Campaign in the Marianas

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UNITED ST TES RMY IN WORLD W R II

The War in the Pacific

C MP IGNIN THE M RI N S

byPhilip A. Crowl


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ForewordIn the capture of the southern Marianas, including the recapture of Guam,

during the summer of 1944, Army ground and air forces played an important,though subordinate, role to that of the Navy and its Marine Corps. Marinepersonnel constituted the bulk of the combat troops employed. The objective ofthis campaign was "to secure control of sea communications through theCentral Pacific by isolating and neutralizing the Carolines and by the establish-ment of sea and air bases for operations against Japanese sea routes andlong-range air attacks against the Japanese home land." Its success would pro-vide steppingstones from which th e Americans could threaten further attackwestward toward the Philippines, Formosa, and Japan itself, and would gainbases from which the Army Air Forces' new very long range bombers, theB-29's, could strike at Japan's heartland. Recognizing and accepting the chal-lenge, the Japanese Navy suffered heavy and irreplaceable losses in theaccompanying Battleof the Philippine Sea; and the islands after capture becamethe base for all the massive air attacks on Japan, beginning in November 1944.

In the operations described in the present volume, landings against strongopposition demonstrated the soundness of the amphibious doctrine and tech-niques evolved out of hard experience in preceding Pacific operations. Bitterinland fighting followed the landings, with Army and Marine Corps divisionsengaged side by side. The author's account and corresponding Marine Corpshistories of these operations provide ample opportunity to study the differencesin the fighting techniques of the twoservices. Dr. Crowl also deals frankly withone of the best-known controversies of World War II, that of Smith versusSmith, but concludes that it was the exception to generally excellent interserviceco-operation.Withteam effort among th emilitary servicestheorder of theday, this recordof the Army's experience in working with the Navy and the Marine Corpsshould beparticularly valuable both now and in the future.

WARREN H. HOOVER


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The AuthorPhilipA. Crowl, who has an M.A. from the State University of Iowa and a

Ph.D. from the JohnsHopkins University, taught History at the Johns HopkinsUniversity and at Princeton. Commissioned in the Navy in World War II, hebecamea lieutenant (senior grade) and commanding officer of an LCI gunboatthat was in action at Leyte Gulf, Lingayen Gulf, and Okinawa. From 1949through 1956, Dr. Crowl was a historian with the Office, Chief of MilitaryHistory. He was awarded the James V. Forrestal Fellowship for 1953-54 tostudy command relationships in amphibious warfare in World War II. Since1957 he has been in Department of State Intelligence. Dr. Crowl is author ofMaryland During and After the Revolution (1943) and coauthor of The U.S.Marines an d Amphibious War ( 1 9 5 1 ) an d Seizure of the Gilberts and Marshalls(1955) .


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PrefaceThis volume is a companion piece to Seizure of the Gilberts and Marshallsby Philip A.Crowl and Edmund G. Love, alsopublished in the Pacific subseries

of the UNITED STATES A R M Y IN WORLD WAR II. Together, the twovolumes cover the beginning and climax (although not the conclusion) of theCentral Pacific phase of the war against Japan, with special emphasis, ofcourse, on the U.S. Army's contribution to the victories won in that area.1Specifically, Campaign in the Marianas treats of the capture of Saipan, Tinian,and Guam in the southern Marianas; the strategic and tactical plans leadingthereto;supportingoperations by naval and air units; and the final developmentand exploitation of these islands as bases for furtherance of American jointoperationsagainst theJapanesehomeland.

The word joint cannot be overemphasized in connection with any considera-t ion of U.S. operations in the Central Pacific. It was predominantly a U.S.Navy theater under the command of Admiral Chester W. Nimitz. The mainburden of the amphibious and ground fighting in the Marianas, as in theGilberts and Marshalls, fell on the shoulders of the U.S. Marine Corps, whosetroopsfar outnumbered thoseof theU.S.Army. The author recognizes this andrecognizes also that, by concentratingon the activitiesof the Army, this volumein a sense presents a distorted picture. The distortion is deliberate. The bookrepresents, by definition, one segment of the history of the U.S. Army in WorldWar II. Excellent official and semiofficial histories of U.S. Navy and U.S.Marine Corps operations in the Marianas have already been published. Thepresent narrative of Army activities should add in some measure to what hasalready been written about the campaign. The reader may also gain additionalinsightintothenatureof jointoperationsand interserviceco-ordination.

Because thenumberofArmytroopsparticipating in the Marianas Campaignwas comparatively small, it has been possible to devote more attention here tosmall unit actions than in the volumes of the series that deal with the move-ments of great armies and corps over large continental land masses. In muchof this narrative th e spotlight centers on the infantry company. Ideally, as


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accompanied the troops and who were to supplement and correct the officialrecords by conducting on-the-spot interviews, mostly neglected the artillery infavorof themore mobileinfantry.

No really adequate acknowledgment can be made to the many kind andindustrious people who helped to bring this book to completion. On substantivematters of strategy and tactics, Dr. Louis Morton, Chief of the Pacific Section,Office of the Chief of Military History, during the preparation of this volume,was a tireless and able critic. On questions of literary style, Dr. Kent RobertsGreenfield, formerly Chief Historian, Department of the Army, was the same.The final editing of the manuscript was performed by Miss Mary Ann Bacon,whose eye for detail is remarkable. None of them is responsible for any errorsof fact and interpretation or gaucheries of style I may have persisted in despitetheirstern warnings.To all I amverygrateful.

I owe a special debt ofgratitude to Mr, Wsevolod Aglaimoff whose serviceswent fa r above an d beyond the call of his duties as Deputy Chief Historian forCartography. His maps speak for themselves. What is not so apparent is hismeticulous scrutiny of the written narrative presented here and his expert ad-vice on all matters tacticaladvice based on almost a half-century's intensivestudy ofmilitarytactics.Maj. Gen. A. C. Smith, formerly Chief of Military History, Col. George G.O'Connor, formerly Chief of War Histories Division, and the military membersof their staffs were liberal in their technical assistance and made it possible fo rme to have access to the classified source material upon which this volume isbased.Mr.ThomasWilds is responsible forunearthing,insomecasestranslating,and in most cases interpreting the widely scattered and often obscure Japanesesource material upon which is based the account of enemy plans, defensivepreparations, and combat activity. MissMargaretPlumb began and Mr. StanleyL. Falk completed a highly useful study of the Guam phase of the campaign.M r. Falk's excellent draft narrative of the operations of the 77th InfantryDivision on Guam forms the basis for the account of that division's actionspresented here. Loretto Carroll Stevens was copy editor for the volume andNorma Heacock Sherris was responsible for the selection of photographs. TheIndex was compiled by Nicholas J. Anthony. Mr. Israel Wice, Chief Archivist,General Reference Branch, and his staff an d Miss Lois Aldrich of the WorldWar II Records Division, NARS, were unfailingly patient and courteous. Thedebt to officers of the Army , Navy, and Marine Corps who read and criticized


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ContentsPART ONE

IntroductionChapter Page

I . BACKGROUND O F STRATEGY . . . . . . . . . . .1Prewar Originsof the Central Pacific Concept . . . . . . 2War in the Pacific: First Year . . . . . . . . . . . 4Revival of the Central Pacific Concept . . . . . . . . 6General MacArthur's Strategy . . . . . . . . . . . 9Enter the Army Air Forces . . . . . . . . . . . . 11Cairo Conference . . . . . . . . . . . . . . . . 1 2Scheduling Operations . . . . . . . . . . . . . . 1 3Acceleration of Operations . . . . . . . . . . . . 14Washington Planning Conferences: FebruaryMarch 1944 . . 15

I I . T H E MARIANAS . . . . . . . . . . . . . . . . . 21I n History . . . . . . . . . . . . . . . . . .2 1The Japanese Invasion o f Guam . . . . . . . . . . 22Description of the Islands . . . . . . . . . . . . . 24

PART TWO

Saipan


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Chapter PageIV. THE ENEMY . . . . . . . . . . . . . . . . . . 53Prewar Japanese Activities in theMarianas . . . . . . . 53

From Pearl Harbor to Invasion . . . . . . . . . . . 55Japanese Doctrine for Island Defense . . . . . . . . . 62Enemy Troop Strength and Dispositions onSaipan . . . . 64Japanese Expectations . . . . . . . . . . . . . . 6 9

V . INVASION . . . . . . . . . . . . . . . . . . . 7 1Softening the Target: Pre-D-Day Bombardment . . . . . 71D-Day Bombardment andShip-to-Shore Movement . . . . 78Breakdown of theLanding Plan . . . . . . . . . . . 85Expanding t h e Beachhead . . . . . . . . . . . . . 8 7Summary of the Situation at Nightfall . . . . . . . . 93

V I . CAPTURE O F ASLITO AIRFIELD . . . . . . . . . . 9 5Counterattack: Night of 1516 June . . . . . . . . . 95Consolidating the Beachhead: 16 June . . . . . . . . 96Night of 1617 June . . . . . . . . . . . . . . . 98Change o f Plans . . . . . . . . . . . . . . . . 9 8First Landings of the 27th Infantry Division . . . . . . 99D Plus 3: 17 June . . . . . . . . . . . . . . . 101D Plus 3: 18June . . . . . . . . . . . . . . .1 11T h e Japanese Situation . . . . . . . . . . . . . . 1 1 6

VII. SUPPORTING ARMS AND OPERATIONS . . . . . . . 119Battle o f t h e Philippine S e a . . . . . . . . . . . . 1 1 9Logistics . . . . . . . . . . . . . . . . . . . 1 2 3Postlanding Naval Gunfire Support . . . . . . . . . 129Close A i r Support . . . . . . . . . . . . . . . 1 31Artillery . . . . . . . . . . . . . . . . . . . 1 3 3


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Chapter PageIX. THE FIGHT FOR CE N T RA L SAIPAN I . . . . . . . 163Preparations for the Drive to theNorth . . . . . . . . 163

2 2June T h e Jump-off . . . . . . . . . . . . . . 1 6 723June: Into Death Valley . . . . . . . . . . . . 1 7 0The First Night in Death Valley . . . . . . . . . . 17923June: Marineson theFlanks . . . . . . . . . . . 18024 June: Action of the 27thDivision . . . . . . . . . 1812 4 June: Action on the Flanks . . . . . . . . . . . 187

