Isegoria

Admiral Purnell and General Groves had often discussed the importance of having the second blow follow the first one quickly, as General Groves explains (in Now It Can Be Told: The Story of the Manhattan Project), so that the Japanese would not have time to recover their balance:

It was Purnell who had first advanced the belief that two bombs would end the war, so I knew that with him and Farrell on the ground at Tinian there would be no unnecessary delay in exploiting our first success.

Good weather was predicted for the ninth, with bad weather to follow for the next five days. This increased the urgency of having the first Fat Man ready still another day earlier. When the decision to do so was reached, the scientific staff made it clear that in their opinion the advancement of the date by two full days, from the eleventh to the ninth, would introduce a considerable measure of uncertainty. I decided, however, that we should take the chance; fortunately all went well with the assembly, and the bomb was loaded and fully checked by the evening of August 8.

Six Pumpkin-carrying planes were assigned various targets in Japan for the eighth, but because of weather only two of them reached their primary targets; three of them reached secondary targets, and one aborted and returned to Tinian. In the field order for the second atomic mission there was nothing to indicate the extraordinary nature of the bomb, although anyone reading it would realize that this was by no means a routine assignment.

There were only two targets designated this time: Kokura, primary; and Nagasaki, secondary. Niigata was not made a third target because of its great distance from the other two cities.

[…]

The Kokura arsenal was one of the largest war plants in Japan. It produced many different weapons and pieces of war equipment. It extended over almost two hundred acres and was supported by numerous machine shops, parts factories, electric power plants and the usual utilities.

Nagasaki was one of Japan’s largest shipbuilding and repair centers. It was important also for its production of naval ordnance. It was a major military port. The aiming point was in the city, east of the harbor.

[…]

It was not possible to “safe” the Fat Man by leaving the assembly incomplete prior to take-off, as had been done in the case of the Little Boy. There was considerable discussion among the technical staff about what would happen if the plane crashed, and possibly caught fire, while it was taking off. They realized that there would be a serious chance that a wide area of Tinian would be contaminated if the plutonium were scattered by a minor explosion; some thought that there was even a risk of a high-order nuclear explosion which could do heavy damage throughout the island’s installations. Of course, we had gone into all this at length during our preliminary planning, and on the basis of my own opinion, as well as that of Oppenheimer and my other senior advisers, that the risk was negligible I had decided that the risk would be taken.

As happens so often, however, there was constant interference by various people in matters that lay outside their spheres of responsibility. Throughout the life of the project, vital decisions were reached only after the most careful consideration and discussion with the men I thought were able to offer the soundest advice. Generally, for this operation, they were Oppenheimer, von Neumann, Penney, Parsons and Ramsey. I had also gone over the problems at considerable length with the various groups of senior men at Los Alamos, and had discussed them thoroughly with Conant and Tolman and with Purnell and Farrell and to a lesser degree with Bush. Yet in spite of this, some of the people on Tinian again raised the question of safety at take-off at the last moment. Their fears reached a senior air officer, who asked for a written statement to the effect that it would be entirely safe for the plane to take off with a fully armed bomb. Parsons and Ramsey signed such a statement promptly though with some trepidation, possibly with the thought that if they were proven wrong they would not be there to answer. Ramsey then advised Oppenheimer at once of the various design changes that must be made to ensure that future bombs would in fact be surely safe.

One very serious problem came up just before take-off, which placed Farrell in the difficult position of having to make a decision of vital importance without the benefit of time for thought or consultation. Despite all the care that had been taken with the planes, the carrying plane was found at the last moment to have a defective fuel pump, so that some eight hundred gallons of gasoline could not be pumped to the engines from a bomb bay tank. This meant that not only would the plane have to take off with a short supply of fuel, but it would have to carry the extra weight of those eight hundred gallons all the way from Tinian to Japan and back. The weather was not good, in fact it was far from satisfactory; but it was good enough in LeMay’s opinion, and in view of the importance of dropping the second bomb as quickly as possible, and the prediction that the weather would worsen, Farrell decided that the flight should not be held up. Just before take-off Purnell said to Sweeney, “Young man, do you know how much that bomb cost?” Sweeney replied, “About $ 25 million.” Purnell then cautioned, “See that we get our money’s worth.”

