There has never been an improvement in weapons comparable in degree and in sudden impact to the atomic bomb. In the case of other developments, such as explosives, the airplane, the tank, long-range artillery, armor-clad warships, submarines, and even rifles, it took years, if not decades and centuries, after their first use for their revolutionary influence upon warfare to be felt. In the case of the atomic bomb it took only a few hours.
In employing it in battle, the Army Air Force would obviously play a major role, provided, of course, that the bomb could be airlifted. Consequently, I called on General H. H. Arnold in the spring of 1944 and discussed the whole situation with him, including our prospects for success and the date upon which the bomb would probably be ready. He had previously been told about the project in very general terms; now, I wanted to fill him in more completely and to make certain of his support.
In calling upon him at this time, I was, of course, assuming that our work would be successful. This was normal procedure. Always we assumed success long before there was any real basis for the assumption; in no other way could we telescope the time required for the over-all project. We could never afford the luxury of awaiting proof of one step before proceeding with the next. Just as we nearly finished building and equipping the gaseous diffusion plant before we knew that we could make its most vital part, the barrier, so here we began to prepare for combat operations a year before we knew that we could produce an atomic explosion.
We were also still uncertain about the final size and weight of the implosion bomb, although we were quite certain of these factors for the gun type. However, after discussing this problem with Oppen-heimer and his senior associates at Los Alamos, I had decided it would be reasonable to plan on using the B-29 as the carrier plane for both types, though we might have to make certain modifications, all of which appeared feasible, in the plane’s bomb bay and bomb-handling equipment. Nevertheless, we all recognized that problems then unforeseen might make the use of the B-29 impossible.
When I told Arnold there was a chance that we might not be able to fit the bomb into the B-29, no matter how hard we tried, he asked me what I would do then. I said that if the B-29 could not be used, we would have to consider the use of a British plane, the Lancaster, which I was sure the Prime Minister would be glad to make available to us.
This brought from him the characteristic reply that I had hoped and expected to hear: that he wanted an American plane to deliver our bomb, and that the Air Force would make every effort to ensure that we had a B-29 capable of doing the job. Because the use of a British plane would have caused us many difficulties and delays, I, too, was most anxious to use the B-29 if it could be done. Fortunately, as time went on, we were able to make changes in the design of both types of bombs, so that it became possible to fit them into a specially modified B-29.
Arnold and I agreed that the Air Force would have three major responsibilities: First, it must be able to provide planes able to carry the bombs. These planes would have to have sufficient weight-carrying capacity, adequate bomb bay dimensions, large enough bomb doors and the necessary range. Second, a highly competent tactical unit must be organized, equipped and trained by the time we were able to produce enough fissionable material for a bomb. Third, the bomb must be delivered without fail upon the target.
In addition we would need Air Force assistance in the ballistic tests of the bombs, and special air transportation to move materials and equipment, particularly in the final stages of our preparations for the actual bomb drop.
Both to avoid bothering Arnold with the many details of our joint effort and because he was frequently absent from the country for extended periods, I asked him to appoint an officer with whom we could deal. He designated Major General Oliver P. Echols as our liaison, and emphasized to him that the Air Force must do everything necessary to ensure the success of the mission. Echols named Colonel Roscoe C. Wilson to serve as his alternate, and it was with him that we conducted most of our business. He was a most fortunate choice, for his personality and professional competence ensured the smooth co-operation essential to our success. Through his efforts, the necessary air support was always provided by the subordinate Air Force commands, if not willingly, at least without delay.
While I can say the same of every other Air Force officer with whom I had any dealings in the project, I have always felt particularly grateful to Wilson, for he had to bear the brunt of all our many minor problems with the Air Force as well as a major responsibility for a number of our principal activities. I am sure that he must have had many difficult moments with his Air Force colleagues, as he denied them, for security reasons, information they considered essential to understand the reasons for his requests.
On the more difficult problems, our discussions were often with both Echols and Wilson. Only on very major problems did I feel that it was necessary to see Arnold; however, as with the Secretary of War and General Marshall, I always saw him without delay whenever I felt it was desirable.
In August of 1944, I notified Wilson that the Air Force should initiate planning along the following general lines:
These dates were the earliest by which the Air Force would have to be ready.2
On the basis of this information, Wilson developed a general plan for Air Force support to the project:
The effects of General Arnold’s wholehearted co-operation became very evident when elements of the Air Force appeared reluctant to furnish the necessary number of B-29’s. Their reaction was quite understandable, for these planes were in such short supply that it was impossible to give the crews that were to operate them overseas even the desired minimum of training.
After exploring the situation, Wilson told me that the only way we could get the planes was for me to go see Arnold myself. Even then, in his judgment, we would not get them until shortly before the actual operation.
