agsoth Test Group (Nuclear) to work directly with major commands in formulating definite plans for the operation. In the months following the receipt of this preliminary book message, Headquarters, Task Group 7.4 was active in the planning stages outlining specific requirements and policies for the participating organizations. Many documents were issued during this planning phase, the following being the most important: Task Group 7.4 Planning Directive published on 17 October 1957; Task Group 7.4 Operations Plan on 6 January 1958; and Headquarters, USAF Movement Directive on 9 January 1958. The Task Group 7.4 Operations Plan, made effective as an Opera= tions Order on 15 March 1958, was to be the directing and guiding document for activities throughout the entire operation. This started the second phase of Operation HARDTACK, that of build-up in the forward area. At this time, all units came under the control of Task Group 7.4 - and the majority of the time, up to the first shot, was spent on practicing and rehearsing for the first event. The nuclear testing for Operation HARDTACK commenced with the firing ofthe first event, YUCCA, on 28 April. The test series itself in- cluded 35 nuclear detonations at Eniwetok, Bikini and Johnston Islands. (See Figure 1). This is the largest nuclear test series yet conducted by the United States. Aircraft operated by or under the operational control of Task Group 7.4 participated in every shot fired during HARDTACK. In support of the operation, the aerial support elements carried 60,901 passengers and 2,626,265 pounds of cargo. 10,841 flying“hours from the beginning of the operational phase of 63 APAL/HO These aircraft flew a total of