X . SMITH VERSUS SMITH . . . . . . . . . . . . . . 1 91Relief o f Major General Ralph C . Smith . . . . . . . 1 9 1Interservice Controversy . . . . . . . . . . . . . 1 9 2Conclusions . . . . . . . . . . . . . . . . . . 1 9 7

XI. THE FIGHT FOR CENTRAL SAIPAN II . . . . . . . 2032 5 June . . . . . . . . . . . . . . . . . . . 2 0 3T h e Plight o f t h e Japanese . . . . . . . . . . . . 2 112 6 June . . . . . . . . . . . . . . . . . . . 2 1 32 7 June . . . . . . . . . . . . . . . . . . . 2 1 6Japanese Reactions . . . . . . . . . . . . . . . 2 2 12 8 June . . . . . . . . . . . . . . . . . . . 2 2 12 9 June . . . . . . . . . . . . . . . . . . . 2 2 73 0 June . . . . . . . . . . . . . . . . . . . 2 3 0Central Saipan: Sum-up. . . . . . . . . . . . . . 2 3 2

XII. THE CAPTURE OF NORTHERN SAIPAN . . . . . . . 235Drive t o Tanapag . . . . . . . . . . . . . . . . 2 3 5Change o f Direction . . . . . . . . . . . . . . . 2 4 45 July . . . . . . . . . . . . . . . . . . . . 2 4 46 July . . . . . . . . . . . . . . . . . . . . 2 4 77 July . . . . . . . . . . . . . . . . . . . . 2 5 6Final Victory . . . . . . . . . . . . . . . . . 2 6 2


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Chapter PageXIV. INVASION A N D CA P T U RE . . . . . . . . . . . . . 2 85Preliminary Bombardment . . . . . . . . . . . . . 2 8 5

T h e Landings . . . . . . . . . . . . . . . . . 2 8 8Japanese Counterattack: 2425 July . . . . . . . . . 2 9 3Capture o f Northern Tinian . . . . . . . . . . . . 2 9 4Drive to the South . . . . . . . . . . . . . . . 2 9 6Tinian Secured . . . . . . . . . . . . . . . . . 3 0 1

PART FOUR

GuamX V . PLANS A N DPREPARATIONS . . . . . . . . . . . . 3 07

T h e Island . . . . . . . . . . . . . . . . . . 3 07Plans f o r t h e Invasion . . . . . . . . . . . . . . 3 09Change o f Plans . . . . . . . . . . . . . . . . 3 1 477th Infantry Division Training and Preparation . . . . . 315Loading a n dEmbarkation . . . . . . . . . . . . . 3 1 8Preliminary Bombardment . . . . . . . . . . . . . 3 2 0Intelligence of the Enemy . . . . . . . . . . . . . 3 2 6

XVI. T H E ENEMY . . . . . . . . . . . . . . . . . . . 3 2 9Troops a n d Troop Dispositions . . . . . . . . . . . 3 2 9Supporting Weapons . . . . . . . . . . . . . . . 3 3 3Fortifications . . . . . . . . . . . . . . . . . 3 3 4Japanese Situation on the Eve of Battle . . . . . . . . 335

XVII. T H E FIGHT FOR THEBEACHHEAD . . . . . . . . . 3 39W-Day Preliminary Bombardment . . . . . . . . . . 3 3 9


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Chapter Page

XVIII. T H E ASSAULT COMPLETED: 2530JULY . . . . . . . 3 61Preparations for the Assault onOrote:25July . . . . . . 362The Fight in the North: 25 July . . . . . . . . . . 363Japanese Counterattack: 2526 July . . . . . . . . . 3 6 4T h e Capture o f Orote . . . . . . . . . . . . . . 3 6 7The Capture of Fonte and the Force Beachhead Line ... 371Reconnaissance o fSouthern Guam . . . . . . . . . . 3 7 4

XIX. PURSUIT T O T H E NORTH . . . . . . . . . . . . 3 77T h e Japanese Withdrawal . . . . . . . . . . . . . 3 7 7Drive to the O2Line:31 July1 August . . . . . . . . 378Supply Problems . . . . . . . . . . . . . . . . 3 8 3To Barrigada and the O3 Line: 24 August . . . . . . 38677th Division: 3 August . . . . . . . . . . . . . 3 9 877th Division: 4 August . . . . . . . . . . . . . 4 02T h e Marines: 2 4 August . . . . . . . . . . . . . 4 07

X X . GUAM SECURED . . . . . . . . . . . . . . . . 4 0 977th Division:56August . . . . . . . . . . . . . 4 0 93 dMarine Division:5 6August . . . . . . . . . . . 41 7Capture ofMount Santa Rosa: 78August . . . . . . . 417TheMarines: 7 8August . . . . . . . . . . . . . 4 3 4T he End on Guam . . . . . . . . . . . . . . . 4 3 6

PART FIVEConclusion

XXI. FRUITS OF VICTORY . . . . . . . . . . . . . . 4 41AppendixA. TacticalUnitsofNorthern Troopsand LandingForceon Saipan . . 449

B. Pacific Ocean Area UnitofFireforGround Weapons . . . . . . 452C. Japanese Order of Battle on Saipan . . . . . . . . . . . 453D. TroopListof the 77th Infantry Divisionfor the GuamOperation . . 455


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TablesNo. Page1 . Estimated Strength of the Japanese Garrison on Tinian . . . . . . 2 792 . Artillery o n Guam . . . . . . . . . . . . . . . . . . . 3 3 3

Charts1. Task Organization for Major Commands for Attack on Saipan

a n d Tinian . . . . . . . . . . . . . . . . . . . . 3 42. Task Organization for Major Commands for Attack on Guam . . . . 31 0

Maps1. Pacific Ocean Areas, 15June 1944 . . . . . . . . . . . . . 52 . Southern Marianas . . . . . . . . . . . . . . . . . . . 2 53 . Japanese Defense Sectors o n Saipan . . . . . . . . . . . . . 6 64. D-Day on Saipan, 15June 1944 . . . . . . . . . . . . . . 825. Advance 1618 June . . . . . . . . . . . . . . . . . . 1 076. Advance 1922 June . . . . . . . . . . . . . . . . . . 1 6 27 . Into Death Valley, 2324 June 1944. . . . . . . . . . . . 1 7 18 . 27th Division, 2 5 June 1944 . . . . . . . . . . . . . . . 2 0 29 . 27th Division, 2627 June 1944 . . . . . . . . . . . . . . 2 1 91 0 . 27th Division, 2830 June 1944 . . . . . . . . . . . . . . 2 2 3

1 1 . Drive toTanapag, 1 4July 1944. . . . . . . . . . . . . . 2 3612 . 105th Infantry, Morning, 6 July 1944 . . . . . . . . . . . . 2 4 91 3 . 105th Infantry, Afternoon, 6July 1944. . . . . . . . . . . . 25514. Last Days of Battle on Saipan, 79 July 1944 . . . . . . . . . 26215. JapaneseDefense Sectors on Tinian . . . . . . . . . . . . . 28116. Capture of Tinian, 24 July1 August 1944 . . . . . . . . . . 2901 7 . Disposition of Japanese Troops on Guam, July 1944 . . . . . . . 330


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MapsIVIIAre in Accompanying MapEnvelopeI. Saipan Island

II. 27th Division, 1622June 1944III. Advance56JulyIV. Tinian IslandV. Island of GuamV I. NorthernBeachhead, 2125July 1944

VII. Southern Beachhead, 2125July 1944

IllustrationsPageTop Naval Commanders in the MarianasCampaign . . . . . . . . 36

Vice Adm.Richmond Kelly Turner . . . . . . . . . . . . . . 3 7L t . Gen. Holland M . Smith . . . . . . . . . . . . . . . . . 38Maj. Gen.Ralph C . Smith . . . . . . . . . . . . . . . . . 3 9Destruction a t Charan Kanoa . . . . . . . . . . . . . . . . 7 5D u m m y Searchlight Platform o n East Coast o f Saipan . . . . . . . 7 7Japanese Type 9 6 25-mm. Machine Cannon . . . . . . . . . . . 7 8Amphib ian Tractors in Line Abreast Formation . . . . . . . . . 81Congestiono n d M arine Division Beach . . . . . . . . . . . . 8 4Early Wave on the Beach . . . . . . . . . . . . . . . . . 88Marines Digging Foxholes . . . . . . . . . . . . . . . . . 9 0D-Day Command Post . . . . . . . . . . . . . . . . . . 9 1Narrow-Gauge Railroad Near Charan Kanoa . . . . . . . . . . 1 0 2Soldiers Watch Destruction o f a Pillbox . . . . . . . . . . . . 1 0 3Reinforcements Moving Inland . . . . . . . . . . . . . . . 1 0 4105th Infantrymen Wading in From the Reef . . . . . . . . . . 10 8Aslito Field Becomes Conroy Field . . . . . . . . . . . . . . 1 1 3Examining a n Enemy G u n . . . . . . . . . . . . . . . . . 1 15Shore Parties Unloading Supplies o n Blue Beach 1 . . . . . . . . 1 2 5Caterpil lar Tractor Pulling Ammuni t ion Pallets From a n L C M . . . . 1 2 6Pontoon Causeway and Barge in Charan Kanoa Harbor . . . . . . 127
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PageJapanese Type 93 13.2-mm. Machine Gun . . . . . . . . . . . 166Japanese Field o f Fire . . . . . . . . . . . . . . . . . . . 1 6 7M t . Tapotchau Dominating Death Valley . . . . . . . . . . . 1 7 4Tree Line in Death Valley . . . . . . . . . . . . . . . . . 1 7 5Driven t o Concealment . . . . . . . . . . . . . . . . . . 1 7 6Marines Emerging From Purple Heart Ridge Complex . . . . . . . 180Tank-Infantry Co-operation . . . . . . . . . . . . . . . . 1 8 5I n Hell's Pocket Area . . . . . . . . . . . . . . . . . . 1 8 9Inland o f Garapan Harbor . . . . . . . . . . . . . . . . . 1 9 0Maj. Gen. Sanderford Jarman . . . . . . . . . . . . . . . . 1 9 3L t . Gen.Holland M . Smith . . . . . . . . . . . . . . . . 194Lt . Gen. Robert C .Richardson,J r . . . . . . . . . . . . . . . 195Maj. Gen. Ralph C . Smith . . . . . . . . . . . . . . . . . 1 9 7Lower End of Death Valley . . . . . . . . . . . . . . . . 208Bazooka Team Preparing t o Fire . . . . . . . . . . . . . . 214Maj. Gen.George W.Griner . . . . . . . . . . . . . . . . 225Truck-Mounted Rocket Launchers Firing . . . . . . . . . . . . 2 2 9MarinesDash Through BlazingGarapan . . . . . . . . . . . . 239Infantrymen Observe Hill 7 6 7 . . . . . . . . . . . . . . . 2 4 0Troops Searching Out the Enemy . . . . . . . . . . . . . . 2 43Harakiri Gulch . . . . . . . . . . . . . . . . . . . . 2 4 6Waiting T o Move U p . . . . . . . . . . . . . . . . . . 2 52Marines Examining Destroyed Enemy Tank . . . . . . . . . . . 2 6 0FlameThrower Blasting Paradise Valley Cave . . . . . . . . . . 263Coastal Area, Northwest Tinian . . . . . . . . . . . . . . . 2 7 0Marianas Leaders Confer a t Tinian . . . . . . . . . . . . . . 2 7 3L V T With Ramp . . . . . . . . . . . . . . . . . . . . 2 7 6155-mm. GunFiring at Tinian From Saipan . . . . . . . . . . . 287Invasion Craft . . . . . . . . . . . . . . . . . . . . . 2 9 24th Marines Wading Toward White Beach 1 . . . . . . . . . . 293Ushi Point Airfield . . . . . . . . . . . . . . . . . . . 2 9 6OpenTerrain o fCentralTinian . . . . . . . . . . . . . . . 2 9 7155-mm. Howitzer Emplacement o n Tinian . . . . . . . . . . . 2 9 8Cliff Line at Tip of Orote Peninsula . . . . . . . . . . . . . 308Orote Peninsula . . . . . . . . . . . . . . . . . . . . 3 0 9


