Hiroshima. The day before, 29 July, in one of the uglier stories of the war, the INDIANAPOLIS was torpedoed by the Japanese submarine I-58 in the Philippine Sea. The cruiser promptly went to the bottom. That wasn't the truly ugly part of the story; such misery is common in war. The ugly part was that, due to a ghastly bureaucratic screwup, nobody noticed the INDIANAPOLIS was missing for almost four days, during which time hundreds of sailors who might have been rescued drowned as their life vests became waterlogged, or were attacked by sharks, or went delirious from thirst.
* On 6 August 1945, Paul Tibbets took a Superfortress, named ENOLA GAY after his mother, off the runway at Tinian. It was bearing the Little Boy bomb and its target was Hiroshima. It was joined by two other B-29s, one an observer aircraft, the other a photo plane. When they arrived over the city at mid-morning, no great attention was paid on the ground to the intruders, since a serious attack on the city would have required a much larger force. The three bombers were judged likely to be on a reconnaissance mission.
At 9:15 AM, ENOLA GAY released its warload. At a predetermined altitude, a set of radar-based sensors set off the bomb, which detonated in a explosion rated at about 11 kilotonnes of TNT, orders of magnitude greater than that of any bomb ever used in war up to that time. The aircraft were hit by two hefty shockwaves, one directly from the blast and the other reflected from the ground. A huge mushroom cloud swelled up over the city. The weapon achieved destruction with a flash of incandescent energy, including high-energy radiation, and an explosive blast wave; buildings were smashed and fires sprung up over the city in an instant. The city center was leveled, tens of thousands of Japanese were killed immediately, and those on the edges of the blast were hideously burned or injured by debris. The radiation from the blast long-term environmental and public health damage.
The success of the attack on Hiroshima was promptly reported back up the chain of command. Les Groves called from Washington DC to tell Oppie the news: "I'm very proud of you and all your people."
Oppenheimer asked: "It went all right?"
"It went with a tremendous bang." Oppenheimer expressed satisfaction; when Leo Szilard got the news, he expressed anger, calling one of the "greatest blunders in history." To the surprise of some, the Japanese didn't surrender immediately. One of the difficulties was that Hiroshima had been so totally destroyed, with all communications disrupted, that it was hard for Tokyo to figure out what had happened. Japanese civilian leadership felt the destruction of Hiroshima meant that there would be no shame in surrender, but the military still wanted to fight to the last. B-29s dropped leaflets over Japanese cities announcing what had happened to Hiroshima and saying that Japan had to surrender or face more such attacks.
It wasn't an empty threat. On 9 August 1945, B-29s paid a similar visit to Nagasaki, with the B-29 BOCK'S CAR dropping the Fat Man bomb. Fat Man, which was essentially a production version of TRINITY, was well more powerful than Little Boy, but Nagasaki was a hillier target and the damage was not extensive. The destruction was still immense. Truman didn't want to drop more bombs for the moment, preferring to keep up conventional incendiary attacks while the Japanese thought things over.
The Japanese military still refused to quit, but the Emperor finally decided to exercise the authority he held but up to that time would not use. On 14 August he asked his ministers to draw up an edict announcing the surrender of Japan to the Allies, while a message indicating the desire to surrender was passed on to Allied diplomats through Switzerland. There was an attempt at a military coup to intercept the surrender, but the insurgents were suppressed and the Emperor's will prevailed. He read the edict to his people on 15 August, asking them to "bear the unbearable." World War II was over.
* The fighting was over, and for the moment the pressure was off. The Axis had been crushed, American soldiers were coming home in floods and demobilizing, America was literally throwing weapons away, in some cases flying brand-new combat aircraft straight from the factory to the scrapyard.
By September 1945, most of the physicists who had worked on the atomic bomb project were going back to peacetime work; Fermi, only half joking, suggested that it was time for scientists to figure out a cure for the common cold. The only serious activities going on at Los Alamos for the time being were packing up, saying goodbyes, and leaving. The lab would stay in business over the longer term, but its staffing abruptly fell in half, and it would no longer be a concentration of the scientific elite.
