The Alamogordo test 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. We could now establish firmly that the first atomic bomb drop on Japan would be sometime around the first of August.
The major portion of the U-2 35 component for this bomb began its journey overseas on July 14 when a convoy consisting of a closed black truck, accompanied by seven cars with security agents, left Santa Fe for Albuquerque. From Albuquerque, the bomb was flown in an Air Force plane to Hamilton Field just outside San Francisco, where it was picked up and carried to Hunter’s Point. The parts of the bomb, which were packed in a large crate and a small metal cylinder, were in the custody of Major Furman from my office, and Captain Nolan, a radiologist at the Los Alamos Base hospital.
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 only untoward incident during the voyage grew out of the fact that Furman and Nolan were traveling in the guise of field artillerymen, which led to some very searching and embarrassing questions by the ship’s gunnery officers, which they were wholly unprepared to answer.
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.
In looking back at this phase of the operation, I can only feel intense relief that our cargo was safely delivered to its destination, for, as we later learned, the Indianapolis was a very poor choice to carry the bomb. She had no underwater sound equipment, and was so designed that a single torpedo was able to sink her quickly.
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.”
A few days later he told me, “I just had one of my senior staff officers in here telling me about that operation of yours using two C-54’s to carry a few hundred pounds of cargo. The mildest words he used were ‘unreasonable’ and ‘idiotic’ I finally told him that we would continue to furnish whatever the MED asked for and that he didn’t have to say any more.” I never asked George how much Arnold had told him but he always gave us the utmost in co-operation.
One of our security officers at Los Alamos, who rode one of the planes, Second Lieutenant R. A. Taylor, Jr., told me later of his trip to Tinian. He was responsible for a box about the size of two orange crates which contained certain assembly parts for the bomb. The other plane carried Lieutenant Colonel Peer de Silva, the head of security at Los Alamos, with the final small key component of U-235 for the bomb. En route to San Francisco (Hamilton Field), the first stop, the two planes were to keep in close contact and if de Silva’s plane went down the other was to spot the point and circle until help came.
When the cargo arrived at Albuquerque for loading it was under heavy armed guard. The two plane crews were flabbergasted when they saw the small boxes that were to comprise the entire freight.
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.
De Silva had been instructed previously on what to do if any essential request were refused. He was to say that his was a highly secret mission under General Marshall’s direct personal control and that, if there was any doubt, a telephone call should be made directly to General Marshall for verification. I was sure that no one would be likely to make such a check, and, if by chance someone did, I hoped that General Marshall’s office would spot it as part of my operations and ask me about it.
This procedure was used only on rare occasions during the entire project. It invariably stopped all further argument.
Our basic operational plans were to launch the atomic attack using the gun-type bomb as soon as the final bit of U-235 reached Tinian by air and weather permitted. As soon as possible after this, a second attack would be initiated. This time an implosion-type bomb would be dropped. The controlling factor on the second bomb was the date by which a sufficient amount of plutonium could be processed and delivered to Tinian. After that, all that was needed was suitable weather.
Soon after my return from Alamogordo, I had learned that General Spaatz was in town making preparations to go to the Pacific where he was to take field command of the 20th Air Force. I got hold of him and together we went over the situation. He quickly agreed with and confirmed all the arrangements I had previously made with LeMay.
On July 23, I prepared the final written directive for the coming operations out of Tinian. It read as follows:
To General Carl Spaatz, CG, USASTAF:
Signed: T. T. Handy1
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.
On July 24, I sent a memorandum to General Marshall at Potsdam to obtain his final approval of our plan of operation. It was about two pages long. Attached to it were a small map of Japan and near-by Asia (cut from a large National Geographic map); a one-page description of each of the four targets (Hiroshima, Nagasaki, Kokura, and Niigata); a one-page draft of a necessary action by the Joint Chiefs releasing the previously reserved targets (all but Nagasaki, which had never been reserved) to the Commanding General, Army Air Forces, for attack only by the 509th Group, 20th Air Force; and a copy of a tentative draft of a directive to Spaatz. This apparently made no mention of Nagasaki.2 That particular target had only recently been added in place of Kyoto and in some way I must have failed to list it in the enclosure. The cabled draft that was sent later for his definite approval did include it.
The memorandum gave the probable date of the first bombing as between the first and tenth of August. It was to be as soon after the first as the Little Boy could be assembled, and the weather permitted visual bombing. We expected that this would be about August 3, but it depended upon how soon we would have the final amount of U-235.
The memorandum stated that there would be officers in each bombing plane whose familiarity with the design, development and technical features of the bomb would qualify them to render final judgment if any emergency required a deviation from the plan. The Senior Technical Officer on the first flight would be Captain Parsons of the Navy.
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.
I went on to forecast our delivery rates after the third bomb, and to say that all bombs would be delivered by the 509th Composite Group on targets having high priorities at the time of delivery. I added that all instructions concerning the targets would be issued through the Commanding General, U.S. Army Air Forces. This was in accord with the policy agreed to by Arnold and me some months previously that control over the weapons’ use would remain in Washington during the foreseeable future.
My statement that all instructions would be issued through the Commanding General, USAAF, was also a clear indication to General Marshall that the orders for our operations against Japan would originate with me, be approved by him, and be issued to Spaatz over Arnold’s signature.