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PageSmouldering Japanese Tanks . . . . . . . . . . . . . . . . 3 5 3Maj. Gen.Andrew D. Bruce . . . . . . . . . . . . . . . . 354Pontoon Barge With Crane . . . . . . . . . . . . . . . . 3 5 8Troops i n Bivouac . . . . . . . . . . . . . . . . . . . . 3 6 2Japanese Airfield, thePrimeObjective onOrote Peninsula . . . . . . 366Marine Corps Officers . . . . . . . . . . . . . . . . . . 3 7 0Anti tank Crew . . . . . . . . . . . . . . . . . . . . . 3 7 3M e n o f Company B , 305th R C T . . . . . . . . . . . . . . 3 81Forward Observers of the 77th Division . . . . . . . . . . . . 383Artillery Column Moving Inland . . . . . . . . . . . . . . 3 8 5M t . Santa Rosa . . . . . . . . . . . . . . . . . . . . 4 18Burning U.S.Medium Tanks . . . . . . . . . . . . . . . . 4 2 6Lt . Gen.Alexander A . Vandegrift . . . . . . . . . . . . . . 435LST's, LCI's, Small Boats . . . . . . . . . . . . . . . . . 44.2Harmon Field, Guam . . . . . . . . . . . . . . . . . . . 4 4 4

Photographs are from Department of Defense files with the following excep-tions: photographs on pages 37 and 38 from the personal files of Col.Robert C.Richardson, I I I ;the photograph on page 418 from the Bishop Museum, Oahu,Hawaii;and thatonpage444,by J. R. Eyerman-Life, (c) 1950TimeInc.


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TheU.S. ArmyCenterofMilitaryHistoryThe Centerof Military Historypreparesand publishes historiesas re-

quired by the U.S. Army. ItcoordinatesArmyhistoricalmatters, inc lud inghistorical properties, and supervises the Army museum system. It alsomaintainsliaison withpublic and privateagenciesand individuals to s t imu-lateinterest and studyin the field of militaryhistory.The Centerislocatedat 1099 1.4thStreet,N.W., Washington, B.C.20005-3402.


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PARTONEINTRODUCTION


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CHAPTER I

Background of StrategyOn 15 June 1944American forces in -

vaded the island of Saipan thus piercingthe first hole in the inner line of islandfortifications that the Japanese had labori-ously constructed in order to defend theirhomeland, their empire, and their recentconquests in the western Pacific and inAsia. Saipan is 1,270nautical miles fromTokyo, 1,430from Manila, 1,640fromShanghai, and 3,350 from Honolulu. Lo-cated in the southern portion of the Mari-anaschain, it was themost heavily fortifiedof that group of islands and was consid-ered by the Japanese to be a keystone inthe defensive system for the homeland.After twenty-four days of strenuousbat-tle and much bloodletting on the part ofboth victor and vanquished, Saipan wasconquered. On 1 August th e little islandof Tinian, just a few miles to the south,fell to U.S.forces, and in the same monthGuam, the southernmost of the Marianaschain, was recaptured from th e Japanese,who had wrested it from the Americansduring the first days of the war.Speaking of the fall of Saipan, Fleet Ad-mira l Osami Nagano, SupremeNaval A d-

face an unprecedentedly great nationalcrisis."The following month Tojoresignedin disgrace along with his entire war cabi-net. His resignation marked a major turn-ing point in the war.Up to that time themilitary clique, led and symbolized byTojo, had been in secure control of themachinery ofgovernment and had dictatedImperial policy without any effective re -straints. Thereafter, an opposition partywith strong inclinations toward terminat-ing the war made gradual but steady in-roads into the councils of state, until atlast it was able to persuade the Emperorto surrender. The loss of Saipan and theoverthrow ofTojogavethis peaceparty itsfirst opportunity.2The spark that set off this interestingtrain of events was a directive issued bythe U.S.JointChiefso f Staff on 12March1944.3 This bodyconsisting of AdmiralWilliam D. Leahy, President Franklin D.Roosevelt's chief of staff; Admiral ErnestJ. King, Chief of Naval Operations andCommander in Chief, U.S.Fleet; GeneralGeorge C. Marshall, Chief of Staff, U.S.A r m y ; and General Henry H. Arnold,


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2 C A M P A I G N IN THE MARIANASCommanding General, U.S.Army AirForceswas responsible, under the Presi-dent and in conjunction with its Britishcounterpart, for the strategic direction ofWorld War II. On 12 March it orderedAdmira l Chester W. Nimitz, Commanderin Chief, U.S.Pacific Fleet and PacificOcean Areas, to occupy the southernMarianasbeginning 15June next. The ob-jective as stated was to secure control ofsea communications through the CentralPacific by isolating and neutralizing theCarolines and by the establishment of seaand air bases for operations against Japa-nese sea routes and long range air attacksagainsttheJapanesehomeland."

The 12Marchdirective was the productof a slow if not always steady growth,emerging only after a long and sometimesbitter conflict of strategic ideas, militaryinterests, and personalities. A leading issueof this conflict was what can best be calledthe "Central Pacific concept" ofAmericanstrategy in a war against Japan.

Prewar Origins of theCentral Pacific Concept

Shortly after the termination of WorldWar I, when Japan's pretensions in thewestern Pacific and the Far East were be-coming steadily more apparent, Americanstrategic planners set to work to examine

Army-Navy effort, these were issued byth e Joint Army and Navy Board, the pre-decessor to the Joint Chiefs of Staff.Although th e several plansvaried in de-tail, certain assumptions remained fairlyconstant. The basic concept of the waragainst Japan, as expressed by the JointBoard in 1929, was that it would be "pri-marily naval in character throughout, un-less large Army forces are employed inmajor land operations in the Western Pa-cific, directed toward th e isolation and ex-haustion of Japan, through control of hervital se a communications and through ag-gressive operations against her armedforces and her economic l i f e . 5 To con-duct such a war,the U.S. Fleet must firstmove west from Hawaii and establish anadvanced naval base in the Philippines,preferably at Mani la Bay if it could beheld. Such an advance would be either adirect movement or a step-by-step processinvolving seizure and occupation of keyJapanese Mandated Islands in the Mar-shalls and Carolines, depending upon thenature and extent of the enemy resistance.From a naval base in the Philippines, itwas presumed that Japanese trade routesthrough the South China Sea could be cutand Japan's economic life throttled. Amer-ican forces might also move north toestab-lish still more bases in the Ryukyus andother islands neighboring Japan, from


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BACKGROUND OF STRATEGY 3The plans assumed it would be essential

to establish subsidiary U.S. bases in theJapanese Mandates, especially in the Mar-shalls, for the purpose of protecting theline of communications between the Phil-ippines and the continental United States.It was generally agreed that bases in theMarshalls, and probably in the Carolines,would have to be occupied by U.S. forceseither in offensive operations in advance ofa fleet approach to the Philippines or as adefensive measure to protect the line ofcommunications of American forces oper-ating in the western Pacific. The Marianasfigured only incidentally in the scheme,since they lay north of the main route ofadvance from Hawaii to the Philippines.Thus first emerged the Central Pacificconcept ofstrategy.

The ORANGE plans were based on theassumption that the United States alonewould be engaged in a war with Japan.With the outbreak of war in Europe in1939, and with the gradual strengtheningof bonds between the United States andthe anti-Axis nations, especially Great Brit-ain, this assumption no longer held. It be-came necessary to agree to some combinedstrategic measures in anticipation of theday when the United States might active-lyenter the waragainstthe Axis.As a consequence, British and Americanmilitary staff representatives met in Wash-

should the United States be compelled toresort to war, both nations would con-sider theAtlantic and European area to be the decisive theater," since Germany wasthepredominant memberof the Axis Pow-ers. Thus was enunciated the doctrine of"beat Germany first that prevailed untilthe surrender ofGermany on 8 May 1945.Until the Germans were defeated, Alliedstrategy in the Far East would be primar-ily defensive. American and British forceswould defend Hong Kong, the Philip-pines,and theNetherlands Indiesand holdMalaya, Singapore, and Java against Jap-anese attack. Within this defensivepattern,the U.S. Navy was assigned the specificoffensive mission of capturing positions inthe Marshalls and preparing to establishcontrol over the entire Caroline and Mar-shall Islands area.8 Thus was restated themain principle of the ORANGE plans: holdthe Philippines, if possible, and gain con-trol over the islands and waters of theCentralPacific west ofHawaii.

In April 1941 the U.S. Joint Board setabout bringing its own plansup to date inthe light of these American-British Con-versations. The new strategicplan,entitledRAINBOW 5, merely restated the decisionsof ABC-1 and assigned more specific tasksto the U.S. forces. Germany was to bebeaten first; the Philippines were to be


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4 CAMPAIGN IN THE MARIANASagain, the role of the Central Pacific inthe forthcoming war against Japan wasaffirmed.