General Arnold did not hesitate. He fell in with my request almost without discussion, without any evidence of disinclination, and without any suggestion that I might get along with a smaller number. This was typical of all my experiences in dealing with him. He fully realized the importance of the project and never expressed the slightest doubt of our ultimate success.
As I left Arnold’s office to walk down to Wilson’s to tell him how I had made out, he met me in the hall and said that Arnold had just telephoned him. When he added that he was completely surprised and quite impressed by Arnold’s prompt agreement, I replied that I was not the least bit surprised; it was just what I had expected.
Not only did Arnold’s action in this case provide us with the planes we so urgently needed, but it indelibly impressed upon all his staff that MED requests were to be granted without argument. This stood us in good stead until a few months before our actual operations against the Japanese began, when Parsons reported that he did not think our planes were in the best operating condition, and said they should be replaced by new ones. Investigation showed that he was right, but again Wilson felt it would be impossible to do much about it because of the tremendous demands for B-29’s in the Pacific Theater.
When I appealed to Arnold, however, his response again was quick and emphatic. He said that in view of the vast national effort that had gone into the Manhattan Project, no slip-up on the part of the Air Force was going to be responsible for a failure. He then asked me how many new planes I needed, and I replied that as a minimum I would need one to carry the bomb. While several more to carry instruments and make observations would be desirable, they were not essential. I made it clear, however, that no matter what else might suffer, we must have one plane that would be in absolutely perfect working condition when we were ready for the final take-off. Immediately Arnold said that he would order fourteen new planes for us, and fourteen more to be placed in reserve to meet emergency needs. He repeated that no matter what else might go wrong, no one would ever be able to say that the Air Force did not do its utmost to support the Manhattan Project. In this, he was entirely correct.
The new lot of B-29’s was delivered to Wendover Field, Utah, during the spring of 1945. These planes had fuel injection engines, electrically controlled reversible propellers, and were generally much better than their predecessors, particularly from the standpoint of ruggedness.
General Arnold and I had agreed at our first meeting that for the job at hand we should create an Air Force unit that would be self-sustaining; for that reason, Arnold decided to organize it as a composite group, built around a heavy bombardment squadron.
Our first problem was the selection of its commanding officer. In our discussions it was understood from the start that the responsibility for organizing, manning, equipping and training the unit would be Arnold’s; nevertheless, this in no way relieved me of my responsibility to be certain that the group was properly prepared for its mission. Arnold, of course, was as vitally concerned as I was with obtaining for it people of the highest quality, and he could make the selection better than I. I never had the slightest doubt that he would choose as commanding officer the best person available, and in Colonel Paul W. Tibbets he did. Tibbets had been the Operations Officer of the 97th Bombardment Group in the North African and European Theater of Operations, where he had flown the usual number of combat missions, and had then been returned to the United States. Since his return, he had been engaged in testing the B-29 and in formulating the instructions for its use in combat. He was a superb pilot of heavy planes, with years of military flying experience, and was probably as familiar with the B-29 as anyone in the service.
In selecting the other officers of the group a serious mistake was made—one for which I have since regretted my own lack of foresight.
Insofar as possible the group’s officers should have been men who might reasonably be expected to remain in the regular service after the war. We should have recognized the importance of this but, as far as I know, nobody did. Although this mistake made no difference in the accomplishment of our immediate goal, in the postwar years it has been most unfortunate that we have not had in the regular service as many men as possible who were experienced in the use of atomic bombs in actual war. Indeed, sixteen years after Hiroshima and Nagasaki, only four—Tibbets and Ashworth, a weaponeer, and the two bombardiers, Ferebee and Beahan—remain on active duty.
In September, 1944, the 393rd Heavy Bombardment Squadron was detached from the 504th Bombardment Group to form the nucleus of the new unit—the 509th Composite Group.3 The 393rd was picked because of the fine reputation it had gained during its training. The squadron was about to go overseas with its parent organization when the new orders were received, and the unit soon found itself at Wendover Field, Utah, on the Nevada border, about a hundred miles from Salt Lake City.
We chose Wendover as the home station for a number of reasons. It was close enough to Los Alamos by air for proper liaison. It was only a short distance by air from the Salton Sea area, where many of our ballistic tests were to be conducted with dummy bombs. It was located in a sparsely populated area, well removed from centers of population, which simplified security problems. The existing facilities at Wendover were sufficient for our needs, so no new construction would be required. Finally, we could take it over immediately without unduly upsetting any other Air Force operations.
The total authorized strength of the 509th Group was set at 225 officers and 1,542 enlisted men. It was a completely self-contained unit, including besides its Heavy Bombardment Squadron, a Troop Carrier Squadron and all other essential supporting units.
Later, the First Ordnance Squadron Special, Aviation, was activated. This unit consisted of skilled welders, machinists and explosives workers. They had been hand-picked with considerable care from the entire Army Air Force, with a few specialists coming from the ground forces.