Because of the weather, instead of flying in formation, the planes flew separately. To save fuel, they did not fly over Iwo Jima but went directly to the coast of Japan. Their plan was to rendezvous over the island of Yokushima, but this did not work out. The planes were not in sight of each other during their overwater flight and only one of the observation planes arrived at the rendezvous point. The missing plane apparently circled the entire island instead of one end of it, as it was supposed to do according to Sweeney’s plans. Although Sweeney had identified the one plane that did arrive he did not tell Ashworth. Unfortunately, because it did not come close enough, Ashworth was unable to determine whether it was the instrument-carrying plane, which was essential to the full completion of the mission, or the other, which was not. Sweeney’s orders were to proceed after a short delay of fifteen minutes but he kept waiting hopefully beyond the deadline. The result was a delay of over half an hour before they decided to go on to Kokura, anyway.

At Kokura, they found that visual bombing was not possible, although the weather plane had reported that it should be. Whether this unexpected condition was due to the time lag, or to the difference between an observer looking straight down and a bombardier looking at the target on a slant, was never determined.

After making at least three runs over the city and using up about forty-five minutes, they finally headed for the secondary target, Nagasaki. On the way they computed the gasoline supply very carefully. Ashworth confirmed Sweeney’s determination that it would be possible to make only one bombing run over Nagasaki if they were to reach Okinawa, their alternate landing field. If more than one run had to be made they would have to ditch the plane—they hoped near a rescue submarine.

At Nagasaki, there was a thick overcast and conditions at first seemed no better for visual bombing than at Kokura. Considering the poor visibility and the shortage of gasoline, Ashworth and Sweeney decided that despite their positive orders to the contrary, they had no choice but to attempt radar bombing. Almost the entire bombing run was made by radar; then, at the last moment, a hole in the clouds appeared, permitting visual bombing. Beahan, the bombardier, synchronized on a race track in the valley and released the bomb. Instead of being directed at the original aiming point, however, the bomb was aimed at a point a mile and a half away to the north, up the valley of the Urakami River, where it fell between two large Mitsubishi armament plants and effectively destroyed them both as producers of war materials.

On the way to Okinawa warning ditching orders were announced; but the plane made it with almost no gas left. Sweeney reported there wasn’t enough left to taxi in off the runway.

The Nagasaki bomb was dropped from an altitude of 29,000 feet. Because of the configuration of the terrain around ground zero, the crew felt five distinct shock waves.

The missing observation plane, which fortunately was the one without the instruments, saw the smoke column from a point about a hundred miles away and flew over within observing distance after the explosion. Because of the bad weather conditions at the target, we could not get good photo reconnaissance pictures until almost a week later. They showed 44 per cent of the city destroyed. The difference between the results obtained there and at Hiroshima was due to the unfavorable terrain at Nagasaki, where the ridges and valleys limited the area of greatest destruction to 2.3 miles (north-south axis) by 1.9 miles (east-west axis). The United States Strategic Bombing Survey later estimated the casualties at 35,000 killed and 60,000 injured.

While the blast and the resulting fire inflicted heavy destruction on Nagasaki and its population, the damage was not nearly so heavy as it would have been if the correct aiming point had been used. I was considerably relieved when I got the bombing report, which indicated a smaller number of casualties than we had expected, for by that time I was certain that Japan was through and that the war could not continue for more than a few days.

