Patrol Area 14: Us Navy World War Ii Submarine Patrols to the Mariana Islands

By Dave Lotz

As the war in the Pacific progressed, the role of the US submarines evolved to meet the challenges confronting the United States Navy in the Western Pacific. This story is vividly portrayed in Patrol Area 14 and details the exploits of the US submarines in one specific patrol area of the Pacific Ocean, the waters of the Mariana Islands, whose control became essential to victory in the Pacific for the United States and defeat for Japan. Patrol Area 14 describes the submarine patrols from solitary patrols beginning in 1942 to aggressively patrolling the offshore waters, to bold approaches to harbor entrances, to sinking ships within sight of the islands in spite of determined Japanese air and sea anti-submarine efforts and supporting the US invasions of the islands in 1944.

• Language: English
• Publisher: Xlibris US
• Release date: Jan 5, 2018
• ISBN: 9781543446883

Dave Lotz

Dave Lotz is currently the Historian for the War in the Pacific National Historical Park on Guam and American Memorial Park on Saipan and on the Guam Historic Preservation Review Board and the Board for the Guam Preservation Trust. He has previously authored The Best Tracks on Guam, The Guam Guide, and World War II Remnants, Guam and Northern Mariana Islands. Dave has explored Guam, Rota, Aguiguan, Tinian, Saipan, and Pagan while researching the islands World War II history. He has previously held positions as the Guam Parks Administrator and Conservation Resources Chief at Andersen Air Force Base, Guam.

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Copyright © 2018 by Dave Lotz.

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Rev. date: 04/16/2018

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Contents

Preface

Introduction

Chapter 1 - Submarines and the Islands

Misaku Maru and Seahorse

The Mariana Islands

The War

U.S. Navy Submarines

Chapter 2 - First Patrols

Thresher

Three Additional 1942 Patrols to the Islands

Chapter 3 - Into the Second Year of the War

Flying Fish

Five Spring Patrols

Three Sinkings, Two Off Rota

North Sector Patrols

South Sector Patrols

Chapter 4 - Wolf Pack

Snook, Pargo, and Harder

Patrol Area 14 for 1943

Chapter 5 - Carriers

Unyo

23 February 1944

Chapter 6 - Convoys under Attack

Rock, Trout, and Nautilus

Higashi-Matsu Convoys

Higashi-Matsu No. 2, No. 3, and No. 4 Encounter Sand Lance, Pollack, Trigger, and Seahorse

Picuda, Silversides, and Kingfish

Chapter 7 - Sector Patrols of 14

Stingray

The Sectors

Swordfish, Pampanito and Seahorse

Gudgeon

Tambor

Chapter 8 - Greenling

Stealth Reconnaissance

Submarine Photographic Reconnaissance

Greenling in the Southern Mariana Islands

Chapter 9 - Pentathlon Patrols

Sand Lance

Evict to Erase

Gabilan

Silversides

Tunny

Growler

Tilefish and Billfish

Japanese Antisubmarine Efforts

Chapter 10 - Blair’s Blasters

Opening Salvo

Task Group 17.12

Convoys

Japanese Island Defenses

Chapter 11 - June 1944

Lifeguards

FORAGER Support

Battle of the Philippine Sea

Impacts of U.S. Navy Submarine Operations on the War in the Mariana Islands

Chapter 12 - From the Islands

Rescue at Sea

Patrols from Saipan and Guam

From Postwar to the Challenges of the Twenty-First Century

Remnants from the War

Appendix 1 - U.S. Submarines to Patrol Area 14 in World War II

Appendix 2 - Japanese Warships and Merchant Ships Sunk in World War II by U.S. Navy Submarines Assigned to Patrol Area 14, the Mariana Islands

Appendix 3 - Japanese Warships and Merchant Ships Damaged in World War II by U.S. Navy Submarines Assigned to Patrol Area 14, the Mariana Islands

Notes

Bibliography

To

Torpedoman’s Mate Third Class Lawrence Elmer Kidwell, USNR, Tullibee

who died on 31 December 1943

and

Torpedoman’s Mate Third Class Earl Ellis Bowen, USNR, Pollack

who died on 16 March 1944

and all the other U.S. Navy personnel who passed away as operational causalities.