War in the Pacific: First YearThe rapid succession of Japanese vic-

tories after Japan's attack on Pearl Harbormade it impossible for the United Statesand her allies to put into immediate exe-cution any of the prewar plans. Guam fellto the invaders, followed by Hong Kong,Singapore, Manila, and the Philippine Is-lands. In short order the United Statesand Great Britain were stripped of all theusable advanced bases they once possessed,The Netherlands Indies, Malaya, andBurma were overrun and the BismarckArchipelago-New Guinea-Solomons areawasinvaded. By May of 1942the Japanesewere well ensconced in a far-flung systemof mutually supporting bases including th eKurils, the Marianas, the Marshalls, theCarolines, the Palaus, and Rabaul (inNew Britain), with outposts in the Gil-berts, the Solomons, and New Guinea.Flushed with victory, the Japanese highcommand decided to ride itsgood fortuneto the limit and push on to Port Moresby,New Guineathe very threshold of Aus-tralia; to NewCaledonia, Fiji, and Samoa,astride the sea lanes between Australia

June 1942.1 0 The time had come for Al-lied counteraction.The United States, which had assumedmajor responsibility for the war in the Pa-cific, had laid th e groundwork for futureoffensive operationsagainst the enemy. On30 March 1942the Joint Chiefs of Staff,with the approval of President Roosevelt,

organized the Pacific theater into twocommandsthe Southwest Pacific Area(SWPA) and the Pacific Ocean Areas(POA). The former fell to the commandof General Douglas MacArthur, withheadquarters in Australia, and includedAustralia, New Guinea, the Bismarck Ar-chipelago, the Solomons, the NetherlandsIndies (except Sumatra), the Philippines,and adjacent waters.11 The Pacific OceanAreas was to be commanded by AdmiralNimitz, whose headquarters was at PearlHarbor and who was concurrently Com-mander in Chief, U.S. Pacific Fleet. Thistheater included virtually the entire re-mainder of the Pacific Ocean. Within itsboundarieslay the Hawaiian Islands,Mid-way, Wake, the Gilberts, the Marshalls,th e Carolines, the Palaus, the Marianas,the Bonins, the Ryukyus, Formosa (Tai-w a n ) , and the Japanese home islands.12Because of the immensity of the theater, itwas subdivided into three areas, North,Central, and South Pacific. Nimitz di-rectly commanded th e first two, but as-


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BACKGROUND OF STRATEGY 5

MAP 1

signed the third to a subordinate com-mander who from October 1942 to June

the United States and Australia. On 2July 1942theJoint Chiefs of Staff ordered


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6 C A MPA IG N IN THE MARIANASSan Cristobal out of MacArthur's juris-diction. (Map 1 ) There followed thelengthy and exhausting Guadalcanal andPapua Campaigns. By January of 1943the line of communications was safe,even though Rabaul remained in enemyhands.14

The Japanese were at last on the de-fensive; the losses at Pearl Harbor weremore than replaced by the naval repairand construction program. Allied militaryplanners could now direct their attentionto devising ways and means of taking upthe offensive, and it is not surprising thattheir thoughts turned once again to theprewar plans for the Pacific.

Revival of the CentralPacific ConceptThe Casablanca Conference

In January 1943President Rooseveltand the U.S. Joint Chiefs of Staff metwith Prime Minister Winston S. Churchilland the British Chiefs of Staff at Casa-blanca, FrenchMorocco.There,theAmer-ican and British Chiefs, known collectively

as the Combined Chiefs of Staff, mappedout as best they could the main lines ofglobal strategy for the coming year.15 Inthe midst of prolonged and sometimesacrimonious discussion concerning forth-coming operations in Europe and theMediterranean, proposed offensives in Bur-ma, and aid to China, Admiral Kingstepped forth to assume the role that hewas to fill for the next tw o yearsthat ofthe leading advocate of a greater effort inthe Pacific and more specifically of a Cen-tral Pacific thrust against the Japanese.King addressed himself primarily to theproblem of where to go after Rabaul wascapturedan operation that was optimis-tically assumed to be already well ad-vanced with the campaigns in Guadal-canal and Papua drawing to a successfulclose. He adhered to the concept of theORANGE plans and urged that th e firstmain Allied objective in the Pacific be thePhilippines, since they lay athwart theline of communications between Japanand the oil-rich East Indiesandsince theiroccupation by Allied forces would permitthat line to be cut.The best route to thisobjective, he claimed, lay through theCentral Pacific. Such a drive would in-volve "establishing a base in the north-western Marshalls and then proceeding toTruk and theMarianas." "TheMarianas"he added, "arethe key of the situation be-

14 See John Miller, jr. ,Guadalcanal: The FirstOffensive (Washington, 1949) , and Samuel Mil-ner, Victory in Papua (Washington, 1957) , bothin UNITED STATES A R M Y IN WORLDWAR II series; Samuel Eliot Morison, History ofUnited States Naval Operations in World War


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B A C K G R O U N D OF STRATEGY 7cause of their location on the Japaneselineofcommunication."16A n impor tant addi t ion was thus intro-duced into th e O R A N G E concept of thewar in the Pacific. The Marianas, whichhad received little at tent ion from theJointBoard in its prewar plans, now emergedas a major objective in the mind of Ad-miral King. The other participants at theCasablanca meeting were too concernedabout more immediate problems to paymuch attention to King's remarks aboutthe Marianas, but the conferees did en-dorse planning for a drive through theCentral Pacificin 1943.

On 17 January the U.S. Joint StaffPlanners, a subcommittee of the JointChiefs of Staff, presented a fourfold pro-gram for the forthcoming year'soperationsin the Pacific: (1) seizure of the Solo-mons,ofeastern New Guineaas far as Laeand Salamaua, and of the New Britain-New Ireland area; (2) seizure of Kiskaand Agattu in theAleutians; (3) after thefall of Rabaul, seizure and occupation ofthe Gilberts, the Marshalls, and the Caro-lines through Truk, and extension of theoccupation of New Guinea to the borderof Netherlands New Guinea; and (4) op-erations in Burma designed to keep Chinain the war and increase the employmentof China-based aircraft against Japaneseshipping.17

be made for a campaign in the Aleutians,an advance northwest from Samoa alongthe Solomons-New Britain-New Ireland-New Guinea axis to protect the lineof communications between the UnitedStates and Australia, diversionary attacksagainst the Malay Barrier, and a CentralPacific advance west against the Truk-Guam line.18

TRIDENT ConferenceIn May of 1943 the President and

the Prime Minister with their CombinedChiefs of Staff convened again, this timein Washington at the TRIDENT Confer-ence.19 Most of the discussion again cen-tered around questions concerning theMediterranean theater and Burma andChina, but during the course of the meet-ing, the Combined Chiefs reaffirmed theirdetermination to get on with the war inthe Central Pacific.20

On 14 May the American representa-tives circulated to the Combined Chiefs apaper drawn up by the various subcom-mittees of the Joint Chiefs, entitled Strate-gic Plan for the Defeat of Japan.21 Thispaper was more of an estimatethanaplan,

18 CC S 170/2, 23 Jan 43, title: Final Rpt toPresident and Prime Minis ter Summariz ing Deci-sionsby CCS inCasablancaConf.19 For a more detailed discussion of the TRI-


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8 C A MPA IG N IN THE MARIANASbut it did articulate more clearly than be-fore th e main strategic principles endorsedby the highest U.S. planners for the warin the Pacific in 1943-44. It was assumedthat to bring about the unconditional sur-render of Japan it would first be necessaryfor the Allies to secure a foothold in Chinain order to makebest use of the enormousChinese manpower and to provide airbases from which to bomb the Japanesemainland. China could beenteredbythreeroutes: through Burma, through the Straitof Malacca and the South China Sea toHong Kong from the west, and across thePacific through the Celebes Sea to HongKong from the east. The British, withAmerican and Chineseaid,should be heldresponsible fo r operations along the firsttw o routes. The United States would as-sume major responsibility for the third.Next came the question of how Ameri-can forces could best get to the CelebesSea and Hong Kong from positions heldby the United States. The American plan-ners proposed atwo-pronged drivebyU.S.forces, one westward from Hawaii throughthe Central Pacific, the other west andnorth along the Solomons-Bismarck-NewGuinea line in General MacArthur'sSouthwest Pacific Area. The two thrustswere to merge in the Philippines-SouthChina Sea area and join in the descentupon Hong Kong. In determining priori-

ward advance should be made throughthe Central Pacific and a subsidiary roleassigned to the South and SouthwestPacific.

Onceagain Admiral King took the floorto press the argument in favor of the Cen-tral Pacific drive and more particularly tochampion his favorite project, the invasionof the Marianas. For years, he said, officersat the Naval War CollegeinNewport hadbeen studying the problem of supportingor recovering the Philippines as the sinequa non of defeating Japan. Their con-clusions all pointed to the route straightthrough the Pacific from th e Hawaiian Is -landsas the best approach. The Marianas,he insisted, were the key to the wes-tern Pacific. A major offensive there, heclaimed, would seriously jeopardize Japa-nese lines of communications, most prob-ably force theJapaneseFleetinto adecisivenaval engagement, and providebases fromwhich to bomb the Japanese home is-lands.22

In its final session at TRIDENT the Com-bined Chiefs of Staff, although not com-mitting themselves on the question of theMarianas, agreed to American recommen-dations for a two-pronged attack acrossth e Pacific. Specifically, they listed th efollowing strategic objectives in the Pacificfor 1943-44:1. Conducting air operations in and


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BACKGROUND OF STRATEGY 95. Intensification of operations againstenemylinesofcommunication.Two months later the Joint Chiefs ofStaff decided to modify the plans for

launching the Central Pacific drive. A di-rect assault on the Marshalls from Hawaii,they reasoned, would require more ship-ping and troops than were immediatelyavailable in the Central Pacific and mightnecessitate draining General MacArthur'sSouthwest Pacific Area of some of its re-sources. Also, it would be well to havebetter aerial photographs of the Marshallsbefore attempting the dangerous amphibi-ous assault on these Japanese strongholdsabout which almost nothing was known.Air bases from which photographic mis-sions could be flown should therefore bebuilt close to the Marshalls. Largely forthesereasons the Joint Chiefs, on 20 July,ordered Nimitz to capture Tarawa, in theGilberts, and Nauru as a preliminary togoing into the Marshalls themselves. Thetarget date selected was 15 November1943.23In August the Combined Chiefs, meet-ing at Quebec for the QUADRANT Confer-ence, accepted the revision as well as aschedule of operations proposed by theAmerican representatives for the periodafter the capture of the Marshalls. For theCentral Pacific this included the captureof Ponape, Woleai, and Truk in the Caro-

the Palaus or as a concurrent operation.24A fewdays after this decision was madeAdmiral Nimitz suggested one furtherchange in the plan for initiating the Cen-tral Pacific drive. He proposed substi-tuting Makin in the Gilberts for Naurubecause Makin could more easily be as-saulted and because it was closer to theMarshalls. The proposal was accepted,and Nimitz was authorized to seize Tara-wa, Makin, and Apamama in the Gil-berts.25 On 20 November 1943 simultan-eous amphibious landings were launchedagainst Makin and Tarawa by elementsof the 27th Infantry Division and the 2dMarine Division, respectively. Within fourdays both atolls were captured, followingwhich Apamama was occupied.26 TheCentral Pacific drive was under way.