In two brief paragraphs, I gave the organization for the coming operation:
Major General L. R. Groves has overall direction of the atomic fission bomb project. Brigadier General T. F. Farrell, General Groves’ Deputy, and Rear Admiral W. R. Purnell, the Navy member of the Military Policy Committee, will be at the base prior to the first mission to co-ordinate the project with Army and Navy Commanders in the theater.
The Air Forces operations will be under the command of General Spaatz, Commanding U. S. Army Strategic Air Forces. The 20th Air Force is under the command of Major General LeMay,3 The 509th Composite Group is under the command of Colonel Paul Tibbets.
General Marshall’s approval of this plan put our operation fully into motion.
On July 31 (July 30 in Washington), Farrell sent me a rather lengthy cable. He had arrived at Guam the day before and had had a meeting with LeMay that afternoon. His cable included this sentence: “1 August is interpreted by LeMay and Farrell as coming within the intent of the directive.” He said that the bomb could be ready 2300 E.W.T., 31 July, and added: “LeMay needs 11 hours more which would be 1 August, 1000 E.W.T.” I have been unable to find any trace of a reply to this cable in which I either confirmed or objected to the LeMay-Farrell interpretation.
If I did not reply, it was an error, for I should have done so in order to avoid any possible misunderstanding that might cause a delay. The fact that I fully agreed with their interpretation makes no difference. If the cable had said July 30, I would have reacted sharply and at once. I knew from Secretary Stimson that President Truman wanted to be sure that Japan had enough time to answer the Potsdam ultimatum. I had told Mr. Stimson before his departure that we did not expect to be ready until July 31, and we both understood that unless I received orders to the contrary, we would wait for that date even if unexpectedly we should be ready a day or two sooner. The difference in dates between Japan and Washington was overlooked in all of our arrangements. It should not have been; I should have caught the omission.
It was, and always had been, my understanding that our target date was the first of August, and I was surprised in rereading the official order recently to find mention of August 3. I am sure I had no reason for using this date rather than August 1, except that at the time the order was actually signed by General Handy we did not think we could deliver the bomb before that date.
This surmise is fully supported by the wording of my August 6 report to General Marshall on the bombing of Hiroshima. It opened with the sentence: “The gun type bomb was ready at Tinian on 31 July awaiting first favorable weather.” This report went on to say that originally we had expected that the first favorable weather would be on August 3, but that in fact it was not until the sixth that the bomb could be used.
Several writers have attempted to read hidden meanings into the date of August 3. In doing this, they have ignored entirely the actual wording of the order which was, “After about 3 August.” They have also ignored the fact that the word “about” is thoroughly understood in the American Army. Official travel regulations of that period even defined “about” as normally including a period of four days before and four days after the specific date cited.
Everyone concerned understood this, and Farrell’s cable was sent only because of his desire to be certain that there could be no misunderstanding. Even then he did not put it as a query, but as a statement of his and LeMay’s understanding.
Soon after Farrell’s arrival in Guam, and after the bomb components were ready, while we were waiting only for favorable weather, Spaatz sent a cable reminding us of the reported location of POW camps in and near the target areas. He asked whether the locations of these camps would upset his orders, particularly with respect to the selection of targets. There were no POW camps listed in the vicinity of Hiroshima, although there was one reported about a mile outside of Nagasaki, which was supposed to contain several hundred Allied POW’s.
Handy received the message and turned it over to me. As I studied it, I was bothered by the fact that the intelligence estimate that both Spaatz and we were using was apparently incorrect in its details. If it was correct, the camp was on the west side of Nagasaki Bay; yet it seemed much more likely that it would be on the other side, which was much closer to the docks where it was believed that the prisoners were being worked. No matter which location was right, however, it did seem likely that at the probable time of an explosion POW’s would be working in the dock area and would be fully exposed to the expected hazards.
Spaatz’ query was not an easy one to answer. I am sure he would not have sent it if the control of the operation had not been so closely held in Washington, for it involved a decision that normally would have been made by the commander in the field. Handy felt that the decision should be made by the Secretary of War, but later agreed with me that we should tell Spaatz to disregard the reported camps; however, we decided that I would show the Secretary the outgoing cable before sending it. This would free him of the burden of making the decision, as I felt we should, since the burden was my own. At the same time he would have an opportunity, if he chose to take advantage of it, to overrule us before any harm was done. A cable was therefore prepared, telling Spaatz that there was no change in the targets because of the POW situation; that he could, however, adjust the aiming points, which were already his responsibility, in such a way as to decrease the possibility of hitting any POW camp.
I took the cable in to Mr. Stimson, as well as the one we had received from Spaatz, and said I was showing them to him for his information. I added that this was our responsibility and we were not passing it on to him. I did not emphasize that he could change it if he wished, though I told him that I was sending it as soon as I left his office. His only reaction was to thank me for showing him the cable before it was sent.
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. It was provided further that they had to be specifically authorized by me or by General Farrell in the case of personnel not permanently assigned to the 509th Group, and by the Commanding General, U.S. Army Strategic Air Forces, or a senior officer designated by him, in the case of permanent group personnel. These authorizations had to be specifically contained in official written orders. Without such waivers we would have been seriously handicapped, not only in the bomb-carrying plane, but in the instrument plane and the observation plane as well.
1 General Handy was Acting Chief of Staff during General Marshall’s absence in Potsdam.
2 The original was destroyed in Potsdam (to avoid any chance of breach of security). A copy, possibly made afterward, in my files omitted Nagasaki in the directive.
3 LeMay became Chief of Staff under Spaatz on August 2, 1945.