Their contribution to victory in World War II shall always be remembered.

1.WestPacificOcean.tif

Illustration 1. Western Pacific Ocean

Preface

In writing the history of U.S. submarine operations in Patrol Area 14, several items require clarification and consistency. These include the following:

• The spelling of geographical place names and villages in the Mariana Islands and elsewhere using the generally accepted spelling in use during the war. One exception is Tinian, even though this island’s name appears in many documents including the U.S. Navy navigation charts as Tenian.

• The determination of which submarine patrols to include is based upon the operational orders, patrol reports, or orders to change assigned patrol areas during the patrols. Patrol events heading toward Patrol Area 14 or departing from Patrol Areas 14 are occasionally covered to fully describe important patrol events. Therefore Plunger’s attack of May 1943 is covered on the submarine’s journey to assigned Patrol Area 14 in May 1943. Transits only of Patrol Area 14 are ignored such as Stingray’s patrol number four of 26 to 27 June 1942, Tautog’s patrol number eight of 11 to 12 November 1943, Nautilus’s patrol number eight of 9 February 1944, and Searaven’s patrol number eleven of 8 April 1944.

• The rank of the respective submarine commanding officers at the appropriate narrative dates is verified with www.fleetorganization.com.

• In a few cases, my judgment was used on some sinkings although the vast majority relies upon Alden and McDonald, United States and Allied Submarine Successes in the Pacific and Far East During World War II.

• Corrections are made to obvious patrol report errors in aircraft identification. For example, Greenling misidentifying a Mitsubishi G4M Betty for a Mitsubishi Ki-21 Sally and Mitsubishi A6M Zeke for a Nakajima Ki-43 Oscar. Although similar in appearance, the Sally and Oscar were Imperial Japanese Army aircraft, and there was no documentation of Imperial Japanese Army aircraft in the Mariana Islands while there is documentation for Imperial Japanese Navy Bettys and Zekes in the islands.

• The times stated in the book are directly from the patrol reports where the recorded time in the vicinity of Patrol Area 14 was either I (-9) or K (-10) adjacent time zones. This is also indicated in the U.S. Navy’s Time Zone Chart of the World from 1942 and the 1943 chart of Pacific Ocean submarine operating areas. Examples are Gabilan patrol number one on I time and Silversides patrol number ten on K time patrolling nearby and concurrently in May 1944.

• Distances stated of sinkings from nearby islands and other references, based upon patrol reports and Alden and McDonald, are derived from the NOAA Latitude/Longitude calculator at http://www.nhc.noaa.gov/gccalc.shtml.

• The times utilized for the rise and set of the sun and moon, if not taken from patrol reports, is based upon the U.S. Naval Observatory Sun or Moon Rise/Set for One Year at http://aa.usno.navy.mil/data/docs/RS_OneYear.php.

• Miles in Patrol Area 14 are in nautical miles of 6,076 feet as compared to a statue or land mile, which is 5,280 feet. A nautical mile is further defined as one minute of arc of longitude.

• The charts of the Mariana Islands and several of the islands are the nautical charts used during the war with additional geographical place-names included by the author for the benefit of the readers. Meaningful and available submarine patrol report charts are included with supplemental information provided by the author to aid the readers.

• Classes of Imperial Japanese Navy warships are from Jentschura, Jung, and Mickel’s Warships of the Imperial Japanese Navy, 1869-1945, an authority work on the subject. Thus Tunny’s sighting of three Amagiri-class destroyers is stated as Fubuki-class destroyers. Amagiri is a member of the Fubuki-class. Also, Shark’s identification of a Japanese destroyer on 4 June 1944 is stated as the Otori, based upon the Tactical Record of Movement for torpedo boat Otori. In Jentschura, Jung, and Mickel, Otori’s appearance can be taken as a destroyer.

• Sampans is a nebulous term and is just restating what is in the patrol reports. A sampan is not a term associated with watercraft of the islands, but is a term for Far East watercraft propelled by two oars. There is always a possibility that some sampans may have been brought in by the Japanese.

• A standardized format is utilized for numbered Japanese merchant ships of Name Maru No. X.

