«g OCG Gen Cor TS MP files Fldr 25 P Secret RD Memo Gen Groves for 24 Jul 45 sub Plan of Operations - Atomic Fission Bomb c s 1 First Operation The first gun-type atomic fission bomb should be ready to take off from the base at Tinian between 1 August and 10 August 1945 As soon after the readiness date as the weather is suitable the bomb will be delivered on a target in Japan by a specially modified B-29 airplane of the 509th Composite Group 20th Air Force The explosive effect is now expected to exceed that of 10 000 tons of TNT and can well be as much as 30 000 2 Assembly The bomb will be finally assembled at Tinian by a special technical group of civilian and military scientific personnel from the project 3 Targets At least three targets should be available Hiroshima Kokura and Niigata have been reserved as targets for the first bombs Niigata is the most unfavorable because of its location on the far said of Japan The targets provide sufficient geographical spread to insure as far as possible that weather closure after the take-off of the airplane cannot prevent delivery of the bomb Detailed information on the three targets is shown in Tab A 4 Delivery The first mission will be carried out by visual bombing in daylight and it may be necessary to wait several days after the readiness date for suitable weather The bomb will be dropped from a height not less that 30 000 feet above the ground to avoid possible damage to the airplane from the blast The bombs will be detonated by radar proximity fuses at the heights which should produce the maximum blast damage for the gun type about 2000 feet above the ground The airplane carrying the bomb will be accompanied by two additional B-29 airplanes carrying scientific personnel with the necessary complicated instruments to observe and record the effects of the detonation The observing airplanes will be required to stay several miles away from the point of impact of the bomb No other fix friendly aircraft will be in the immediate vicinity In the airplane carrying the bomb there will be two officers from the project technical group who are qualified by familiarity with the design development and technical features of the bomb to render final judgment in the event that an emergency requires deviation from the tactical plan The senior technical officer on the first flight will be either Captain W S Parsons U S N or his alternate Commander F L Ashworth u s N 5 Official Communiques Dissemination of information concerning the use of the weapon against Japan is reserved to the Secretary of War and the President of the United States No communiques on the subject or releases of information will be issued by Commanders in the field without specific authority 6 Later Operations The first implosion type bomb should be ready at the Tinian base about 6 August but initially there must be a gap of three days between successive bombs of all types The second implosion bomb should be ready 24 August It is planned that they will be delivered in the same manner as the gun type bomb on the targets named above probably excluding the one attacked by the gun type bomb They will be detonated about 1500 feet above the ground It is expected that each will have an effect equal to that of 15 000 tons of TNT r oicLAss1F1Eo • AutboritY qQ3 O 1-5 • l r ----------------- 2 - - - - - - - - - - - Additional bombs will be ready for delivery at an accelerating rate increasing from about three in September to possibly seven in December with a sharp increase in production expected early in 1946 The sharp increase to seven in December is dependent upon the modification of the present implosion bomb which uses plutonium only to one using a combination of plutonium and uranium 235 This appears to be thoroughly sound and to offer no difficulty in production All bombs will be delivered by the 509th Composite Group on targets having a high priority at the time of delivery Instructions concerning such targets will be issued through the Commanding General u s Army Strategic Air Forces 7 Organization Major General L R Groves has overall direction of the atomic fission bomb project Brigadier General T F Farrell General Groves' deputy and Rear Admiral W R Purnell the Navy member of the Military Policy Committee will be at the base prior to the first mission to coordinate the project with Army and Navy Commanders in the theatre The Air Forces operations will be under the command of General Spaatz commanding U s Army Strategic Air Forces The 20th Air Force is under the command of Maje General Curtis Le May The 509th Composite Group is under the command of Colonel Paul Tibbets 8 On my recommendation the Joint Chiefs of Staff recently reserved the three cities from attack by any of our forces pending further isstructions from them 9 It is recommended that you approve the above plan of operations and issue a tentative directive to General Spaatz for action with copies to General MacArthur and Admiral Nimitz for their information Final approval with modifications if desired can be given later A draft of the tentative directive and of a necessary action by the Joint Chiefs of Staff are attached Tabs B and ''C TAB B TENTATIVE Draft of Directive by the Chief of Staff to General Spaatz with copies for information to General MacArthur and Admiral Nimitz x 1 The 509th Composite Group 20th Air Force will deliver its first special bomb as soon as weather will permit visual bombing after about 3 August 1945 on one of the targets Hiroshima Kokura and Niigata in the priority listed To carry military and civilian scientific personnel from the War Department to observe and record the effects of the explosion of the bomb additional aircraft will accompany the airplane carrying the b mb The observing planes will stay several miles distant from the point of impact of the bomb I Additional bombs will be ready for delivery at an accelerating rate increasing from about three in September to possibly seven in December with a sharp increase in production expected early in 1946 The sharp increase to seven in December is dependent upon the modification of the present implosion bomb which uses plutonium only to one using a combination of plutonium and uranium 235 This appears to be thoroughly sound and to offer no difficulty in production All bombs will be delivered by the 509th Composite Group on targets having a high priority at the time of delivery Instructions concerning such targets will be issued through the Commanding General U S Army Strategic Air Forces 7 Organization Major General L R Groves has overall direction of the atomic fission bomb project Brigadier General T F Farrell General Groves' deputy and Rear Admiral W R Purnell the Navy member of the Military Policy Committee will be at the base prior to the first mission to coordinate the project with Army and Navy Commanders in the theatre The Air Forces operations will be under the command of General Spaatz commanding U s Army Strategic Air Forces The 20th Air Force is under the command of Majo General Curtis Le May The 509th Composite Group is under the command of Colonel Paul Tibbets 8 On my recommendation the Joint Chiefs of Staff recently reserved the three cities from attack by any of our forces pending further instructions from them 9 It is recommended that you approve the above plan of operations and issue a tentative directive to General Spaatz for action with copies to General MacArthur and Admiral Nimitz for their information Final approval with modifications if desired can be given later A draft of the tentative directive and of a necessary action by the Joint Chiefs of Staff are attached Tabs B and C • TAB B TENTATIVE Draft of Directive by the Chief of Staff to General Spaatz with copies for information to General MacArthur and Admiral Nimitz i 1 The 509th Composite Group 20th Air Force will deliver its first special bomb as soon as weather will permit visual bombing after about 3 August 1945 on one of the targets Hiroshima Kokura and Niigata in the priority listed To carry military and civilian scientific personnel from the War Department to observe and record the effects of the explosion of the bomb additional aircraft will accompany the airplane carrying the b mb • The observing planes will stay several miles distant from the point of impact of the bomb 3 2 Additional bombs will be delivered on the above targets as soon as made ready by the project staff Further instructions will be issued concerning targets other than tbos listed above 3 Dissemination of any and all information concerning the use of the weapon against Japan is reserved to the Secretary of War and the President of the United States No communiques on the subject or releases of information will be issued by Commanders in the field without specific prior authority Any news stories will be sent to the War Department for special clearance TAB C SUBJECT Recommended Action by the Joint Chiefs of Staff TO General Admiral General General MacArthur Nimitz Arnold Spaatz The injunction against attack of Hiroshima Kokura and Niigata covered in Joint Chiefs of Staff action----- is removed and the targets are released to the Commanding General U S Army Strategic Air Forces for attack only by the 509th Composite Group 20th Air Forces