United States Army in World War II: The War in the Pacific

Campaign In the Marianas

by Philip A. Crowl


. . . to Those Who Served



The Author


Part One: Introduction

Chapter 1: Background of Strategy

Prewar Origins of the Central Pacific Concept – War in the Pacific: First Year – Revival of the Central Pacific Concept – General MacArthur’s Strategy – Enter the Army Air Forces – Cairo Conference – Scheduling Operations – Acceleration of Operations – Washington Planning Conferences: February-March 1944

Chapter 2: The Marianas

In History – The Japanese Invasion of Guam – Description of the Islands

Part Two: Saipan

Chapter 3: Planning the Invasion

Organization and Composition of the Attack Force – Tactical Planning – Training and Rehearsals – Loading and Embarkation – The Prospects Ahead: Intelligence of the Enemy

Chapter 4: The Enemy

Prewar Japanese Activities in the Marianas – From Pearl Harbor to Invasion – Japanese Doctrine for Island Defense – Enemy Troop Strength and Dispositions on Saipan – Japanese Expectations

Chapter 5: Invasion

Softening the Target: Pre-D-Day Bombardment – D-Day Bombardment and Ship-to-Shore Movement – Breakdown of the Landing Plan – Expanding the Beachhead – Summary of the Situation at Nightfall

Chapter 6: Capture of Aslito Airfield

Counterattack: Night of 15-16 June – Consolidating the Beachhead: 16 June – Night of 16-17 June – Change of Plans – First Landings of the 27th Infantry Division – D Plus 2: 17 June – D Plus 3: 18 June – The Japanese Situation

Chapter 7: Supporting Arms and Operations

Battle of the Philippine Sea – Logistics – Post-landing Naval Gunfire Support – Close Air Support – Artillery

Chapter 8: The Capture of Nafutan Point

Action of 19 June – Action of 20 June – Action of 21 June – Change of Plan: Relief of the 165th Infantry on Nafutan Point – Action of 22 June – Stalemate on Nafutan: 23-24 June – Nafutan Secured: 25-28 June

Chapter 9: The Fight for Central Saipan – I

Preparations for the Drive to the North – 22 June: The Jump-off – 23 June: Into Death Valley – The First Night in Death Valley – 23 June: Marines on the Flanks – 24 June: Action of the 27th Division – 24 June: Action on the Flanks

Chapter 10: Smith Versus Smith

Relief of Major General Ralph C. Smith – Inter-service Controversy – Conclusions

Chapter 11: The Fight for Central Saipan – II

25 June – The Plight of the Japanese – 26 June – 27 June – Japanese Reactions – 28 June – 29 June – 30 June – Central Saipan: Sum-up

Chapter 12: The Capture of Northern Saipan

Drive to Tanapag – Change of Direction – 5 July – 6 July – 7 July – Final Victory

Part Three: Tinian

Chapter 13: American and Japanese Plans

Plan for the Invasion – The Enemy

Chapter 14: Invasion and Capture

Preliminary Bombardment – The Landings – Japanese Counterattack: 24-25 July – Capture of Northern Tinian – Drive to the South – Tinian Secured

Part Four: Guam

Chapter 15: Plans and Preparations

The Island – Plans for the Invasion – Change of Plans – 77th Infantry Division Training and Preparation – Loading and Embarkation – Preliminary Bombardment – Intelligence of the Enemy

Chapter 16: The Enemy

Troops and Troop Dispositions – Supporting Weapons – Fortifications – Japanese Situation on the Eve of Battle

Chapter 17: The Fight for the Beachhead

W-Day Preliminary Bombardment – From Ship to Shore – The Northern Beaches – The Southern Beaches – Landing the 305th Infantry – Japanese Counterattack – Consolidating the Southern Beachhead: 22-24 July – Landing the Reserves – Consolidating the Northern Beachhead: 22-24 July – Initial Supply Over the Beaches

Chapter 18: The Assault Completed: 25-30 July

Preparations for the Assault on Orote: 25 July – The Fight in the North: 25 July – Japanese Counterattack: 25-26 July – The Capture of Orote – The Capture of Fonte and the Force Beachhead Line – Reconnaissance of Southern Guam

