bombing of civilian populations.” As war approached, revulsion began to give way to impulses of revenge; in the summer of 1939 Herbert Hoover could urge an international ban on the bombing of cities and still argue that “one of the impelling reasons for the unceasing building of bombing planes is to prepare reprisals.” Bombing was bad because it was enemy bombing.
So although Roosevelt had asked Congress for increased funds for long-range bombers nine months before, in appealing to the belligerents on September 1, 1939, he could still articulate the moral indignation of millions of Americans:
The ruthless bombing from the air of civilians in unfortified centers of population during the course of the hostilities which have raged in various quarters of the earth during the past few years, which has resulted in the maiming and in the death of thousands of defenseless men, women and children, has sickened the hearts of every civilized man and woman, and has profoundly shocked the conscience of humanity.
If resort is had to this form of inhuman barbarism during the period of the tragic conflagration with which the world is now confronted, hundreds of thousands of innocent human beings who have no responsibility for, and who are not even remotely participating in, the hostilities which have now broken out, will lose their lives. I am therefore addressing this urgent appeal to every Government which may be engaged in hostilities publicly to affirm its determination that its armed forces shall in no event, and under no circumstances, undertake the bombardment from the air of civilian populations or of unfortified cities, upon the understanding that these same rules of warfare will be scrupulously observed by all of their opponents. I request an immediate reply.
Great Britain agreed to the President's terms the same day. Germany, busy bombing Warsaw, concurred on September 18.
The invasion of Poland brought Britain and France into the war on September 3. Abruptly Roosevelt's schedule filled to overflowing. In early September in particular he was working overtime with a reluctant Congress to revise the Neutrality Act to terms more favorable to Britain; Sachs was unable even to discuss arranging an interview until after the first week in September.
By September Kurt Diebner's new War Office department had consolidated German fission research under its authority. Diebner enlisted a young Leipzig theoretician named Erich Bagge and together the two physicists planned a secret conference to consider the feasibility of a weapons project. They had the authority to enlist the services of any German citizen they wished and they used it, sending out papers that left Hans Geiger, Walther Bothe, Otto Hahn and a number of other exceptional older men nervously uncertain if they were being invited to Berlin for consultation or ordered to active military service.
At the conference in Berlin on September 16 the physicists learned that German intelligence had discovered the beginnings of uranium research abroad — meaning, presumably, in the United States and Britain. They discussed the long, thorough theoretical paper by Niels Bohr and John Wheeler, “The mechanism of nuclear fission,” that had been published in the September
Heisenberg therefore attended a second Berlin conference on September 26 and discussed two possible ways to harness the energy from fission: by slowing secondary neutrons with a moderator to make a “uranium burner” and by separating U235 to make an explosive. Paul Harteck, the Hamburg physicist who had written the War Office the previous April, traveled to the second conference armed with a paper he had just finished on the importance of layering uranium and moderator to avoid the U238 capture resonance — the same insight that had come independently to Fermi and Szilard in early July. Harteck's study, however, considered using heavy water as moderator, even though Harteck had worked with Rutherford at the Cavendish and knew from personal experience how expensive heavy-water production could be — water in which deuterium replaced hydrogen had to be tediously distilled from tons of ordinary H2O.
Diebner and Bagge had outlined for the second conference a “Preparatory Working Plan for Initiating Experiments on the Exploitation of Nuclear Fission.” Heisenberg would head up theoretical investigation. Bagge would measure deuterium's cross section for collision to establish how effectively heavy water might slow secondary neutrons. Harteck would look into isotope separation. Others would experiment to determine other significant nuclear constants. The War Office would take over the Kaiser Wilhelm Institute of Physics, finished in 1937 and beautifully equipped. Adequate funds would be forthcoming.
The German atomic bomb project was well begun.
It may have been no less complicated by humanitarian ambiguities than the project the Hungarians in the United States proposed. One young but highly respected German physicist involved in the work from near the beginning was Carl Friedrich von Weizsacker, the son of the German Undersecretary of State. In a 1978 memoir von Weizsacker remembers discussing the possibility of a bomb with Otto Hahn in the spring of 1939. Hahn opposed secrecy then partly on the grounds of scientific ethics but also partly because he “felt that if it were to be made, it would be worst for the entire world, even for Germany, if Hitler were to be the only one to have it.” Like Szilard, Teller and Wigner, von Weizsacker remembers realizing in discussions with a friend “that this discovery could not fail to radically change the political structure of the world”:
To a person finding himself at the beginning of an era, its simple fundamental structures may become visible like a distant landscape in the flash of a single stroke of lightning. But the path toward them in the dark is long and confusing. At that time [i.e., 1939] we were faced with a very simple logic. Wars waged with atom bombs as regularly recurring events, that is to say, nuclear wars as institutions, do not seem reconcilable with the survival of the participating nations. But the atom bomb exists. It exists in the minds of some men. According to the historically known logic of armaments and power systems, it will soon make its physical appearance. If that is so, then the participating nations and ultimately mankind itself can only survive if war as an institution is abolished.
Both sides might work from fear of the other. But some on both, sides would be working also paradoxically believing they were preparing a new force that would ultimately bring peace to the world.
As September extended its violence Szilard grew impatient. He had heard nothing from Alexander Sachs. Pursuing Sachs' previous suggestions and his own leads, he arranged for Eugene Wigner to give him a letter of introduction to MIT president Karl T. Compton; recontacted a businessman of possible influence whom he had once interested in the Einstein-Szilard refrigerator pump; read a newspaper account of a Lindbergh speech and reported to Einstein that the aviator “is in fact not our man.” Finally, the last week in September, he and Wigner visited Sachs and found to their dismay that the economist still held Einstein's letter. “He says he has spoken repeatedly with Roosevelt's secretary,” Szilard reported to Einstein on October 3, “and has the impression that Roosevelt is so overburdened that it would be wiser to see him at a later date. He intends to go to Washington this week.” The two Hungarians were ready to start over: “There is a distinct possibility that Sachs will be of no use to us. If this is the case, we must put the matter in someone else's hands. Wigner and I have decided to accord Sachs ten days' grace. Then I will write you again to let you know how matters stand.”
But Alexander Sachs did indeed travel to Washington, not that week but the next, and on Wednesday, October 11, presented himself, probably in the late afternoon, at the White House. Roosevelt's aide, General Edwin M. Watson, “Pa” to Roosevelt and his intimates, sitting with his own executive secretary and military aide, reviewed Sachs' agenda. When he was convinced that the information was worth the President's time, Watson let Sachs into the Oval Office.
“Alex,” Roosevelt hailed him, “what are you up to?”
Sachs liked to warm up the President with jokes. His sense of humor tended to learned parables. Now he told Roosevelt the story of the young American inventor who wrote a letter to Napoleon. The inventor proposed to build the emperor a fleet of ships that carried no sail but could attack England in any weather. He had it in his power to deliver Napoleon's armies to England in a few hours without fear of wind or storm, he wrote, and he was
