Brief of Downfall By: United States Army Forces, Pacific, [1945]

Brief of Downfall By: United States Army Forces, Pacific, [1945]

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21 Jtiae 1945 HSMOHAHBOM JOB THE GHIBff, S&P SQUTSC91 Brief of DOWH?AS.. Several Sail has already been briefed on this plan.,' It is recomtnended that this plan s^ld» released to afte/the Ksnto Plain has Deen secured. S. JO»SOI Colonel, GSC Chief, Strategy Section iifjca^cs! changed to by O.. -._... by

BRISF OF " DOWNFALL" 1. Scope. idowhfall is General MaeArthur 1 s strategic plan for operations in the Japanese Archipelago. It constitutes the basis for directives for operations to force the unconditional surrender of Japnn by seizure of vital objectives in the Japanese Archipelago. The plan outlines: at. Existing directives. b. Assumptions concerning enemy intentions.. * c. Operations. d. Logistics. It gives the "broad outlines of Operations OLTSPIC and COKQSSff but does not go into details (see Map A). 2. Phases. Jhe plan visualizes attainment of the assigned objectives by two successive operations. I a. - fo advance our land-based sir forces into Southern f ~. Kyushu is order to support the second, ia knock-out blow to the enemy's heart in the fokyo area. b. COSDITBT - A major joint assault supported by the massed air and naval power in the Pacific to destroy hostile forces and seize the Jokyo - Yokohama Area. c. Subsequent operations continued and extended until such organized resistance in the Japanese Archipelago ceases. 3. Snemy 3 Biv» in Northern Kyushu 3 Diva in -aircaft. '

3T7D7 DDSS7aa B 21 Divs in Honshu 14 Sirs employed in Ksnto Plain area. Hostile capability for sir action reduced to suicide attack* of uncertain proportions at an early phase of the operations. 4. Qwa - 12 Biv«- 2 21 vs (including 1 A/B reserve - 3 Divs, If required, divisions set up for, ; rdympio and replaced from strategic Forces - see Map A, - 14 Diva (including.9 Araiored '- 11 Divs (including 1 A/B reserve - 3 Divs 5. / -,.'' Command and Losi. sties. reserve in 0SA - 4 Divs per month b< - see Map A. - Philippines - 9 Divs Okinawa - 1 Uiv Marianas - 1 Biv S.;^ S^i«^^''3;''S^fi^^; '

i i XX <J\ YEL LOW SEA Total Enemy committed to V v \ r- ^- MANCHURIA t. I \ REPUBLICS ^_- r Enemy employed in CORONET k I iv*ar - i2 QFS 1 JUN - 50 6PS ASSAUL" XX 3, 3 XX X 9 XX < _ ) 2 CORONET r FOLLOW-UP X X 1 MAR 46 [><C 10 X X D><d 1 SAKHALIN I Cl NCAFPAG FOR OPERATIC JAPANESE ATO ( Pursuant to JCS1259 and W^8>938, OWN SEA OF 0 K H. 0 T S K

Enemy employed in CORONET APAN SEA MANCHURIA Total Enemy committed to I JUN-34 GPS I MAR - 30 GPS I JUN - 19 GPS

- MARIANAS IS 2.-*upan M f AFPAC RES. 24 GPS ( 23 GPS 4 CI7S P R MONTrt iff Oa. if SUPPORTING OPS (GORONET^uluIs XX MAV e USED FOR OR EXPANSION OR OTHER S'JeSlDWHK OPS. AL.LIED AIR FORCES 19 GPS (Rear Area Garrisons) Kapingamarangi Is New Ireland \-. NEW GUINEA A R A F O E R A SEA 1 MAR - 12 v3ps I JUN - 12 GPS SOUTH CHINA SEA PHILIPPINE L* ISLANDS 5 UL U SEA CELEBES

ELAGO >38, 26 :59/4, Vlay 1945) 3 April 1945 '-UP Komandoraki Is Shemya I. o COMMAND SET-UP JCS (JOINT ACTION) C1NCAFPAC (SUPPORT) LEGEND Seaplane Anchorage Ramp, hauling out facilities, refueling facilities, and major repairs-.. Seaplane Anchorage Limited repair and refueling facilities Emergency Seaplane Anchorage Limited or no facilities,,. Maximum Run Over 2 miles..._... Maximum Run 1 to 2 miles..._._._._._... Maximum Run Less than 1 mile -_-. -. Landing Field D efueling facilities and major repairs. Landing Field Limited repair and refueling facilities. Runway 4000 feet and over..,.-.._... Runway 2000 to 4000 feet... - Runway Less than 2000 feet.

si ET FOLLOW-UP X X CG 6thArmy FORCES 6th Army 9 Divs 3 Mar Divs I 1 3 Div A/B Div Divs CORONET AFPAC 8th Army 10th Army J Assau It Follow-up AFPAC Res. Kure DIVS 1 GG ASF COMMAND "0" GARRISONS AS ASSIGNED CG FEAF GGlUSA WEJJPAG CG I0th Army (JOINT ACTION) (SUPPORT) JCS COMMAND SET-UP Midway H A CG I st Army French Frigate Shoals ' Necker I Gardner Pinnacles A CjGASF COMMAND'^ Runway 2000 to 4000 feet...... Runway Less than 2000 feet..._.. Seaplane Anchorage Ramp, hauling out facilities, refueling facilities, and major repairs.-... Seaplane Anchorage Limited repair and refueling facilities Emergency Seaplane Anchorage Limited or no facilities.._ Maximum Run Over 2 miles..._...._.._. Maximum Run 1 to 2 miles _-_------_-_.. Maximum Run Less than 1 mile Landing Field ''efueling facilities and major repairs. Landing Field Limited repair and refueling facilities. Runway 4000 feet and over. -_-._._. LEGEND

^ 10' 3 MarDivs f AssaulT 2 Armd DivsJ 1st Army -Dtvl f hollow-up I A/B Div 3 Divs - AFPAC Res. 25 DIVS ^ Oahu 1 MAR - I JUN -! I GP CONCEPT Initial assaults seize and develop KAGOSHIMA WAN and ARIAKE WAN Occupy area as far north as gerieral line TSUNO - SENDAI. CORONET * JTnhnatnn T as ports of entry. Initially establish local air support and drive into KANTO PLAIN from outlying beaches while defences of approaches to TOKYO-WAN and Northern SAGAMI BAY are reduced by intensive naval and air action. Thjen occupation of TOKYO-YOKOHAMA cirea and rest of KANTO PLAIN. ISLANDS 1. In event commitment for DOWNFALL exceeds forces projected, build-up of 4 divs per month from USA begins June 1946. 2. Air Redeployments :- I Nov 45 - I Jun 46-47 Gps 3. Ultimate VHB Garrisons :- Marianas - 20 Gps Ryuky^js - I 2 Gps "Palmyra I Wwhington I ' Fanning I ^X Christmas I Tarawa ' v GILBERT Howland I Baker I ISLANDS Jarvis I P H O E N I X ISLANDS E L L I C E ISLANDS Wake 1 Taongi Atoll ' MARSHALL - ' Kwajalein Jaluit _ Nauru ' Ocean 1 * 5.<cj Ponape s " ' -, -.j v aeul. " ' *- -k- \\ Malaita