To exploit the psychological effect of the bombs on the Japanese, we had belatedly arranged for leaflets to be dropped on Japan proclaiming the power of our new weapon and warning that further resistance was useless. The first delivery was made on the ninth, the day of the Nagasaki bombing. The following day General Farrell canceled the drops, when the surrender efforts of the Japanese made any further such missions seem ill-advised.

General Marshall expressed his feeling that we should guard against too much gratification over our success, as General Groves explains (in Now It Can Be Told: The Story of the Manhattan Project), because it undoubtedly involved a large number of Japanese casualties:

I replied that I was not thinking so much about those casualties as I was about the men who had made the Bataan death march. When we got into the hall, Arnold slapped me on the back and said, “I am glad you said that — it’s just the way I feel.” I have always thought that this was the real feeling of every experienced officer, particularly those who occupied positions of great responsibility, including General Marshall himself.

August 1, 1945 came and passed, General Groves explains (in Now It Can Be Told: The Story of the Manhattan Project), and the weather was not favorable over Japan. General LeMay did not think that it would be wise to undertake the mission under those conditions:

The six crews that might be used were given special instructions on the procedures they were to follow, and at another briefing on August 4, Parsons explained the effects they could expect when the bomb exploded. Most of them knew by now that they were dealing with a special type of bomb, but Parsons’ statement that the force of the explosion would be equivalent to that of twenty thousand tons of TNT came as a complete surprise.

During the period of waiting, the special air-sea rescue plans were settled. They emphasized that no other aircraft would be permitted within fifty miles of the target during a period of from four hours before until six hours after strike time. Not even for rescue operations would this restriction be lifted. Special air-sea rescue facilities were to be provided by both Army and Navy planes and by submarines, and in spite of the necessary restrictions we had placed upon it, rescue coverage in this operation would be far better than average.

[…]

Other air attacks on Japan were to be carried out on the same day as our mission, to divert any Japanese defense actions that might endanger our operation. Hiroshima would be the primary target, with Kokura Arsenal and Kokura the secondary targets, and Nagasaki the tertiary target. The aiming point for Hiroshima was close to the Japanese Army Headquarters.

Hiroshima was a highly important military objective. The Army Headquarters was located in a castle. Some 25,000 troops were in its garrison. It was the port through which all supplies and communications passed from Honshu to Kyushu. It was the largest city, excepting Kyoto, that was still undamaged by American air raids. Its population was believed to be over 300,000, and it was a beehive of war industry, carried on in moderate-sized plants and in small shops as well as in almost every home.

We would use a total of seven planes. One would be sent to Iwo Jima to serve as a spare in case the bomb-carrying plane developed mechanical troubles on the flight from Tinian. Three planes would go ahead, one to each target area, to appraise the local weather and to relay the information back to the bomb-carrying plane, which would be accompanied by two observer planes to the general vicinity of the target. One of these carried special measuring and recording instruments, including some that would be dropped near the target to radio back their readings.

Radar was to be used as an aid but the actual bombing was to be accomplished visually. If this proved to be impossible, the bomb was to be brought back, probably to Iwo Jima, as the plane’s gas supply might not permit the return to Tinian. We were anxious to avoid having it come down at other air bases, for in case of a landing accident we wanted personnel on the ground who would be aware of the special precautions that would have to be taken.

[…]

Provisions were also made for the strike photographs to be taken by the 3rd Photo Reconnaissance Squadron and two photo crews were briefed on their assignment by the 509th’s intelligence officers.

[…]

Parsons had decided with Farrell’s approval to complete the final assembly of the bomb after takeoff. His purpose was to minimize the hazards of a crash on Tinian. I had previously said that I was opposed to this as unwise, because it was unnecessary and because it would be very difficult to do it in cramped conditions in the plane. I was not informed of the plan until it was too late to interfere.

[…]

The original scheduled time was 0915. Thus, in a flight of some seventeen hundred miles taking six hours and a half, Colonel Tibbets had arrived on target only one-half of a minute off schedule.