• U.S. Navy communication intelligence was a major factor, if not the main factor, in locating and sinking enemy ships in the Pacific Ocean during the war. MAGIC is only cited when documentation was located to verify its use although certainly in numerous instances, MAGIC information was utilized by submarine commanders, but not included in patrol reports for security reasons.

• In an analysis of events seventy years ago and while relying on as much documentation as possible, errors of judgment and interpretation are possible for which I accept the responsibility.

• I have been fortunate to become familiar with the islands, ports, and anchorages of the Mariana Islands of Pagan, Saipan, Tinian, Aguijan, Rota, and my home of Guam for over forty years. In 2014, I embarked on a voyage from Japan, stopping at Chichi Jima, Pagan, Saipan, Tinian, and Guam, the major shipping route and destinations of the Japanese to the Mariana Islands in the wartime.

• I am indebted to several for assisting in this endeavor. Certainly my wife Beverly and son Jonathan for archive research assistance and countless readings of the draft book along with Sarah Vinch and Lisa Aguon for proofreading. Certainly assistance from EMC(SS) John Clear, USN Ret., of Submarine Memorabilia; MMCM(SS) John Crouse, USN Ret., Museum Manager, St. Mary’s Submarine Museum, St. Marys, Georgia; MC1 (SW/AW) Jeffrey Jay Price, USN Commander Submarine Squadron 15 Public Affairs; Commander Mike Dodge, USN, Retired; Mark Michael of Rota; Susan Todd Brook, Naval Institute Press; and the staff of the College Park, Maryland National Archives and Records Administration, especially Archives Specialist Nathaniel Patch of Textual Records, Holly Reed and Sharon Culley of Still Picture Records, and Peter Braner of Cartographic Records is sincerely appreciated. Finally to Dwight Naset, USS Pampanito, for a personal tour of the historic World War II submarine in San Francisco, California.

Introduction

As the War in the Pacific progressed, the role of the U.S. submarines evolved to meet the challenges confronting the United States Navy in the Western Pacific. This story is vividly portrayed in Patrol Area 14 that details the exploits of the U.S. submarines in one specific patrol area of the Pacific Ocean, the waters of the Mariana Islands, whose control became essential to victory in the Pacific for the United States and defeat for Japan. Patrol Area 14 describes the submarine patrols from solitary patrols in 1942, to aggressively patrolling the offshore waters, to bold approaches to harbor entrances, and to sink ships within sight of the islands in spite of determined Japanese air and sea antisubmarine efforts. From the war’s beginning, these submarines’ missions progressed as follows:

• Solitary daring patrols deep into enemy waters

• Wolf pack offensive against enemy ships

• Coordinated patrols to support carrier raids

• Exploiting MAGIC intercepts to track and intercept Japanese convoys to the islands

• Operating multiple concurrent sector patrols and rotating patrol sectors

• Intelligence gathering

• Reconnaissance of invasion beaches

• Lifeguarding support for air assaults

• Scouts for the fleet

Patrol Area 14 describes the U.S. Navy submarines’ patrols sent to wrestle control of the vital waters of the Mariana Islands that were transformed from a remote backwater area to a frontline battle zone in the span of a short three years. Once the United States had seized the principal southern islands of the Mariana’s archipelago, the advance bases were utilized for further patrols against Japan by the submarines of the U.S. Navy.

Entwined into this history of U.S. submarine exploits in World War II are the rigors of the lengthy lone patrols, enduring the storms of the Pacific, and survival from deadly enemy depth charge attacks, along with the exhilaration of sinking enemy ships. Interwoven in the submarine narratives are the progress of the war, the events on the islands that impacted the submarines’ missions, and the evolution of patrol tactics to meet the latest challenges of the nautical battlefield.

Patrol Area 14 is just a microglimpse of a larger submarine war in a larger naval war of a world at war. The book provides a unique look at the U.S. submarines in just one section of the ocean in the War in the Pacific.

Illustrations and Tables

Illustration 1. Western Pacific Ocean

Illustration 2. Mariana Islands, U.S. Navy Hydrographic Office Chart No. 5360 of May 1923 with corrections through June 1943. Supplemental information added by author. National Archives and Records Administration.