Chapter 19: Pursuit to the North

The Japanese Withdrawal – Drive to the O-2 Line: 31 July-1 August – Supply Problems – To Barrigada and the O-3 Line: 2-4 August – 77th Division: 3 August – 77th Division: 4 August – The Marines: 2-4 August

Chapter 20: Guam Secured

77th Division: 5-6 August – 3rd Marine Division: 5-6 August – Capture of Mount Santa Rosa: 7-8 August – The Marines: 7-8 August – The End on Guam

Part Five: Conclusion

Chapter XXI: Fruits of Victory


Appendix A: Tactical Units of Northern Troops and Landing Force on Saipan

Appendix B: Pacific Ocean Area Unit of Fire for Ground Weapons

Appendix C: Japanese Order of Battle on Saipan

Appendix D: Troop List of the 77th Infantry Division for the Guam Operation

Appendix E: Order of Battle of III Amphibious Corps for the Guam Operation

Bibliographical Note

List of Abbreviations

Glossary of Code Names

Basic Military Map Symbols



I. Saipan Island

II. 27th Division, 16-22 June 1944

III. Advance 5-6 July

IV. Tinian Island

V. Island of Guam

VI. Northern Beachhead, 21-25 July 1944

VII. Southern Beachhead, 21-25 July 1944

Inline Maps

1. Pacific Ocean Areas, 15 June 1944

2. Southern Marianas

3. Japanese Defense Sectors on Saipan

4. D Day on Saipan, 15 June 1944

5. Advance 16-18 June

6. Advance 19-22 June

7. Into Death Valley, 23-24 June 1944

8. 27th Division, 25 June 1944

9. 27th Division, 26-27 June 1944

10. 27th Division, 28-30 June 1944

11. Drive to Tanapag, 1-4 July 1944

12. 105th Infantry, Morning, 6 July 1944

13. 105th Infantry, Afternoon, 6 July 1944

14. Last Days of Battle on Saipan, 7-9 July 1944

15. Japanese Defense Sectors on Tinian

16. Capture of Tinian, 24 July-1 August 1944

17. Disposition of Japanese Troops on Guam, July 1944

18. Landings on Guam, 21 July 1944

19. Capture of Orote Peninsula, 25-29 July 1944

20. Securing the Force Beachhead Line, 26-29 July 1944

21. Reconnaissance of Southern Guam, 28 July-2 August 1944

22. Drive to O-2 Line, 31 July-1 August 1944

23. Approach to Barrigada, 2 August 1944

24. Advance to O-3 Line, 2-4 August 1944

25. Advance to O-4 Line, 5-6 August 1944

26. Advance 7-8 August and Capture of Mt. Santa Rosa


1. Estimated Strength of the Japanese Garrison on Tinian

2. Artillery on Guam


1. Task Organization for Major Commands for Attack on Saipan and Tinian

2. Task Organization for Major Commands for Attack on Guam


Top Naval Commanders in the Marianas Campaign – Vice Adm. Richmond Kelly Turner – Lt. Gen. Holland M. Smith – Maj. Gen. Ralph C. Smith – Destruction at Charan Kanoa – Dummy Searchlight Platform on East Coast of Saipan – Japanese Type 96 25-mm. Machine Cannon – Amphibian Tractors in Line Abreast Formation – Congestion on 2nd Marine Division Beach – Early Wave on the Beach – Marines Digging Foxholes – D-Day Command Post – Narrow-Gauge Railroad Near Charan Kanoa – Soldiers Watch Destruction of a Pillbox – Reinforcements Moving Inland – 105th Infantrymen Wading in From the Reef – Aslito Field Becomes Conroy Field – Examining an Enemy Gun – Shore Parties Unloading Supplies on BLUE Beach 1 – Caterpillar Tractor Pulling Ammunition Pallets From an LCM – Pontoon Causeway and Barge in Charan Kanoa Harbor – North Central Saipan – Seaward Cliff Line, Nafutan Peninsula – 27th Division Troops at Cliff Edge, Nafutan Peninsula – Infantryman at the