such time as the Air Task Group was reactivated for REDWING, ARDC was requested to assist in the planning for any future overseas tests. This planning was to. be conducted under the direction of, and in conjunction with, Headquarters, JTF SEVEN. All personnel previously assigned to Task Group 7.4 were reassigned to various staff sections within the Air Force Special Weapons Center or to its subordinates, The various staff sections of AFSWC were made responsible for planning or other actions regarding the Air Task Group in the next overseas tests. C. A COMPARISON BETWEEN IVY AND CASTLE CASTLE was a vastly more complex and ‘difficult operation than IVY. i Operation IVY, the 1952 test series, had been a two-shot affair, covering a two-month operational period. The Air Task Group was based on Kwajalein, approximately 290 nautical miles from the shot areas in the northern reaches of Eniwetok Atoll. KING Shot on IVY was an air drop from a modified B-36 of (a oc: Shot, for which all personriel in Eniwetok Atoll had been evacuated, was the world's first megaton device. In contrast, CASTLE was a six-shot operation, involving no air drops, but five of the devices detonated were in the megaton range, making extremely careful preparation necessary. The operational period cov— ered nearly five months and was lengthened by almost daily postponements of five of the shots because high winds in the upper atmosphere would have placed several Pacific areas in danger of almost certain radioac- tive fall-out. Five shots were fired in Bikini Atoll and one shot, a megaton device, was detonated in Eniwetok Atoll, location of Task Group 7.4. AFWUHO [13