Illustration 3. Saipan Maru, author’s collection

Illustration 4. Saipan Patrol Team from Mingo, Report of Second War Patrol, of Fumi Maru No. 8 and Kyo Maru No. 10

Illustration 5. U.S. Navy Fleet Submarine Development

Illustration 6. 6. Typical U.S. Submarine. Naval Institute Press

Illustration 7. 5-inch deck gun. Pampanito 2014. Author’s photo.

Illustration 8. Forward torpedo tubes. Pampanito 2014. Author’s photo.

Illustration 9. Periscope shears and SJ and SD radars. Pampanito 2014. Author’s photo.

Illustration 10. Sonar. Pampanito 2014. Author’s photo.

Illustration 11. Bathythermograph, control room. Pampanito 2014. Author’s photo.

Illustration 12. Torpedo Data Computer (TDC) conning tower. Pampanito 2014. Author’s photo.

Illustration 13. Submarine Operation Areas 1943, Navy Department, Office of the Chief of Naval Operations (OP-20-G) Top Secret ULTRA RIP 340, 1943, National Archives and Records Administration.

Illustration 14. Patrol Area 14. Navy Department, Office of the Chief of Naval Operations (OP-20-G) Top Secret ULTRA RIP 340, 1943, National Archives and Records Administration.

Illustration 15. Thresher, 1942. Author’s collection.

Illustration 16. Cuttlefish, 1942, 80-G-K-3350, National Archives and Records Administration

Illustration 17. Otori-class torpedo boat, ONI 41-42.

Illustration 18. Flying Fish. Author’s collection.

Illustration 19. Guam, U.S. Coast and Geodetic Survey National Chart No. 4202 June 1941.

Illustration 20. Apra Harbor, U.S. Coast and Geodetic Survey National Chart No. 4202 June 1941.

Illustration 21. Tokai Maru. Author’s collection.

Illustration 22. Mutuski-class destroyer. Author’s collection.

Illustration 23. Saipan, Tinian, and Aguijan. Supplemental information added by author.

Illustration 24. Shoreline of Laulau Bay, Saipan from Flying Fish, 30 January 1943. 80-G-28880, National Archives and Records Administration.

Illustration 25. Rota, U.S. Navy Hydrographic Office Chart No. 5359 of June 1936. Supplemental information added by author. National Archives and Records Administration.

Illustration 26. Pagan, U.S. Navy Hydrographic Office Chart No. 5358 of May 1923. National Archives and Records Administration.

Illustration 27. Japanese Convoy Routes. Naval Institute Press.

Illustration 28. Whale War Patrol 3 Sheet 1, 8 to 25 March 1943. Notations by author.

Illustration 29. Japanese aircraft carrier Taiyo or Chuyo at Saipan, 7 April 1943, from Haddock. 80-G-65853, National Archives and Records Administration.

Illustration 30. Permit War Patrol 8 Chart, sheet 1. 16 April to 15 May 1943. Notations by author.

Illustration 31. Kinai Maru in 1930. Author’s collection.

Illustration 32. Kinai Maru sinking on 11 May 1943 after being torpedoed by Plunger. Photo taken from Plunger. 80-G-68687, National Archives and Records Administration.

Illustration 33. Whale, War Patrol 4 Chart, sheet 3, 21 May to 9 June 1943. Notations by author.

Illustration 34. Shoan Maru in Tanapag Harbor, Saipan on 11 September 1945. Crippled in torpedo attack by Whale on 27 January 1943. Steamed to Saipan to be sunk in carrier strikes of 23 February 1944. 80-G-K-6615, National Archives and Records Administration.

Illustration 35. Nichiyu Maru, damaged by Halibut on 3 March 1943 and towed to Guam, to be sunk by Destroyer Caperton on 25 June 1944. Author’s collection.

Illustration 36. Tunny. Author’s collection.

Illustration 37. Tunny War Patrol 3 Chart, Sheet 1, 21 June to 5 July 1943. Notations by author.

Illustrations 38 to 41. The series of photographs of Shotoku Maru sunk by Tunny, 28 June 1943, with the southwest coast of the island of Rota in the background. Periscope photographs from Tunny. 80-G-65452, 80-G-65453, 80-G-65454, and 80-G-65455. National Archives and Records Administration.