Base of Cliff, Nafutan Peninsula – Infantryman Milking an Island Goat – Skirmish Line – Americans Rescuing Baby From Nafutan Cave – Hill 500 – Marines on the Crest of Hill 500 – Japanese Type 93 13.2-mm. Machine Gun – Japanese Field of Fire – Mt. Tapotchau Dominating Death Valley – Tree Line in Death Valley – Driven to Concealment – Marines Emerging From Purple Heart Ridge Complex – Tank-Infantry Cooperation – In Hell’s Pocket Area – Inland of Garapan Harbor – Maj. Gen. Sanderford Jarman – Lt. Gen. Holland M. Smith – Lt. Gen. Robert C. Richardson, Jr. – Maj. Gen. Ralph C. Smith – Lower End of Death Valley – Bazooka Team Preparing to Fire – Maj. Gen. George W. Griner – Truck-Mounted Rocket Launchers Firing – Marines Dash Through Blazing Garapan – Infantrymen Observe Hill 767 – Troops Searching Out the Enemy – Harakiri Gulch – Waiting To Move Up – Marines Examining Destroyed Enemy Tank – Flame Thrower Blasting Paradise Valley Cave – Coastal Area, Northwest Tinian – Marianas Leaders Confer at Tinian – LVT With Ramp – 155-mm. Gun Firing at Tinian From Saipan – Invasion Craft – 4th Marines Wading Toward WHITE Beach 1 – Ushi Point Airfield – Open Terrain of Central Tinian – 155-mm. Howitzer Emplacement on Tinian – Cliff Line at Tip of Orote Peninsula – Orote Peninsula – Maj. Gen. Roy S. Geiger – Japanese Beach Obstacles at Guam – Japanese Open-Trench Beach Defenses at Agat – First Wave of Landing Craft Heads for Agat Beaches – Asan’s GREEN and BLUE Beaches – 3rd Marine Division Beachhead – Circling Landing Craft – 4th Marines Moves Inland Toward Mt. Alifan – Assembly Area of 305th Infantry on 22 July – Smoldering Japanese Tanks – Maj. Gen. Andrew D. Bruce – Pontoon Barge With Crane – Troops in Bivouac – Japanese Airfield, the Prime Objective on Orote Peninsula – Marine Corps Officers – Antitank Crew – Men of Company B, 305th RCT – Forward Observers of the 77th Division – Artillery Column Moving Inland – Mt. Santa Rosa – Burning U.S. Medium Tanks – Lt. Gen. Alexander A. Vandegrift – LSTs, LCIs, Small Boats – Harmon Field, Guam

Photographs are from Department of Defense files with the following exceptions: photographs on pages 37 and 38 from the personal files of Col. Robert C. Richardson, III; the photograph on page 418 from the Bishop Museum, Oahu, Hawaii; and that on page 444, by J. R. Eyerman – Life. (c) 1950 Time Inc.

United States Army in World War II

Stetson Conn, General Editor

Advisory Committee, (As of 15 March 1959)

Elmer Ellis, University of Missouri

Maj. Gen. Hugh M. Harris, U.S. Continental Army Command

Samuel Flagg Bemis, Yale University

Brig. Gen. Edgar C. Doleman, Army War College

Gordon A. Craig, Princeton University

Brig. Gen. Frederick R. Zierath, Command and General Staff College

Oron J. Hale, University of Virginia

Brig. Gen. Kenneth F. Zitzman, Industrial College of the Armed Forces

W. Stull Holt, University of Washington

Col. Vincent J. Esposito, United States Military Academy

T. Harry Williams, Louisiana State University

Office of the Chief of Military History

Col. Warren H. Hoover, Acting Chief

Stetson Conn, Chief Historian

Lt. Col. Joseph Rockis, Chief, Histories Division

Lt. Col. E. E. Steck, Chief, Publication Division

Joseph R. Friedman, Editor in Chief

Elliot Dunay, Chief, Cartographic Branch

Margaret E. Tackley, Chief, Photographic Branch