CHAPTER I THE ORIGINS OF OPERATION CASTLE The roll-up and redeployment of Joint Task Force 132 (JTF 132) after Operation IVY marked the successful conclusion of the fourth series of atomic tests to be conducted in the Marshall Islands. Each of these series—-CROSSROADS, SANDSTONE, GREENHOUSE, and IvY-has generated valuable data from which significant progress in the military application of atomic energy has been possible. The latter of these tests--Operation IVY--witnessed the detonation of a device which marked the furthest advance as of that date (Fall, 1952) in a relatively new direction for military uses of atomic energy. With the large amounts of data acquired during this test, the scientists at Los Alamos Scientific Laboratory as well as those of the newer University of California Radiation Laboratory (UCRL) at Livermore, California, continued in the urgent efforts to perfect the plans and designs of those weapons and devices scheduled for experimental testing in the soon forthcaning CASTLE operation, Organizationally, the Task Force which had conducted Opera- tion IVY was typical of those conducting earlier overseas atomic operations in that it had been administered from a joint headquarters and was composed not only of military personnel but of personnel from the Atomic Energy Commission (AEC) and its varied contractors, Specifically, JTF 132 was organized internally into