The 20th Air Force order covering the operation prescribed a turn of 150° after the bomb was released in order to gain a maximum distance from the point of explosion; such a turn, our studies indicated, could be made without undue risk to the plane and its crew.

Immediately after the bomb was dropped from 31,600 feet, the plane began its getaway maneuver. The flash was seen during this turn and fifty seconds after the drop, the shock waves hit the plane. There were two of these, the first the direct shock wave and the second the reflected wave from the ground. By that time the plane was fifteen miles away from the burst.

[…]

The crews of the strike and the two observation aircraft reported that five minutes after release a dark gray cloud of some three miles in diameter hung over the center of Hiroshima. Out of the center of this grew a column of white smoke which rose to a height of 35,000 feet, with the top of the cloud being considerably enlarged.

Four hours after the strike, the photo reconnaissance planes found that most of the city of Hiroshima was still obscured by the smoke cloud, although fires could be seen around its edges.

[…]

Pictures taken the following day showed that 60 per cent of the city was destroyed.

The area devastated at Hiroshima was 1.7 square miles, extending out a mile from ground zero. The Japanese authorities estimated the casualties at 71,000 dead and missing and 68,000 injured.

The most important result achieved by the Hiroshima bombing was not the physical damage, although over 50 per cent of the buildings were totally destroyed, nor was it the fifteen to twenty thousand Japanese soldiers who were killed or severely wounded, nor was it the thousands of other people killed and injured. The important result, and the one that we sought, was that it brought home to the Japanese leaders the utter hopelessness of their position. When this fact was re-emphasized by the Nagasaki bombing, they were convinced that they must surrender at once.

Parsons reported (in special one-time code, of course):

Results clearcut, successful in all respects. Visible effects greater than New Mexico tests. Conditions normal in airplane following delivery.

Received at the same time was this message relayed from the plane:

Target at Hiroshima attacked visually. One-tenth cloud at 052315Z. 3 No fighters and no flak.

The Alamogordo test, General Groves explains (in Now It Can Be Told: The Story of the Manhattan Project), had not set aside all doubts about the bomb:

It proved merely that one implosion-type, plutonium bomb had worked; it did not prove that another would or that a uranium bomb of the gun type would. We had made every possible component test we could think of. We were reasonably sure of each one. We knew we could bring the U-235 portions of the bomb together in such a way that, if the theories of atomic energy were correct and U-235 behaved as plutonium had, the bomb should go off. But still no test had been made of the complete bomb. Nevertheless, the indications for success were strong enough so that no one urged us to change our plans of dropping the first gun-type bomb in combat without prior test. In any case, we simply had to take the chance, because the production of U-235 was so slow, even compared to plutonium, that we could not afford to use it in a test.

[…]

Early in the morning of July 16, the bomb — minus the last necessary bit of U-235 — was put aboard the cruiser Indianapolis, which sailed almost immediately. The Indianapolis had a fast but uneventful trip through Hawaii to Tinian.

[…]

The Indianapolis arrived at Tinian on July 26 and discharged her cargo that same day. She then put out to sea, headed for the Philippines, but her voyage came to a sudden and tragic end on July 30 when she was attacked by a Japanese submarine and went down with some nine hundred of her crew.

[…]

I had arranged with Lieutenant General H. L. George, the head of Air Transport, for the final parts, including some U-235, of the Hiroshima bomb to be flown from Albuquerque to Tinian. Because I did not want to risk having the plane disappear in flight with an extremely valuable though small piece of U-235, I asked for two large cargo planes in perfect condition, and the best possible crews. I told George that the cargo would be almost infinitesimal and that the second plane was wanted just in case of need, to tell us where the first one crashed — if it did. George had had his orders from Arnold and he simply said, “Whatever you want, you get.”