General MacArthur s StrategyMeanwhile, halfway around the world

at his headquarters in Brisbane, GeneralMacArthur was developing strategic plansthat were not always consonant with theideas prevailing among high echelon plan-

24 JCS 446, 5 Aug 43, title: Specific Opns inthe Pacific and Far East, 1943-44; Min, 101stmtg JCS, 7 Aug 43; CCS 301/3, 27 Aug 43,title: Specific Opns in the Pacific and Far East;CCS 319/5, 24 Aug 43, title: Final Rpt to Presi-dent and Prime Minis ter .25 Msg, Nimitz to JCS, 260439, 26 Sep 43;


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10 CAMPAIGN IN THE MARIANASners in Washington. MacArthur, havingleft the Philippines in early 1942,was de-termined to return as quickly and with asstrong a force as possible. He was alsodetermined that the major role in thisundertaking should be assigned to theforces under his command and that themain approach to the Philippines shouldbe made through his own Southwest Pa-cific theater.

In early 1943 MacArthur's immediateconcern was with current operations lead-ing up to the eventual capture of Ra-baul.27 At the same time, his staff waspreparing a long-range plan (RENO I) fora return to the Philippines. As first setforth in February 1943, this plan calledfor the progressive seizure in New Guineaof Hansa Bay, Hollandia, Geelvink Bay,and the Vogelkop Peninsula. With thenorth coast of New Guinea under control,Southwest Pacific forces would then ad-vance north to Halmahera or to the Cele-bes before the final jump into the south-ernPhilippines.28This schedule of operations expressedperfectly MacArthur's fundamental strate-gic ideas. The Philippines could best beapproached by a series of amphibiousjumps along the entire northern coast ofNew Guinea, each so distanced as to per-mit full cover by land-based aviation. Asimilar move into Halmahera or to the

Arafura Sea,he would be fully preparedtomakegood hispromisetoreturn.Preoccupied as he was with his owntheater, MacArthur could only view withalarm thegrowingpressurefor an advancethrough the Central Pacific. The JointChiefs of Staff and the Combined Chiefsof Staff notwithstanding, he strongly op-posed an invasion of the Marshall Islands.Even after the Combined Chiefs had ap-proved and authorized theMarshalls oper-ation, he radioed General Marshall:

From a broad strategic viewpoint I amconvinced that the best course of offensiveaction in the Pacific is amovementfrom Aus-tralia through New Guinea to Mindanao.This movement can be supported by landbased aircraft which is utterly essential andwill immediately cut the enemy lines fromJapan to hisconquered territory to the south-ward. By contrast a movement through themandated islands willbe a series ofamphibi-ou s attacks with the support of carrier basedaircraft against objectives defended byNavalunits and ground troops supported by landbased aviation. Midway stands as an exam-ple of the hazards of such operations. More-over no vital strategic objective is reacheduntil the series of amphibious frontal attackssucceed in reaching Mindanao. The factorsupon which the old Orange plan were basedhave been greatly altered by the hostile con-quest of Malaya and the Netherlands EastIndies and by the availability of Australia asa base . . . .2 9

This protest may have helped persuade


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BACKGROUND OF STRATEGY 11Quebec meeting of the Combined Chiefsof Staff (QUADRANT), it was decided,against General MacArthur's previous ad-vice, to bypass Rabaul,31 These decisionson thepartof higherauthoritydid nothingto dissuade the Southwest Pacific com-mander from continuing his opposition toan extension of the Central Pacific drive.Specifically, he was strongly set against aninvasionof theMarianas.32

Enter theArmyAirForcesIn the autumn of 1943 a new factorentered into the strategic picture of the

war against Japana factor that was tohave an important bearing on the decisionto invade the Marianas. The Army AirForces announced the imminent appear-ance of a very long range bombertheB-29.An experimental model of the plane wasfirst flown in September 1942, but it tookabout another year to iron out the "bugs"and make arrangements for quantity pro-duction. From the point of view of strate-

gic bombing, the outstanding characteris-tic of this four-engine plane was that witha bomb load of four tons it had an esti-mated range of approximately 3,500miles.In effect, once the B-29 was produced insufficient quantity, mass bombing raidscould be conducted from friendly air basesagainst enemy targets located as much as1,750 miles away, although fo r optimumefficiency and safety a 1,500-mile radiuswas usually used as a basis for calcula-tion.33As 1943 drew to a close, it became ap-parent that the B-29's would not be offth e production line in sufficient numberin time to play a significant role in thepreinvasion bombardment of Europe, andthat in any case the B-17's and B-24'salready assigned to the European theaterwere adequate for the job there.34 Thequestion then arose as to how the B-29'scould best be employed against Japan. Towhich of the varioustheaters of operationsin the Pacific and Far East should thebulk of the bombers be assigned? Threepossibilities suggested themselves: Austra-lia, China, and the Marianas.

From the Southwest Pacific came ur-gent representations by Lt. Gen. GeorgeC. Kenney of the Fifth Air Force that firstpriority in the allocation of the new bomb-ers be assigned to his command. He ar-gued that th e best way of using th eB-29's

31 JCS 446; Min, 101st mtg JCS; CCS 301/3;and CCS 319/5. All cited n. 24. MacArthur's op-position to bypass ing Rabaul was strongly put ina radio to Marshall, C4183, 23 Jul 43, CM-IN16149.

32 General MacArthur reiterated his oppositionto the invasion of the Marianas as late as 1955.He stated, "The 'Central Pacific Concept' . . .lost its validity when it was abandoned in favor


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12 CAMPAIGN IN THE MARIANAStroleum industry in the Netherlands Indiesfrom bases in Australia. In Washington,however, the Air Forces chief, GeneralArnold, and his staff had other ideas, andKenney's suggestionwasrejected.35At the Quebec conference of August1943 General Arnold presented to theCombined Chiefs his "AirPlan for theDefeat ofJapan."36 Arnold estimated thatby October 1944ten B-29 groups oftwenty-eight planes each might be avail-able for employment against Japan. It wasassumed that by that time no Pacific is-land within fifteen hundred miles of theJapanese main island of Honshu wouldhave been captured. Therefore he pro-posed to build a chain of airfields northand south of Changsha in China, all ofwhich would be within the required rangeof most of Japan's war industries. Sincethe Air Forces high command refused tobelieve either that a port on the east coastof China could be captured in time tosupply these operations or that the BurmaRoad could be opened, it concluded thatlogistical support of any airfield built inChina must come from India, flown overthe HumpinB-24's.37

Air Forces planners were none toohappy about basing their new bombers inChina, partly because of the logistical dif-ficulties involved and partly because they

conference, they urged that the Marianasbe seized and that D Day for the opera-tion be advanced to mid-1944 by neutral-izing and bypassing intervening Pacific is-lands.39 The Air Forces planners arguedstrongly that "plans for the accelerationof the defeat of Japan would place em-phasis upon the seizure of the Marianasat the earliest possible date, with the es-tablishment of heavy bomber bases as theprimary mission."40 The Marianas, itwill be recalled, were about 1,270 milesfrom Tokyo, well within the estimated op-timum 1,500-mile cruising radius of theB-29's.

Cairo ConferenceAt last Admiral King had a powerful

ally in his persistent campaign for an in-vasion of the Marianas. At the meeting ofthe President and Prime Minister with theCombined Chiefs in Cairo in December1943 (SEXTANT), the joint Navy-AirForces efforts bore fruit . Among the oper-ations submitted to and approved byPresident Roosevelt and Prime MinisterChurchill was the "seizure of Guam andthe Japanese Marianas," tentatively set for1October 1944.

This operation was to follow the captureof important objectives in the Marshalls


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BACKGROUND OF STRATEGY 13move on to the tip of Vogelkop PeninsulabyAugust 1944.41The Combined Chiefs chose this occa-sion to again endorse the Central Pacificroute as part of a two-pronged drive toJapan. In presenting their "Overall Planfor th e Defeat of Japan," they stated thattheir ultimate aim was "to obtain objec-tives from which we can conduct intensiveair bombardment and establish a sea andair blockade against Japan, and fromwhich to invade Japan proper if thisshould prove necessary." This would ne-cessitate one advance along the NewGuinea-Netherlands Indies-Philippinesaxis and another through the Central Pa-cific in time for a major assault in thearea of Formosa-Luzon-China by thespring of 1945. The two lines of advancewere to be "mutually supporting," butshould there be conflicts, "dueweightshould be accorded to the fact that opera-tions in the Central Pacific promise at thistime a more rapid advance toward Japanand her vital lines of communication; theearlier acquisition of strategic air basescloser to the Japanese homeland; and, ofgreatest importance, are more likely toprecipitate a decisive engagement with theJapanese Fleet."42 Here in a capsule wasthe rationale of the Central Pacific con-cept of strategy.

Central Pacific. A preliminary draft of hiscampaign plan, GRANITE, was finished by27 December. It tentatively outlined oper-ations asfollows:43

Capture ofKwajaleinKavieng(and a i rattackonTruk)ManusEniwetokMortlock (NomoiIs.)TrukSaipan,Tinian,

and Guam

Date31January194420March 1944

20April 19441May 19441July 1944

15 August 194415November 1944On 13 January, Nimitz issued another

GRANITE plan revising his original some-what.44 Operations to seize Mortlock Is-land and Truk were scheduled for 1 Au-gust. The possibility of bypassing Trukwas considered, and it was suggested thatif Truk could be bypassed, the Palausshould be invaded by Central Pacificforces on 1 August. The Marianas couldthen beinvaded by 1November since cap-ture of the Palaus, it was assumed, wouldbe a less costly an d time-consuming ven-ture than assaulting the Japanese strong-hold on Truk. In any case, both theoriginal plan and the revision looked tothe Marianas as the culmination of the1944campaign.