Although the US was in retreat from its wartime posture as a military superpower, the Soviet Union was not. Despite his seeming indifference to Truman, Josef Stalin had found the American development of the Bomb disturbing, particularly because they had actually used the thing. If they used it once, they would almost certainly use it again. Now that Hitler was dead and the Americans were arming themselves with nuclear weapons, the Soviet atomic bomb project went from an investigation effort to a full-blown development program. With Hiroshima, Stalin had got the message and the atomic bomb development effort went to the absolute top of the priority queue, taking precedence over rebuilding the USSR's shattered cities. Soviet citizens might go homeless and hungry, but the Soviet Union would have an atomic bomb, regardless of the expense or environmental damage.
Late in 1945, the US embassy in Moscow passed on leaks that the Soviets did have an atomic bomb development program in progress. There was, however, a tendency to regard the USSR as more backwards than it really was. A joke made the rounds that the only way the Soviets could attack the USA with a nuclear weapon was by smuggling it in using a suitcase -- but then they'd have to refine the suitcase first.
The Americans had greatly overestimated the German capability to build an atomic bomb, and now went to greatly underestimating the Soviet capability to develop such a weapon. As Leo Szilard had taken pains to point out, there was nothing magical about a nuclear weapon: if one nation could build it, in principle so could another. Kurchatov's group included world-class scientific minds and the Soviets were capable of mobilizing massive industrial resources. Very significantly, they also had almost all the information they wanted on the American atomic bomb program: there were at least three Red spies inside Los Alamos. The most important of the trio was Klaus Fuchs, who passed on plans of the Fat Man bomb to the Soviets. Although Soviet physicists believed they could design their own atomic bomb, given the extreme pressure to get results, the easiest thing to do was to just copy the Fat Man bomb.
* In early 1948, the US was served notice that hopes for a peaceful postwar world order were unrealistic. Stalin ordered a blockade of Berlin, cutting off power and ground access to the city. The US and Britain organized an airlift to resupply Berlin by air, with transport aircraft arriving in precisely-planned schedules every few minutes over a period of eight months. Stalin had been outmaneuvered, given a taste of the material power of the Americans. He chose not to escalate the confrontation by interfering with the airlift.
By the summer of 1949, Kurchatov and his researchers went to the steppes of Kazakhstan to complete preparations for the first Soviet atomic bomb test. It took place in August. The blast was kept a secret, but not long before the shot some American researchers had been prudent enough to suggest that Soviet nuclear activities needed to be monitored, even though the conventional wisdom was that the USSR wasn't close to developing a bomb. An organization was set up to do the monitoring.
Following the test, a B-29 carrying air filter systems picked up the airborne radioactive fallout from the test. After checking the samples carefully, on 24 September 1949, the Americans announced that the Soviet Union had detonated an atomic weapon. The announcement caught Stalin completely off guard. He had believed the secret could be kept, and the detection of the blast was another unsettling bit of evidence of the technical lead of the West, though in fact the Americans would have missed it if it had occurred much earlier.
If the Berlin blockade had been a wakeup call, the Soviet Bomb was a fire alarm. America had to mobilize to deal with the threat by all means short of an all-out shooting match. Both sides went on to stockpile atomic bombs and go on to develop fusion bombs: Edward Teller's super bomb became a reality. Oppenheimer was prominent among those who tried to apply the brakes, but there was no stopping the momentum. Oppie ended up humiliated, discredited in public hearings by the lies he had told the Army security people; he was stripped of his security clearance and pushed to the political sidelines. Both sides accumulated weapons at rapid pace
This state of belligerent armed peace would acquire a name: the Cold War. It would last for almost half a century as a demonstration of how the atomic bomb had permanently changed the world.