[…]

The flight to San Francisco was uneventful but when they were about forty-five minutes out over the Pacific, de Silva’s plane had to return to the mainland because of engine trouble. Contrary to what I had counted on, Taylor’s plane, instead of returning too, continued directly to Hawaii and arrived there several hours before de Silva’s plane came in. Despite our desire to keep the flight inconspicuous, a radio tip — probably sent unofficially — alerted Hawaii to a very important flight, and Taylor was met at the airfield by a group of senior officers who expected at least one high-ranking general with entourage instead of a single second lieutenant. Taylor had no written orders with him, since they were in de Silva’s hands, and soon found the local personnel determined, in accordance with custom, to load the empty plane to capacity. Fortunately, the plane crew had been convinced before departure from California that the trip was most unusual and with their support he was able to keep the ship unloaded until de Silva arrived. From then on the trip was uneventful.

[…]

One of our big problems had been whether to use each bomb as it became available or to store up a sufficient number to permit their employment in quantity. Most professional soldiers will go to almost any length to avoid piecemealing away their resources. However, in this case, we felt that the considerations of time and expected power justified our using the weapons as they became available. If our assessment of these factors had been erroneous, our position might very well have been extremely embarrassing, for our projected production rates called for one Fat Man of the type we had tested at Alamogordo (but not by an air drop) to be delivered at Tinian on about August 6, with a second one to be ready about August 24, and additional ones arriving in increasing numbers from there on.

As I have said, we had no assurance that a uranium bomb, the Thin Man, would work at all. Yet, that was the weapon that we employed against Hiroshima, since we had used up our entire immediate supply of plutonium in the test bomb.

[…]

General Marshall was also furnished with the probable readiness dates of the implosion bomb, and I explained that there would have to be a gap of at least three days between successive bombs, no matter what type was used. I did not give him the reason for this: we needed the time to assemble the bomb, and nothing should be hurried. Judging by the Alamogordo test, I said, we now expected this bomb to have an explosive force exceeding the equivalent of ten thousand tons of TNT and possibly reaching as high as thirty thousand tons.

[…]

Many small problems arose as the date of the first bombing approached. Two years before, the War Department had issued orders prohibiting persons with knowledge of future military operations from flying over enemy-held territory. The reason for this order was sound — to prevent leakage of information through possible prisoners of war — but it created an impossible situation for us. We had to have Parsons and Ashworth and their two technical assistants aboard the bombing planes. We also needed Tibbets and his best pilots on these flights, and we wanted to have certain scientists in the observation planes. We simply could not operate under such a restriction.

When this problem was brought to my attention in Washington, I immediately secured War Department authority to disregard the prohibition for both civilian and military personnel concerned with Centerboard, as our overseas operation had been named, provided their flights were essential.

Throughout the period when they were planning the atomic bombing operations against Japan, General Groves explains (in Now It Can Be Told: The Story of the Manhattan Project), American strategy was based upon the assumption that an invasion of the Japanese homeland was essential to ending the war in the Pacific:

Under the strategic concept approved by the Joint Chiefs in July of 1944, Kyushu was to be invaded on October 1, 1945, with the final assault on Tokyo following in December of that year. This plan was not dependent in any way upon Russian co-operation.

After the Yalta Conference, however, a debate sprang up over whether it would not be better to encircle Japan and defeat her by attrition than to defeat her by direct attack. Both General MacArthur and Admiral Nimitz, when asked for their opinion, voted for a direct assault.

[…]

It was estimated that a force of 36 divisions—1,532,000 men in all—would be required for the final assault, and it was recognized that casualties would be heavy.

The Joint Chiefs of Staff approved the concept and on May 25 the directive for the Kyushu invasion was issued to General MacArthur, Admiral Nimitz and General Arnold. The target date for the invasion of Kyushu was now November 1, 1945.