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14 CAMPAIGN IN THE MARIANASHarbor in the last days of January 1944.Present, amongothers,wereAdmiral Nim-itz, and from his staff, Rear Adm.CharlesH.McMorris,Rear Adm. ForrestP.Sher-man, and Vice Adm.John H. Towers,Commander, Air Force Pacific. From theSouthwest Pacific came M aj. Gen.Rich-ard K. Sutherland, MacArthur's chief ofstaff; General Kenney, Commander, Al-lied Air Forces, Southwest Pacific Area;and ViceAdm. ThomasC. Kinkaid, Com-mander, Allied Naval Forces, SouthwestPacific Area.45

Admiral Nimitz presented his revisedGRANITE plan for the consideration of theconferees. Immediately, and from all sides,objections were voiced to the proposal toinvade the Marianas. General Sutherlandadvocated pooling all available resourcesin the Pacific and concentrating uponoperations in MacArthur's theater. "IfCentral Pacific will move against Palau asthe next operation after the Marshalls,"he argued, "andmake available to South-west Pacific Area the amphibious forcenow contemplated for Truk, we can takeall of New Guinea, the Kai and Tanim-bars, and Halmahera in time to join youin amphibious movement to Mindanaothis year." General Kenney spoke ofbombing Japan by B-29's based on theMarianas as "just a stunt." Admiral Kin-kaid remarked that "anytalk of the Mari-

46

astic over the Marianas, although Nimitzhimself favored the project. Admiral Mc-Morris doubted if long-range bombingfrom the Marianaswould cause the capit-ulation of Japan. Admiral Sherman ad-mitted that operations in the Marianaswould be extremely costly and that whencaptured the harbors would be of limitedusefulness to the Navy.

Whenword ofthese proceedingsreachedAdmiral King, he read them "with indig-nant dismay." In a stern message to Nim-itzhe pointedout, "Theidea of rolling upthe Japanese along the New Guinea coast,through Halmahera and Mindanao, andup through the Philippines to Luzon, asour major strategic concept, to the ex-clusion of clearing ou r Central Pacific lineof communications to the Philippines, isto me absurd. Further, it is not in accord-ance with the decisions of the Joint Chiefsof Staff. Assuming correctly that Nimitzagreed with his own strategic ideas, hecontinued, "I'mafraid . . .that youhavenot . . .maintained these views sufficient-ly positively vis-a-vis the officers from theSouth and Southwest Pacific,"47 AdmiralKing was not one to stand idly by whiletheater staffs undermined his favorite andlong-nourished war plan almost at theverymomentof itsfruition.


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BACKGROUND OF STRATEGY 15shalls was occupied without a battle.48The conquest of these important positionshad been relatively easy, and the reservetroops intended for the operation had notbeen committed. Nimitz could thus speedup his plan for moving into the westernMarshalls, and accordingly he launched,on order, an amphibious assault againstEniwetok on 17 February, two monthsahead of schedule. At the same time hedelivered a carrier strike against Truk.49Eniwetok fell in sixdaysbefore the com-bined assault of the 22d Marines and the106th Regimental Combat Team of the27th Infantry Division. On 17-18 Febru-ary (Tokyo t ime) Rear Adm. Marc A.Mitscher's Fast Carrier Force struck theonce mighty Japanese bastion at Truk,destroying at least seventy planes on theground and in the air and about 200,000tons of merchant shipping in the harbor.50The defenses of Truk were so weak as tolend strong support to the idea that itmight bebypassedaltogether.Shortly after th e successful conclusionof these operations in the Central Pacific,General MacArthur found opportunity tostep up his own schedule. The most re-cently approved planscalledfor the South-west Pacific Area commander to conductsimultaneous invasionsof Kavieng on New

Ireland and Manus in the Admiralties on1April.51 Then, on 23February, an inci-dent took place that persuaded MacAr-thur that he could safely accelerate atleast part of this plan. Planes from theSouthwest Pacific flying over th e Admiral-ties on that date reported no evidence ofthe enemy. The general decided to act atonce. He dispatched elements of the 1stCavalry Division to LosNegrosto conducta reconnaissance in force and,when ini-tial resistance was discovered to be light,sent the rest of the division in to capturetheentire Admiraltiesgroup.52

Washington Planning ConferencesFebruary-March 1944

In the light of these events, the timehadobviously come for the Washington plan-ners to reconsider their schedule of opera-tions fo r both Pacific theaters for the restof 1944.

Most planners by this time agreed thatthe primary objective for the next phaseof the war against Japan was to establisha lodgment somewhere in the "strategictriangle" represented by Luzon, Formosa,and the neighboring China coast. Fromthere it was believed that communicationsbetween the Japanese homeland and theNetherlands Indies could be completelycu t off,bases for the very long range48 See Crowl and Love, Gilberts and Mar-shalls, pp. 302-04; Lt. Col.Robert D. Heinl, Jr.,


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16 CAMPAIGN IN THE MARIANASBeyond this point agreement ceased.

The arguments that ensued were manyand various, but they can be resolved intotwo main issues.First, which was thebetterroute of approach to the strategic triangle,the Central Pacific route through themandated islands or the Southwest Pacificroute along the coast of New Guinea toMindanao? Second, which of the twotheaters would be given priority in theallocation of resources, especially thosetroops, ships, and aircraft that had untilnow been assigned to the South Pacific, acommand that had practically completeditsmissionand was about tobecomea reararea?

Early in February Admiral Shermanfrom Nimitz' staff and General Suther-land, MacArthur's chief of staff, appearedin Washington to represent their respec-tive commanders in the discussions thatthe Joint Chiefs of Staff and their subor-dinate committees were to hold, Suther-land argued that RENO and GRANITEplans were "relatively weak and slow ofprogress." As a substitution, he proposed"an advance along the general axis, NewGuinea-Mindanao, with combined forces."Truk, he believed, could be bypassed and,with "thecapture of Truk thus obviated,amphibious forces can be combined for anadvance along the northern coast of NewGuinea." This, he claimed, would enable

hope that Admiral Halsey will be assignedas Commander, Allied Naval Forces, be-cause of his ability, rank,prestige, and ex-perience."53

From General MacArthur himself camerepresentations of the same nature. ToGeneralMarshallhe radioed:

There are now large forces available in thePacific which with th e accretions scheduledfo r the current year would permit the execu-tion of an offensive which would place us inthe Philippines in December if the forceswere employed in effective combination.However, under the plan of campaign thathas been prepared in Washington, the forceswill be employed in two weak thrusts whichcan not at tain th e major strategic objectiveunt i lseveral months later . . . .54

In the same message MacArthur in-sisted that the forces of the South Pacificshould remain under his command. Theseforces, he argued, had been engaged inoperations within his own theater sincetheiradvance from Guadalcanal. He couldnot continue to operate effectively with-out them. "I must state," he added, "thatany reduction in the forces presently en-gaged in the Southwest Pacific by actualwithdrawal of forces of any categorywouldbeincomprehensible."55

At the same meeting of the Joint Chiefsof Staff addressed by General Sutherland,Admiral Sherman attempted to explainNimitz' Plan GRANITE. The plan, he


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BACKGROUND OF STRATEGY 17Carolines about 1 August, and the Mari-anas, or such other point as might be se-lected as the next objective, by the end oftheyear."56

MacArthur's chief antagonist in thisstrategic debate was neither Sherman norNimitz,but,as usual, Admiral King. Kingvigorously opposed handing MacArthurthe naval forces of the South Pacific. Mac-Arthur already had the Seventh Fleet un-derhiscommand ,Kingargued. The SouthPacific forces were operating in a separatearea and were prima rily concerned insuch circumstances with the probability ofenemy forces from th e Pacific Ocean Areasthreatening the operations of both theSouth and Southwest Pacific. King couldsee no sound reason for placing them un-der MacArthur.57 He called attention tothe decision of the Combined Chiefs ofStaff at Cairo (SEXTANT) that the ad-vance in the Pacific should be along twoaxes and that in case of conflicts betweenthe two, "due weight should be accordedto the fact that operations in the CentralPacific promise at this time a more rapidadvance toward Japan and her vital lineof communications."58 "General MacAr-thur," said King, "has apparently not ac-cepted this decision and desires a commit-ment to an advance along a single axis. Ido not think that this is a propitious timetochangeour agreedstrategy."59

manders. Specifically, Marshall recom-mended that the Joint Strategic SurveyCommittee, which consisted of Vice Adm.Russell Willson ( N a v y ) , Lt. Gen.StanleyD . Embick ( A r m y ) , and Maj. Gen.MuirS. Fairchild (Army AirForces), be direct-ed to study the matter anew and report itsviews as to what geographic objectivesshould be seized, the order of their seizure,an d whataxisof advanceappeared to offerth e best chance fo r victory in the Pacific.60Admiral King immediatelyconcurred.61

To the disappointment of the advocatesof the Southwest Pacific concept of strat-egy, th e Joint Strategic Survey Committeecame forth with a statement clearly favor-ing King's and Nimi tz ' strategic plan.62The committee, repeating its earlier con-victions, stated that th e Joint Chiefs ofStaff "should resolve th e present situationas between these tw o plans by decidingand directing that the primary effortagainst Japan will be made through theCentral Pacific, with operations in theSouthwest Pacific cooperating with andsupporting that effort. The primary ob-jective, said the committee, was theFormosa-Luzon-China triangle, and thatobjective "would seem to be more effec-tively supported by the Central Pacificconcept than by the concept of the South-west Pacific. The former leadsmost direct-ly and most promptly to the vital Formosa,


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18 CAMPAIGN IN THE MARIANAStensive operations before reaching thatvitalarea."63

