crash initiating a high order [i.e., nuclear] explosion are… sufficiently small [as to be] a justifiable risk.” Fat Man could even survive jettisoning into shallow water. Little Boy was less forgiving. Since the gun bomb contained more than two critical masses of U235, seawater leaking into its casing could moderate stray neutrons sufficiently to initiate a destructive slow-neutron chain reaction. The alternative, jettisoning Little Boy onto land, might loose the U235 bullet down the barrel into the target core and set off a nuclear explosion. For temperamental Little Boy, the minutes note, unluckily for the aircrew, “the best emergency procedure that has so far been proposed is… the removal of the gun powder from the gun and the execution of a crash landing.”
Target selection had advanced. The committee had refined its qualifications to three: “important targets in a large urban area of more than three miles diameter” that were “capable of being damaged effectively by blast” and were “likely to be unattacked by next August.” The Air Force had agreed to reserve five such targets for atomic bombing. These included:
(1)
(2)
The other three targets proposed were Yokohama, Kokura Arsenal and Niigata. An unsung enthusiast on the committee suggested a spectacular sixth target for consideration, but wiser heads prevailed: “The possibility of bombing the Emperor's palace was discussed. It was agreed that we should not recommend it but that any action for this bombing should come from authorities on military policy.”
So the Target Committee sitting in Oppenheimer's office at Los Alamos under the modified Lincoln quotation that Oppenheimer had posted on the wall — this world cannot endure half slave and half free — remanded four targets to further study: Kyoto, Hiroshima, Yokohama and Kokura Arsenal.
The committee and its Los Alamos consultants were not unmindful of the radiation effects of the atomic bomb — its most significant difference in effect from conventional high explosives — but worried more about radiation danger to American aircrews than to the Japanese. “Dr. Oppenheimer presented a memo he had prepared on the radiological effect of the gadget… The basic recommendations of this memo are (1) for radiological reasons no aircraft should be closer than 2V2 miles to the point of detonation (for blast reasons the distance should be greater) and (2) aircraft must avoid the cloud of radio-active materials.”
Since the expected yields of the bombs under discussion made them something less than city-busters, the Target Committee considered following Little Boy and Fat Man with conventional incendiary raids. Radioactive clouds that might endanger LeMay's follow-up crews worried the targeters, though they thought an incendiary raid delayed one day after an atomic bombing might be safe and “quite effective.”
With a better sense for having visited Los Alamos of the weapons it was targeting, the Target Committee scheduled its next meeting for May 28 at the Pentagon.
Vannevar Bush thought the second Interim Committee meeting on May 14 produced “very frank discussions.” The group, he decided, was “an excellent one.” These judgments he passed along to Conant, who had been unable to attend. Stimson won approval of the Scientific Panel as constituted and discussed the possibility of assembling a similar group of industrialists. As his agenda noted, such a group would “advise of [the] likelihood of other nations repeating what our industry has done” — that is, whether other nations could build the vast, innovative industrial plant necessary to produce atomic bombs.
That May Monday morning the committee received copies of Bush's and Conant's September 30,1944, memorandum to Stimson, the discussion framed on Bohr's ideas of the free exchange of scientific information and inspection not only of laboratories throughout the world but also of military installations. Bush promptly hedged his commitment to so open a world:
I… said that while we made the memorandum very explicit, that it certainly did not indicate that we were irrevocably committed to any definite line of action but rather felt that we ought to express our ideas early in order that there might be discussion as [a] result of which we might indeed change our thoughts as we studied into the subject further, and I said also that we would undoubtedly write the memorandum a little differently today due to the lapse of time since last September.
At the end of the meeting Byrnes took his copy along and studied it with interest.
The Secretary of State-designate was learning fast. When the Interim Committee met again on Friday, May 18, with Groves sitting in, Byrnes brought up the Bush-Conant memorandum as soon as draft press releases announcing the dropping of the first atomic bomb on Japan had been reviewed. It was Bush's turn to be absent; Conant passed along the news:
Mr. Byrnes spent considerable time discussing our memorandum of last fall, which he had read carefully and with which he was much impressed. It apparently stimulated his thinking (which was all that we had originally desired I imagine). He was particularly impressed with our statement that the Russians might catch up in three to four years. This premise was violently opposed by the General [i.e., Groves], who felt that twenty years was a much better figure… The General is basing his long estimate on a very poor view of Russian ability, which I think is a highly unsafe assumption…
There was some discussion about the implications of a time interval as short as four years and various international problems were discussed, particularly the question of whether or not the President should tell the Russians of the existence of the weapon after the July test.
Bohr's proposal to enlist the Soviet Union in discussions before the atomic bomb became a reality here slips to the question of whether or not to tell the Soviets the bare facts after the first bomb had been tested but before the second was dropped on Japan. Byrnes thought the answer to that question might depend on how quickly the USSR could duplicate the American accomplishment. The Interim Committee's recording secretary, 2nd Lieutenant R. Gordon Arneson, remembered after the war of this confrontation that “Mr. Byrnes felt that this point was a very important one.” The veteran of House and Senate cloakrooms was at least as concerned as Henry Stimson to extract a quid pro quo for any exchange of information, as Conant's next comment to Bush demonstrates:
This question [i.e., whether or not to tell the Russians about the atomic bomb before using it on Japan] led to the review of the Quebec Agreement which was shown once more to Mr. Byrnes. He asked the General what we had got in exchange, and the General replied only the arrangements controlling the Belgium-Congo
The Quebec Agreement of 1943 renewed the partnership of the United States and Great Britain in the nuclear enterprise; Groves was justifying it as an exchange for British help in securing the Union Miniere's agreement to sell the two nations all its uranium ore. The British-American relation was built on deeper foundations than that, and Conant moved quickly to limit the damage of Groves' blunder:
Some of us then pointed out the historic background and [that] our connection with England flowed from the original agreement as to the complete exchange of scientific information… I can foresee a great deal of trouble on this front. It was interesting that Mr. Byrnes felt that Congress would be most curious about this phase of the matter.
If Byrnes had begun his service on the Interim Committee respecting the men who had carried the Manhattan Project forward, he must have conceived less respect for them now. Both Stimson and Bush, Conant told Byrnes, had talked to Churchill in Quebec. If, as it seemed, they could be conned by the British into giving away the