[…]

However, one very important question arose: should the United States delay any contemplated military action in the expectation that an effective atomic bomb would be produced as scheduled? To any experienced soldier it was obvious that, once an advantage had been gained over an enemy as dangerous as Japan, no respite should be given. If the bomb had been scheduled for delivery in early November, a few days after the scheduled date of the Kyushu invasion, I would have advised a delay in the landing operation. I expressed this point of view in conversations with Secretary Stimson and Harvey Bundy, but I also told them and General Marshall that I would consider it a serious mistake to postpone any feasible military operation in the expectation that the bomb would be ready as a substitute at some later date.

[…]

Decisions of this nature must always be made by only one man, and, in this case, the burden fell upon President Truman.

[…]

As far as I was concerned, his decision was one of noninterference—basically, a decision not to upset the existing plans.

When we first began to develop atomic energy, the United States was in no way committed to employ atomic weapons against any other power. With the activation of the Manhattan Project, however, the situation began to change. Our work was extremely costly, both in money and in its interference with the rest of the war effort. As time went on, and as we poured more and more money and effort into the project, the government became increasingly committed to the ultimate use of the bomb, and while it has often been said that we undertook development of this terrible weapon so that Hitler would not get it first, the fact remains that the original decision to make the project an all-out effort was based upon using it to end the war. As Mr. Stim-son succinctly put it, the Manhattan Project existed “to bring the war to a successful end more quickly than otherwise would be the case and thus to save American lives.”

[…]

The first serious mention of the possibility that the atomic bomb might not be used came after V-E Day, when Under Secretary of War Patterson asked me whether the surrender in Europe might not alter our plans for dropping the bomb on Japan.

[…]

At this same time a debate arose about how the bomb should be employed. Should we conduct a demonstration of its power for all the world to see, and then deliver an ultimatum to Japan, or should we use it without warning? It was always difficult for me to understand how anyone could ignore the importance of the effect on the Japanese people and their government of the overwhelming surprise of the bomb. To achieve surprise was one of the reasons we had tried so hard to maintain our security.

President Truman knew of these diverse and conflicting opinions. He must have engaged in some real soul-searching before reaching his final decision. In my opinion, his resolve to continue with the original plan will always stand as an act of unsurpassed courage and wisdom—courage because, for the first time in the history of the United States, the President personally determined the course of a major military strategical and tactical operation for which he could be considered directly responsible; and wisdom because history, if any thought is given to the value of American lives, has conclusively proven that his decision was correct.

[…]

I had set as the governing factor that the targets chosen should be places the bombing of which would most adversely affect the will of the Japanese people to continue the war. Beyond that, they should be military in nature, consisting either of important headquarters or troop concentrations, or centers of production of military equipment and supplies. To enable us to assess accurately the effects of the bomb, the targets should not have been previously damaged by air raids. It was also desirable that the first target be of such size that the damage would be confined within it, so that we could more definitely determine the power of the bomb.

[…]

One of the most difficult problems was attempting to estimate, or even guess, the probable explosive force of the weapon. An accurate guess was of vital importance because the closer we came to being right, the more effective the bomb would be. The optimum height of burst was entirely governed by the explosive force. If the altitude of burst we used was below or too high above this optimum, the area of effective damage would be reduced; and it was possible, if it was much too high, that all we would produce would be a spectacular pyrotechnical display which would do virtually no damage at all. We calculated that if the bomb was detonated at 40 per cent below optimum altitude or 14 per cent above, there would be a reduction of 25 per cent in the area of the severe damage.

At first, considerations of possible fallout and of direct radiation definitely favored a burst at a maximum altitude. I had always insisted that casualties resulting from direct radiation and fallout be held to a minimum. After the Alamogordo test, when it became apparent that the burst could be many hundreds of feet above the ground, I became less concerned about radioactive fallout from too low a burst.