The Joint Strategic Survey Committeereport not only disappointed the represent-atives of the Southwest Pacific but alsofailed to satisfy General Marshall, He didnot feel that the committee had sufficient-ly explored the problem of allotting re-sources between the two theaters or thequestion of how best to employ the greatAllied superiority in land-based air.64 Hewanted other subcommittees of the JointChiefs, specifically the Joint Staff Plannersand the Joint Logistics Committee, tostudy the matter further.65 In reply tothese proposals, Admiral King, whileagreeing in principle that further long-range studies would be beneficial, ex -pressed his fear that any more delays incommittee might kill the momentum of thedrive nowunder way in the Pacific.66With Admiral King pressing fo r imme-diate action either in the direction ofTrukor straight for the Marianas or the Palaus,General MacArthur on 5 March cameforward with a proposal to accelerateoperations in his own theater. He advisedtheJoint Chiefs of Staff to omit the HansaBay operation scheduled for about 22April and to move instead to Hollandia,some three hundred miles up the coast ofNew Guinea. To accomplish this, he pro-posed to use not only the forces of the

also Central Pacific aircraft carriers andother shipping tentatively earmarked tosupport the Kavieng-Manusoperation.67

These suggestions were in keeping withGeneral MacArthur's latest RENO plan,which reached Washington within a fewdays. It proposed a four-phase program:first, a continued advance along the northcoast of New Guinea through Hollandiato Geelvink Bay;second, establishment ofair bases in the Arafura Sea area for stra-tegic bombing in the Netherlands Indiesand to support subsequent operations intothe Vogelkop and Halmahera; third, seiz-ure of the western tip of the Vogelkop andHalmahera; and fourth, occupation ofMindanao, southernmost of the Philip-pines, and the establishment of bases therefor an attack upon the Formosa-Luzon-China coastarea.68Admira l Nimitz, who had meanwhilebeen summoned to Washington, wasquickto note that these proposals, if accepted,would have the effect of slowing up opera-tions in his own theater. To the JointChiefs he argued that a retention byMac-Arthur of forces from the Central Pacificafter the capture of Kavieng and Manuswould result in "stopping the Central Pa-cific Campaign, losing its momentum, de-ferring movement into the MARIANASuntil th e approach of the typhoon season,


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BACKGROUND OF STRATEGY 19FORMOSA-CHINA area in early 1945asnowplanned."69On the affirmative side, Nimitz sug-gested tw o alternative schedules for theremainder of 1944. The first contemplatedan invasion of Truk on 15 June, thesouthern Marianas on 1 September, an dthe Palaus on 15 November. The secondproposed bypassing Truk and going intothe southern Marianas on 15June, Woleaion 15 July, Yap on 1September, and thePalaus on 1 November. On reconsidera-tion, Nimitz decided that, if the secondschedule were accepted, the capture ofYap could be deferred until th e Palaushad been taken and that a fleet harborcould be established in Ulithi. This wouldadvance the target date for the Palaus to1 October.70In the end, the Joint Chiefs of Staff ac -cepted neither MacArthur ' s nor Nimitz'schedules in toto. Nor did they acceptwithout change the final conclusion of theJoint Strategic Survey Committee that toseizethedesired objectivein theFormosa-Luzon-China coast area, "a fundamenta lstrategicprerequisite is our control of theMarianas, Carolines, Palau [Pacific]Ocean area."71 At the insistence of Gen-eral Marshall, Mindanaowasadded to thevital intermediate objectives that UnitedStates forces must capture before proceed-ing on to thestrategictriangle.72

Thus the directive that the Joint Chiefsof Staff issued to General MacArthur andAdmiral Nimitz on 12 March representedin a sense a compromise between the Cen-tral Pacific and the Southwest Pacific con-cepts of strategy. It declared "that themost feasible approach to the Formosa-Luzon-China area is by way of Marianas-Carolines-Palau-Mindanao area, andthat the control of the Marianas-Carolines-Palau area is essential to the projectionof ou r forces into the former area, andtheir subsequent effective employmenttherefrom. Specifically, th e Joint Chiefsordered:

1. Cancellation of the Kavieng opera-tion and the complete isolation of theRabaul-Kavieng area with the minimumcommitment of forces.

2. Early completion of the occupationof Manus and its development as an airan d fleetbase.3. Occupation of Hollandia by Mac-Arthur ,target date 15April 1944.4. Establishment of control of the Mari-anas-Carolines-Palau area by Nimitz 'forces by neutralizing Truk; by occupyingthe southern Marianas, target date 15June 1944; and by occupying the Palaus,target date 15September 1944.

5. Occupation of Mindanao by Mac-Arthur's forces supported by the Pacific


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20 CAMPAIGN IN THE MARIANASprepare their tactical plans in detail. Thesouthern Marianaswould be assaulted andthe target date was to be 15 June. The

largest amphibious operation yet to beundertaken in the Pacific was about toget underway.


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The MarianasIn History

The islands thus chosen as the nextpoint of American amphibious assault inthe Central Pacific had had a long andnot altogether happy experience as minorpawns in the international rivalries ofgreat powers. Magellan discovered them in1521 in the course of his famous first voy-age around the world. Struck by the sail-in g powers of the native boats and by thesimilarity of their rigging to that of thesmall craft that abounded in his own Med-iterranean,thenavigatorlabeledhisdiscov-eries, "Islas de los Velas Latinas" (Islandsof the Lateen Sai ls) . Other members ofthe expedition were more impressed bythe natives' pilfering habits and according-ly called them "Islasde losLadrones" (Is-lands of the Thieves), a name that re-mained in popular usage well into thetwentieth century, even though it had longsince been officially abandoned. Late inth e seventeenth century the islands wereofficially renamed "LasMarianas" inhonor of Maria Anna of Austria, wife ofPhilip IV and Queen of Spain, who took

interest

The original native population of theMarianas, the Chamorros, were a hardyrace, probably of Polynesian origin, butnot hardy enough to withstand the en-croachments of western civilization as rep-resented by Spanish traders and mission-aries. In spite of mass baptisms by the lat-ter, native resentment toward the rigidrule of the priesthood increased until final-ly, in the 1960's, armed revolution brokeout in the islands. The result was inevit-able; the Spaniards with their superiorweapons and organization overcame therebels, killed large numbers and forcedmost of the remainder to flee. The centerof the trouble was on Guam, and fromthere many of the remaining Chamorrosfled to the northern Marianas, where theywere relentlessly pursued and persecuted.Others finally escaped south to the Caro-lines to become intermingled with theKanakapopulationofthoseislands.

Spanish control, which had become pro-gressively weaker during the nineteenthcentury, was finally severed completely in1898-99. Imperial Germany was the first


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22 CAMPAIGN IN THE MARIANASish hegemony in Micronesia.2 In August1885 the Germans hoisted their flag overYap in the western Carolines and laidclaim to much of the surrounding terri-tory. After violent Spanish protest, thedisputewas submitted to papal arbitrationand Spain's sovereign rights were con-firmed, although Germany obtained im -portant commercial concessions at thesame time. Negotiations fo r transfer be-tween the two countries continued in the1890's, and in 1899 Spain ceded all ofher possessions in the Carolines, the Mar-shalls, and the Marianas to the GermanEmpire for the sum of about $4,000,000.Meanwhile, a small American naval expe-ditionary force had seized Apra Harboron Guam, and at the termination of theSpanish-American war that island wascededto the UnitedStates.

Another radical change in the disposi-tion of the entire Central Pacific area oc-curred as the result of World War I.Japan, having emerged successfully fromher recent war against Russia and beinganxious to expand her commercial andmilitary influence throughout the Orientand itsadjacent waters, was quick to seizethe opportunity of a European war torealize her own imperialist ambitions. Asone of the Allied Powers, Japan contribu-ted her share to the ultimate downfall ofthe German Empire by seizing the Caro-

still remained under League of Nationsauthority. During the 1920's and 1930'sthe Japanese proceeded vigorously to col-onize these new holdings and to exploittheireconomicresources or thebenefit ofJapanese economy. After 1935, when Ja-pan withdrew from the League of Nations,no further effort was made to give evenlip service to the idea that th e islandswere mandated territories. They became,to all intents and purposes, outright pos-sessions.3

Meanwhile, the United States had oc-cupied Guam and had converted it into aminor naval base. By an executive orderof President William McKinley dated 23December 1898, the island was placed un-der control of the Navy Department, anaval officer was commissioned asgovernorof Guam, and the same officer was ap-pointed by the Secretary of the Navy ascommandant of the naval station, whichencompassed the entire island. Progress inconstructing a naval base of respectableproportions was slow and halting. In 1939the Hepburn Board reported to Congressthat the area should and could be devel-oped into a major naval base, but the nec-essaryappropriationsfailed topass.

The Japanese Invasion ofGuamAt the t ime of the outbreak of war be-


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TH E M A R I A N A S 23trol craft and an old oiler. One of thepa t ro l c ra f t , the USS Penguin, m o u n t e dtwo 3-inch ant ia ircraft guns and the oilerboasted two .50-caliber antiaircraft ma-ch ine guns.4

Japanese designs against this t iny forceand the outpost that it garrisoned beganto mater ia l ize well before the attack onPearl Harbor. As early as the m idd le ofOctober 1941, the18thAir Unit, a smal lforce of reconnaissance seaplanes based inthe Marianas, began conduct ing a recon-naissance, of G u a m and d u r i n g the follow-ing N o v e m b e r flew f r e que n t secret photoreconnaissance miss ions over the island ata l t i tudes of 3,000 meters or h i g h e r .5 A tthe same t ime, small Japanese vesselsbeganpa t ro l l ing the wa te r s a round the i s land ,mostly at night, and in early Decembersucceeded in l a n d i n g several native Guam-anians f r iendly to t h e i r cause.

