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mentation was meagre. The test was carried out 

 during wartime with emphasis on secrecy and the 

 rapid development of a bomb for use in bringing 

 to an end a war that had already cost the lives 

 of millions. Alamogordo represented a proving 

 ground, not an elaborately instrumented experi- 

 ment. As a source of scientific data concerning 

 the bomb it left much to be desired. 



The subsequent uses of the bomb at Hiroshima 

 and Nagasaki were carried out under combat con- 

 ditions. They, too, were of little significance from 

 a technical point of view. They did provide data 

 concerning the effect of the bomb on a city of 

 the Japanese type; but this data was entirely in 

 the form of rough estimates proving little. 



Bomb vs Ships 



TO many this question arose: What ettect would 

 an atomic bomb have on a fleet of naval ves- 

 sels? Much thought had been given to this ques- 

 tion during the development phases of the bomb. 

 As early as 1944 the Manhattan Engineer District, 

 charged with development of the bomb, had given 

 serious consideration to the possibility of "testing" 

 one of its atomic bombs against the Japanese 

 Navy at Truk Island. And just after the surrender 

 of Japan Senator Brien McMahon of Connecticut 

 made a speech in the Senate in which he advo- 

 cated the use of the atomic bomb against the 

 captured Japanese fleet. 



Speculation on this subject followed diverse 

 lines. What amount and type of damage would 

 the bombs produce in the first instance? To what 

 extent should accepted principles of ship design 

 be altered in future construction? What defensive 

 measures could be taken by a ship attacked with 

 atomic missiles? Were traditional tactical prac- 

 tices outmoded? 



Joint Task Force ONE 



TO answer questions like these the Joint Chiefs 

 ' of Staff, with Presidential approval obtained 

 on January 10, 1946, created Joint Task Force 

 ONE; its mission: to carry out the atomic bomb- 

 ing of a target array of naval ships. Vice Admiral 

 W. H. P. Blandy was designated Commander. This 

 Task Force comprised a total of more than 200 

 ships, 42,000 men, and 150 aircraft. It included 

 members of the Navy, Army Air and Ground 

 Forces, and civilian scientists. Its directive ordered 

 one test of the bomb in air above the target fleet, 



and a second detonation in the water, slightly be- 

 low the surface. 



Two tests were necessary. The air and subsur- 

 face bursts constituted quite different test situa- 

 tions. This difference can be quickly told. When 

 exploded in air at low altitude, as in Test "Able," 

 an atomic bomb subjects everything in its vicinity 

 to violent air-blast and intense radioactivity. Much 

 of the radioactivity is dissipated into the upper 

 atmosphere in the so-called "mushroom cloud." 

 Ships subjected to the bomb were expected to re- 

 ceive, and did receive a severe air blast or con- 

 cussion. Crews on the test ships, had there been 

 any, would undoubtedly have suffered many cas- 

 ualties from the lethal radioactivity. 



Test "Baker," the underwater shot, utilized the 

 bomb's tremendous energy release in a different 

 way. The huge pressure built up by the bomb 

 under the water was transmitted to the under- 

 water portions of the neighboring ships. Ship 

 hulls were by this pressure forced inward on all 

 sides at once. Furthermore, since the bomb was 

 submerged in the lagoon, its radioactivity was 

 prevented from passing instantly into the upper 

 atmosphere. Intense and lasting radioactivity was 

 produced in the water of the lagoon. The ships, 

 drenched by tons of water thrown up by the ex- 

 plosion, became similarly contaminated. The ex- 

 tent of such contamination proved a matter of 

 great interest. 



Bikini 



T*HE Bikini Atoll, a typical Pacific Ocean island 

 group in the Marshalls, was chosen as the site 

 of the test. It is 2000 miles southwest of hlawaii, 

 and 4150 miles from San Francisco. Several fac- 

 tors made Bikini an excellent choice. Its size was 

 ideal — an atoll of several small islands surrounding 

 a lagoon 20 miles long' and 10 miles wide. Aver- 

 age depth of water inside the lagoon was approxi- 

 mately 200 feet, a good anchorage for the target 

 ships. The Atoll is remote from fishing areas, 

 steamer lanes. It is located 250 miles north of 

 Kwajalein, a suitable base from which the bombing 

 plane could operate. Its weather conditions were 

 excellent. 



Preparations 



QLANS for the Operation went forward during 

 ■ the Spring and early summer of 1946. Surveys 

 of the Bikini lagoon were made, its waters combed 

 for truant Japanese mines, its natives evacuated 