For the present, however, since we did not know the size of the explosion, our plans had to be based on conservative detonation heights. For the Little Boy, it was estimated that the explosive force would have a TNT equivalent ranging from 5,000 to 15,000 tons. For this weapon, the corresponding desirable height of detonation would vary then from 1,550 feet to 2,400 feet. For the Fat Man, it was thought that the magnitude of the explosion would range from 700 to 5,000 tons. This would require detonating heights between 700 feet and 1,500 feet. We could only hope that we could tighten up these estimates considerably, particularly for the Fat Man, after testing the implosion bomb. This element of doubt meant that we had to have fuses for four different height settings. By then most of us in the project were thoroughly inured to such uncertainties. Indeed, three days later, on May 14, Oppenheimer informed me that he and von Neumann had concluded after a thorough discussion that the probable explosive power of the Fat Man was still uncertain, and that the views of the Target Committee should be amended accordingly. They estimated that the maximum altitude for which we should be prepared to set fuses was about twice the minimum, and even for the Little Boy the minimum and probable altitude was only two-thirds of the maximum.

It was agreed that visual bombing was so important from the standpoint of hitting the target that we should be prepared to await good weather. This was based on an estimate that there was only a 2 per cent chance that we would have to wait over two weeks.

The committee recommended that we have spotter aircraft over each of the three alternative targets so that the final target could be selected in the last hour of flight. In case the delivery plane should reach the target and find visual bombing to be impossible, they thought it should return to its base with the bomb. The drop should be made with radar only if the plane could not otherwise return. Radar and navigational developments should be followed closely so that these conclusions could be altered, if desirable.

We all recognized that the plan to use visual bombing, with the possible long delays entailed, required that the bomb be so designed that it could be held for at least three weeks in a state of readiness that would permit its being dispatched on twelve hours’ notice. This was not considered too great a problem at the time, and later we could ignore it as it became obvious that we would normally have at least forty-eight hours’ notice of possible suitable weather.

It was generally agreed that if a plane in good condition had to return to base with the bomb, it would probably be able to make a normal landing. Frequent practice landings had been made with dummy bombs, some of them filled with high explosives. The committee advised that special training in landing with dummy units should be given to all plane crews who were to carry the bomb.

If the bomb had to be jettisoned, extreme care would have to be exercised. Under no circumstances should it be jettisoned near American-held territory. Prior to actual take-off, definite instructions would have to be furnished the weaponeer to guide him in case of trouble. Careful calculations and the experience gained by the Air Force in England from missions involving bombs as large as two thousand pounds indicated that there was no reason to fear for the safety of the bombing plane if its flight were properly controlled. Discussion of the possible radiological effects did indicate, however, that it would be unwise for any aircraft to be closer than two and a half miles to the burst. To provide protection against blast effects, a distance of five miles was advisable. Also, no plane should be permitted to fly through the radioactive clouds.

[…]

They had assumed that the atomic bomb would be handled like any other new weapon; that when it was ready for combat use it would be turned over to the commander in the field, and though he might be given a list of recommended targets, he would have complete freedom of action in every respect.

[…]

I had always assumed that operations in the field would be closely controlled from Washington, probably by General Marshall himself, with Mr. Stimson fully aware of and approving the plans. Naturally I expected that the President also would share in the control, not so much by making original decisions as by approving or disapproving the plans made by the War Department. It was quite evident by now, however, that the operation would not be formally considered and acted upon by either the Joint Chiefs of Staff or the Combined Chiefs. One of the reasons for this was the need to maintain complete security. Equally important, though, was Admiral Leahy’s disbelief in the weapon and its hoped-for effectiveness; this would have made action by the Joint Chiefs quite difficult.

When I had visited him in his office six or seven months before to show him a status report on the project, he told me of his long experience with explosives in the Navy and emphasized his belief that nothing extraordinary would come out of our work. He reminded me that no weapon developed during a war had ever been decisive in that war. Then he went on to say he was sorry that I was involved in the project as it would have been much better for me to have had a different and more usual assignment.