Japanese p la ns for an a m p h i b i o u s inva-sion of G u a m were complete by 8 Novem-ber. On t h a t date M a j .G e n . TomitaraHori, who commanded the South SeasDetachment, a uni t of about 5,500 Armytroops, received his orders . He was to as-semble his forces in the Bon ins in Novem-

ber and wait there unti l definite word ofthe first Japanese air attack against theUni te d States had been received. Then,nava l air units based on Saipan were tofl y to Guam and attack U.S. ships and in-sta l la t ions. Meanwhile, Army troop trans-ports wi th a naval escort were to proceedfrom the Bonins to G u a m , where landingopera t ions would c omme nc e in the earlym orn in g of 10 December. In addition tothe A r m y troops assigned, the N a v y wasto contribute a special landing force ofabou t 400 men d r a w n from the 5th De-fense Force stationed onSaipan.6The planes assigned to softening up thetarget came, to about twenty in number,i n c l u d i n g the 18th Air Unit, which hadbeen busy on reconnaissance missions overth e island since October.At 0525 on 8 De-cember word came to the airmen waitingon Sa ipan that the Greater East Asia Warhad begun. The message read, "Begin at-t ack on Guam i mmed i a t e l y . 7 The shoot-ing war in the M a r i a n a s had started. Itwould not formally end for another twoyearsand n inemonths.W i t h i n three hours of receiving thiscommand, Japanese planes bore down onG u a m and bombed the American oilerBarnes in the harbor . Next they turnedtheir a t t en t ion to the patrol boat Penguin,which was at tempting to escape to theopen sea,and finally they dumped their

4Capt G. J. M c M i l l i n , U S N ,to CNO, 11 Sep4 5 , s u b :S u r r e n d e r a t G u a m to the J a p a n e s e ;ONI 99, p . 2; JICPOA Bul l 52-44, 15 Apr 44,Guam, p. 6; His to r i ca l D i v i s i on , War Depart-m e n t , Guam: Operations of the 77th Division (21July-10 August 1944), A M E R I C A N FORCES


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24 CAMPAIGN IN THE MARIANASthe extent that she had to be abandoned.A second flight appeared over the islandat 1330 the same afternoon, the planesconcentrating their attack on the still un-sunk Barnes and the cable and wirelessstationsashore.

The following day Japanese a ircraf tagain made morning and afternoon raids.Two bombs struck the Marine barracks,and many other hits were scored. TheJapanese airmen reported that fire fromth e ground was very light and that theyhad spotted no artillery emplacements andno mines in any of the harbors or baysonly a machine gun position in the north-ern suburbs ofAgana. (SeeMap V

While Guam burned under the bombsof its attackers during the first two daysof the war, the troop-laden assault vesselsand their escorts were on the way downfrom the north. At 0900 on 4 December,the main elements of the convoy, carryingthe 5,500 Army troops, moved out ofHahajima and headed toward Rota,where they were joined by the ships carry-ing the small naval de tachment from Sai-pan. From Rota the force advanced inseparate groups to Guam, where all ar-rived during the first hour of 10 Decem-ber. Landing operations commenced at0230. The main force of the Army troopslanded on the west coast between Facp i

The naval detachment landed abouttwo miles north of Agana. As it advancedtoward the city, it flushed the machinegun emplacement, reported by planes thenight before, about one ki lometer from thecity itself. The main body of the U.S. marines had taken positions at the Marinerifle range on Orote Peninsula, and onlyabout eighty G u a m a n ia n s and a fewAmericans were in Agana when th e Japa-nese arrived. These few put up a stifffight and twice at Agana Plaza drove th einvaders back with rifle and machine gunfire before finally being overcome. Afterth e skirmish on the plaza, the Japanesewent on to occupy th e naval hospital andth e wireless station, and the naval repairstation at Piti. Finally, at 0545, the islandgovernor, Capt. C. J. McMill in, USN,realized that resistance was useless andcommenced negotiations for surrender.Soon after, th e American ensign was rundown from Government House and re-placed by the Imperial flag of Japan. TheJapanese had completed the occupation oftheMarianas chain. 8

Description of the IslandsThe Marianas are a chain of volcanic

islands runn ing in an approximately north-south direction from 20 32 N, 144
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26 CAMPAIGN IN THE MARIANASThe four largest islands and those havingthe chief military utility are all in thesouthern half of the chain. These, fromnorth to south, are Saipan, Tinian, Rota,and Guam. (Map 2) Of these, Rota waseliminatedby the U.S. planners as a feasi-ble target because of the inaccessibility ofmost of its coast line, its inadequate har-bor facilities, and its general inferiority tothe other three islands as a naval and airbase for future operations against Japan.

Saipan, Tinian, and Guam lay directlyathwart or on the near flank of the ad-vance of Central Pacific forces from theirwesternmost base at Eniwetok to almostany part of Japanese-held territory thatmight become the object of future amphi-bious operationsthe Philippines, Formo-sa, the Volcano Islands, the Ryukyus, andJapan proper. Saipan lies about a thou-sand nautical miles west of Eniwetok andover3,200milesfromPearlHarbor.North-west, Tokyo is only about 1,260 miles dis-tant,and ManilaBay is1,500miles almostdue west. Tinian is just three miles southof Saipan; Guam, approximately anotherhundredmilesin asoutherlydirection.

The main geographic factors that plan-nersof the operation had to take into con-sideration were climate, the location ofbeaches and the approaches thereto, to-pography of the terrain inland from thebeaches, the nature of the vegetation as it

The first aerial photographs of Saipanand Tinian were taken on 22 and 23Feb-ruary 1944 by planes flown from MarcMitscher's fast carrier force (Task Force58) . At that time, a total of twenty-fivesorties at various heights and angles wasflown, but because of cloud formationsonly a partial coverage of the islands wasobtained.9 These were supplemented byfull photographic coverage provided by aflight of five Navy PB4Y's, escorted byArmy bombers, that took off from Eniwe-tok on 18 April for a round trip of morethan two thousand miles and thirteenhours in the air, Asecondmission flown bya similar group of planes on 25April alsophotographed Guam.10 Guam was cov-ered again on 7 May by six Navy photo-graphic "Liberators," and the northernislands as well as Guam were rephoto-graphedon 29May.11In addition, the submarine USS Green-ling made a series of sorties around allthree islands between 2 and 29 April andobtained excellent photographs, whichwere made available to the expeditionarytroops. The submarine's photographs werechiefly remarkable fo r their accuracy ofdetailon thebeachapproaches.12Between 15January and 10 May, JointIntelligence Center, Pacific Ocean Areas(JICPOA), issued a total of eight infor-

9Hq Expeditionary Troops, Task Force 56 Re-


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THE MARIANAS 27mation bulletins covering the proposed is-land targets,13 In addition, the Office ofNaval Intelligence ( O N I )made availablea monograph on the geography of the Pa-laus and the Marianas that had been pre-pared in the spring of 1942.14 More de-tailed wasanother ONI bulletin on Guamthat was an exhaustive, although some-what obsolete, study based chiefly on amonograph completed by Marine CorpsSchools in Quantico as early as 1937 andthe notes and personal recollections of anaval officer, Comdr. R. F. Armknecht( C E C ) ( U S N ) , who had left the islandonlya month before theJapanesecapturedit.15 Other materials, including diagramsof tides,sunlight and moonlight tables,andcaptured Japanese charts, completed thelist of information on the Marianas uponwhich plans for the landings had to bebased.16Some of this proved to be inaccurate indetail. The number of enemy installationsand the size and disposition of troopsweregenerally underestimated. Many terrainfeatures were erroneously depicted in themaps made on the basis of photographicintelligence. On the whole, however, afairly good general understanding of thenature of the targets could be gleanedfromthe various sources.

Climatic conditions vary little as be-tween the sister islands of Saipan and

Tinian in the north and Guam in thesouth. The year can be conveniently di-vided into tw o seasons: the dry or wintermonsoon season from November throughMarch, and the wet or summer monsoonseason from April through October. Dur-ing most of the dry period the prevailingwind is from north and east with an aver-age velocity of ten to fifteen knots. ByJune th e wind usually shifts from east tosouth and by August and September thesouthwestern monsoon frequently occurs.Thus, if landings on the western beacheswere to be considered, it was clear thatthey should be made before August in or-der to be certain of a leeshore.

Averagecloudcover is nearly 70percentfor most of the year, which added to theproblem of achieving adequate aerial ob-servation and aerial reconnaissance. Gen-erally, however,weather conditions offeredno serious obstacle to military operations.The climate is mild and healthful. Meantemperature on Saipan varies between aJanuary maximum and minimum of 81F. and 72 F., respectively, and June val-ues of 85 F. and 75 F. Guam, being ahundred miles closer to the equator, issomewhat warmer and more humid butnot enough so to make any significant dif-ference. The summer months constitutethe rainy season, during which the totalprecipitation isfrom 80 to 86 inches. Most


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28 CAMPAIGN IN THE MARIANASfully developed. About once every tw oyears disturbances of the typhoon type hitthe islands or pass near enough to causeviolent winds and heavy rainfall, but evenso the storm diameter is generally com-parativelysmall.17

None of the three islands offered idealbeach conditions for landing assaulttroops. On Saipan the land on thewesternsideslopesrather gently up from the shoreline, but the beaches themselves could bereached only with difficulty because offringing and barrier reefs that extend formost of the is land's length. (See Map I.)A small gap existed in the reef just off thetown of Charan Kanoa and a dredgedchannel led intoTanapag Harbor, but formost of the area the coral barrier present-ed a serious impediment to the landing oftroops boated in small craft. The northend and east side of the island have deepwater close inshore and are free of reefsexcept for a fringing one around Magi-cienne Bay on the east coast. However,the beaches were generally narrow and theshores steep, thus making landing opera-tions and movement inshore extremelyhazardous. The same conditions prevailedfor the most part on the southern end.

Harborage facilities ranged from poor tomediocre. Tanapag Harbor, the principalanchorage area,was the onlyonethat pro-vided even partial protection from all

roadstead, and landing and unloadingwould be impossible during strong wester-ly winds. The only shelter against norther-ly and westerly winds was at MagicienneBay on the southeast coast. However, thebay was deep and open to winds and seasfrom thesoutheast.18Tinian was even better equipped topo-graphically to resist an amphibious land-ing. The main obstacle to invasion was analmost unbroken barrier of abrupt cliffsclose to the water line and ranging froma fewfeet to overahundred feet inheight.Although the cliffs were not unscalable,especially along the northern and westernshores, there was very little landing spaceat thewater's edgefor small craft, and theflow of supplies inland from such narrowbeaches would be seriously handicapped.The cliffs were broken at various spots inthe neighborhood of Tinian Harbor andagain on the northwest coast and alongthe northeastern shore line, but none ofthese locations offered ideal landing con-ditions.19 (SeeMap III.)

Guam, like the other islands of the Ma-rianas, presented to would-be invaders thecombined hazards of reefs and shore-linecliffs. The northern half of the island wasvirtually inaccessible to amphibious troopsbecause of the reef, th e surf, and the sheercliffs rising from the beaches. Althoughthere were some possible landing points on
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THE MARIANAS 29vehicles.The onlygood harborwas at PortApra, north of Orote Peninsula. The portwas protected by the peninsula proper, byCabras Island on the north, and by abreakwater extending from th e island, andwas considered safe from wind and seafrom almo

Campaign in the Marianas

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