In September, after it became clear that we would use both a gun-assembly bomb (the Little Boy) and an implosion bomb (the Fat Man),4 we decided to freeze the external shapes of the three models then existent—one Little Boy and two Fat Men. This was to permit completion of the necessary modifications to the B-29 so that the training of the 509th would not be delayed. The first planes were ready in October and were delivered to Colonel Tibbets at the Wendover Army Air Base, which went under the code name of “Kingman” and sometimes “W-47.” The ballistic tests were begun that same month and were continued until August 8, 1945, by which time each of the two models finally adopted had been dropped in combat.
Throughout its operations at Wendover the 509th was assisted by a special base unit. This included a reserve pool of ordnance personnel and flight test specialists to help in conducting the extensive tests of the components of the bombs and of the full-sized dummy bombs.
In December, the 393rd Squadron was sent to Batista Field, Cuba, for two months of special training in long over-water flights. The program also included training in high-altitude visual and radar bombing. On these practice missions, formation flights were habitually avoided and the crews grew accustomed to operating singly. This was not because we anticipated sending unescorted single planes against Japan, but rather because we were not sure that the escort planes would accompany the bomb-carrying plane all the way from its take-off to the target and back; therefore, we wanted it to be fully capable of independent navigation.
This special training proved very fortunate indeed when later General Curtis LeMay adopted the plan of using a single plane for each bombing mission. This placed all navigational responsibility on the navigator of that plane and was completely at variance with the standard Air Force navigational procedures. Normally, bomber missions were flown by massive formations, with the lead plane carrying a thoroughly competent navigator. The navigators in the other planes were not as a rule nearly so experienced. Fortunately, because of our insistence upon a high state of navigational training throughout the 393rd Squadron, the 509th Group was not caught short when LeMay’s proposal was put into effect.
After the 393rd Bombing Squadron returned to Wendover from the Caribbean, its training continued, and the fliers gained much valuable experience in the course of the ballistic testing of dummy bombs similar in dimensions and weight to the atomic bombs that were eventually used. At first the dummies were inert; later some were filled with normal high explosives. They were never, of course, loaded with any fissionable material. Most of our ballistic testing was conducted at a range in the Salton Sea area. Out of these tests came the information we needed to aim the final bombs accurately.
At the same time, under the supervision of Commander F. L. Ash-worth, Parsons’ assistant at Los Alamos, a long series of tests of the three bomb models was being conducted in order to obtain ballistic data and to determine the best procedures for dropping the bomb. The tests also provided valuable experience in designing and assembling some of the subunits of the weapons.
The Ballistics Group of the Los Alamos Ordnance Division did the research on the problem of aircraft safety in delivery. This group was concerned with such matters as the shock pressure that the B-29 could safely withstand, the flight maneuver that would carry the plane the greatest distance away from the burst in the least time, and the use of special shock-bracing for the crew.
Throughout the fall and winter of 1944-45, the Delivery Group at Los Alamos, which later would bear the primary responsibility for developing the facilities and equipment for assembling the atomic bomb at the overseas base, continued its program of design and production of mock bombs. During this period the final Fat Man design was adopted, and we were able to discontinue our work on the other Fat Man model. Numerous tests were run on bombs that were generally complete, except for the fissionable material.
As our time schedule became tighter, component designs were necessarily altered as little as possible, though many changes were necessary because of earlier wrong guesses. Emphasis during this period was on correcting faults as they became apparent in the tests. As always, the Little Boy was far ahead of the Fat Man from the point of view of design and development, since the group working on the Little Boy had known almost since the beginning the course to be followed.
A new division, called Alberta, was set up at Los Alamos in March of 1945 to take charge of everything involved in the preparation and delivery of the bomb. The members of Alberta’s Weapons Committee became concerned with the need to start work on a new design for the Fat Man that would be based on our most recent knowledge. They realized, however, that this program could not be allowed to interfere with their main task, which was to get the existing model ready as quickly as possible. The job of redesigning the Fat Man, from a sound engineering point of view, was barely organized by the end of the war. Today a great deal of attention would doubtless be given to this problem and possibly many would argue that the improvements should be completed before the bomb was actually used in combat. I overruled any such idea and insisted that there be no delay in the use of the existing models, which were satisfactory, though they did not have the explosive power that the redesigned Fat Man would have had.
1 This number was not reached.
2 In order to avoid any possible unnecessary delay in the use of the bomb, the dates I gave Wilson were in advance of my actual expectations.
3 The 509th Composite Group was formally activated on December 17, 1944, at Wendover Field. It was assigned to the 315th Bombardment Wing of the Second Air Force. Headquarters of the latter was at Colorado Springs, Colorado.
4 The Little Boy was known variously as the Thin Man, the Skinny One and a number of similar names; the Fat Man was also called the Big Boy, the Round Man, the Big Fellow and the like.