NEWSLETTER -NOVEMBER 1998

Former society committee member Louis Wildenboer explained that the two bombs dropped were the end product result of a long, confused and extremely expensive process. Building on the earlier discoveries of French scientists Henri Becquerel and Pierre and Marie Curie, and New Zealander Ernest Rutherford, Germany's Niels Bohr established that the atom was composed of particles that could be separated. In 1930 the German Otto Hahn split the uranium atom and showed that energy could be released in accordance with Albert Einstein's formula that energy equals mass times the velocity of light squared. To release energy in the form of an explosion the type of uranium required was U235, which had to be separated from ordinary uranium by physical means and in minute amounts.

In 1940 the American chemist Glen Seaborg discovered that an element now known as plutonium could also be extracted from uranium in small quantities, but by chemical means. The bombs exploded over Hiroshima and Nagasaki were manufactured from U235 and plutonium respectively. The first employed a conventional explosive to fire one lump of U235 into another to make up a critical mass that would explode. The second, the implosion method, consisted of surrounding a hollow sphere of plutonium with conventional explosives to compress it into a critical mass. Each method required its own manufacturing process.

The Manhattan project, as it came to be called. was set in motion by President Roosevelt after a letter from Einstein warning him that the Germans were already working on the theory of the bomb.

A hard-driving army brigadier named Richard Groves, a scientist in his own right, was put in charge of organising the project, while the scientific side was handled by Dr Robert Oppenheimer, a brilliant physicist from the University of California at Berkeley. The two assembled a corps of eminent scientists, and virtually imprisoned them in a newly built experimental facility at Los Alamos, a remote spot in the Nevada desert.

To separate the required U235 and plutonium from uranium, two massive manufacturing plants were built, one employing 82 000 people, the other 50 000. Altogether 600 000 people worked on producing the bombs, and only the top men knew what it was all about. The Manhattan project cost a total of around $2,5 billion, an astronomical sum in those days, and it all came together at 05h00 on 6th July 1945 when the first bomb, using plutonium, was successfully exploded. The results surpassed all expectations. On 26th July the second batch of bomb material, this time U235, was shipped with all haste to Tinian Island near Saipan, from where it was dropped on Hiroshima 11 days later. Three days afterwards, Nagasaki was hit with the plutonium bomb, and the greatest war in history was over.

Meanwhile, the war in the Pacific was becoming increasingly bloody as allied forces closed in on Japan, and as Japanese resistance became more suicidal. There was little public sympathy for Japan, whose atrocities towards the inhabitants of the territories it had occupied during its drive for empire had contravened all western concepts of how a civilised nation should behave. Conservative estimates held the Japanese responsible for the deaths of at least 17 million civilians and POWs between 1931 and 1945, with 10 million occurring between December 1941 and August 1945. By that month it looked as if the planned invasion of the Japanese mainland would be defended to the last man.

Truman was told by his military advisers that the number of Japanese troops concentrated in the island of Kyushu, the first US objective, had been increased to 945 000 and that the estimated casualties likely to be suffered by an invading force would be around 100 000 dead and about 300 000 wounded. In addition, the naval forces could expect another 50 000 dead and nearly the same number wounded. These estimates, based on the experience of previous amphibian actions, were hugely increased from the ones presented to Truman only the month before. Moreover, they did not include figures for the casualties likely to be incurred in operation Coronet, the proposed invasion of Honshu, and among Japanese civilians, who had already sustained 100 000 dead and around one million injured in the fire-bombing of Tokyo the previous March.

The Japanese were given their ultimatum to surrender in the Potsdam Declaration of August 1945, and they returned an ambiguous answer. The first bomb, the uranium one, hit the garrison town and industrial centre of Hiroshima on 6th August, leaving 71 000 dead and around 68 000 injured, 18 000 of them seriously. The Japanese War Minister decided there was only one bomb and thus nothing more to fear. This complacency was shattered on the same day when the second bomb, the plutonium one, hit Nagasaki. Even then the Japanese military wished to continue the war, and when the Emperor stepped in and ordered acceptance of the Potsdam Declaration an attempt was made to seize the recording of his speech to the nation. This was finally broadcast on 15th August, and the third and subsequent bombs being made ready were never dropped..