[…]

The cities that the Target Committee finally selected, and which I approved without exception, were:

Kokura Arsenal, one of the largest munitions plants in Japan, which was engaged in the manufacture of a wide variety of weapons and other defense materials. The arsenal covered an area of about four thousand by two thousand feet and was contiguous to railway yards, machine shops and electric power plants.

Hiroshima, a major port of embarkation for the Japanese Army and a convoy assembly point for their Navy. The city, in which the local Army headquarters, with some twenty-five thousand troops, was situated, was mainly concentrated on four islands. The railway yards, Army storage depots and port of embarkation lay along the eastern side of the city. A number of heavy industrial facilities were adjacent to the main metropolitan area.

Niigata, a port of growing importance on the Sea of Japan. It contained an aluminum reduction plant, and a very large ironworks, together with an important oil refinery and a tanker terminal.

Kyoto, an urban industrial area with a population of about one million inhabitants. It was the former capital of Japan, and many displaced persons and industries were moving into it as other areas were destroyed. Also, it was large enough to ensure that the damage from the bomb would run out within the city, which would give us a firm understanding of its destructive power.

[…]

When I went over the list for him, he immediately objected to Kyoto and said he would not approve it. When I suggested that he might change his mind after he had read the description of Kyoto and our reasons for considering it to be a desirable target, he replied that he was sure that he would not.

The reason for his objection was that Kyoto was the ancient capital of Japan, a historical city, and one that was of great religious significance to the Japanese. He had visited it when he was Governor General of the Philippines and had been very much impressed by its ancient culture.

I pointed out that it had a population of over a million; that any city of that size in Japan must be involved in a tremendous amount of war work even if there were but few large factories; and that the Japanese economy was to a great extent dependent on small shops, which in time of war turned out tremendous quantities of military items. To reinforce my argument, I read from the description of Kyoto,, included in my report, which had now arrived. I pointed out also that Kyoto included 26,446,000 square feet of plant area that had been identified and 19,496,000 square feet of plant area as yet unidentified. The city’s peacetime industries had all been converted to war purposes and were producing, among other items, machine tools, precision ordnance and aircraft parts, radio fire control and gun direction equipment. The industrial district occupied an area of one by three miles in the total built-up area of two and one-half by four miles.

Mr. Stimson was not satisfied, and without further ado walked over to the door of General Marshall’s office and asked him to come in. Without telling him how he had got the report from me, the Secretary said that he disagreed with my recommendation of Kyoto as a target, and explained why. General Marshall read the target description of each of the four cities, but he did not express too positive an opinion, though he did not disagree with Mr. Stimson. It was my impression that he believed it did not make too much difference either way.

[…]

In the course of our conversation he gradually developed the view that the decision should be governed by the historical position that the United States would occupy after the war. He felt very strongly that anything that would tend in any way to damage this position would be unfortunate.

On the other hand, I particularly wanted Kyoto as a target because, as I have said, it was large enough in area for us to gain complete knowledge of the effects of an atomic bomb. Hiroshima was not nearly so satisfactory in this respect. I also felt quite strongly, as had all the members of the Target Committee, that Kyoto was one of the most important military targets in Japan. Consequently, I continued on a number of occasions afterward to urge its inclusion, but Mr. Stimson was adamant.

[…]

Nothing is more illustrative of the relationship between Secretary Stimson and me than this episode. Never once did he express the slightest displeasure or annoyance over my repeated recommendations that Kyoto be returned to the list of targets. Nor did I ever feel that he wanted me to remain silent, once I had learned his views, on a matter of such great importance. I believe the affair was also typical of his attitude toward other senior officers.

Events have certainly borne out the wisdom of Mr. Stimson’s decision. I think, however, he did not foresee that much of the criticism he so scrupulously sought to avoid would come from American citizens; certainly he never mentioned this possibility to me. After the sudden ending of the war I was very glad that I had been overruled and that, through Mr. Stimson’s wisdom, the number of Japanese casualties had been greatly reduced.