Illustration 42. Pike, February 1944. 80-G-214327, National Archives and Records Administration.

Illustration 43. Pike. War Patrol 8 Chart, sheet 1, 4 August to 3 September 1943. Notations by author.

Illustration 44. Snapper. Author’s collection.

Illustration 45. Snapper War Patrol 7 Chart, Sheet 1, 13 to 27 August 1943.

Illustration 46. Snapper War Patrol 7 Chart, Sheet 2, torpedo attack on Tokai Maru, 27 August 1943. Notations by author.

Illustration 47. Gudgeon War Patrol 9 Chart, Sheet 1, 12 to 29 September 1943. Notations by author.

Illustration 48. Kamikaze-class destroyer. Author’s collection.

Illustration 49. Taian Maru sunk by Gudgeon on 28 September 1943. ONI 208-J.

Illustration 50. Scorpion War Patrol 3 Chart, 25 October to 24 November 1943. Notations by author.

Illustration 51. Harder. Author’s collection.

Illustration 52. Harder torpedo attack of 12 November 1943 resulting in sinking of Misago Maru No. 11. Harder, Report of Third War Patrol.

Illustration 53. Pargo, May 1945. 80-G-327337, National Archives and Records Administration.

Illustration 54. Pargo War Patrol 2 Chart, Sheet 1, 12 November to 1 December 1943. Notations by author.

Illustration 55. Wakatake-class escort. Author’s collection.

Illustration 56. Harder torpedo attack of 19 November resulting in the sinking of Hokko Maru and Udo Maru. Harder, Report of Third War Patrol.

Illustration 57. Harder torpedo attack of 19 November 1943 resulting in sinking of Nikko Maru. Harder, Report of Third War Patrol.

Illustration 58. Nikko Maru postcard. Author’s collection.

Illustration 59. Haddock War Patrol 8 Chart, Sheet 1, 8 to 11 January 1944 and 19 to 25 January 1944. Notations by author.

Illustration 60. Tullibee, September 1944. 80-G-46134, National Archives and Records Administration.

Illustration 61. Tullibee War Patrol 3 Chart, 14 December 1943 to 10 February 1944. Notations by author.

Illustration 62. Asashio-class destroyer. Author’s collection.

Illustration 63. Tang. Author’s collection.

Illustration 64. Tang War Patrol 1 Chart, Sheet 2, 22 to 25 February 1944. Notations by author.

Illustration 65. Choko Maru postcard. Author’s collection.

Illustration 66. Nautilus. Author’s collection.

Illustration 67. America Maru. Postcard, author’s collection.

Illustration 68. Ch-54 Subchaser. ONI 41-42.

Illustration 69. Seahorse. Author’s collection.

Illustration 70. Kingfish, War Patrol 7 Chart, Sheet 1, 3 March to 1 April 1944. Notations by author.

Illustration 71. Chidori-class torpedo boat. ONI 41-42.

Illustration 72. Stingray War Patrol 10 Chart. Notations by author.

Illustration 73. Patrol Area 14 Sectors, April 1944. National Archives and Records Administration.

Illustration 74. Pampanito, 2014. Author’s photo.

Illustration 75. Aratama Maru. Author’s collection.

Illustration 76. Aratama Maru in Talofofo Bay, 1950s. Author’s collection.

Illustration 77. Kitsugawa Maru. Author’s collection.

Illustration 78. Tambor, April 1945. 80-G-278118, National Archives and Records Administration.

Illustration 79. Greenling. 19_LCM-SS-213-BS-27650, National Archives and Records Administration.

Illustration 80. Sand Lance, May 1945. 80-G-46811, National Archives and Records Administration.

Illustration 81. Patrol Area 14 Pentathlon Patrol, May 1944. National Archives and Records Administration.

Illustration 82. Mitakesan Maru. ONI 208-J.

Illustration 83. Silversides War Patrol 10 Chart, Sheet 1, 7 May to 2 June 1944. Notations by author.

Illustration 84. Mikage Maru No. 18. ONI 208-J.

Illustration 85. Choan Maru, postcard. Author’s collection.

Illustration 86. Tunny War Patrol 6 Chart, Sheet 1, 11 May to 1 June 1944.

Illustration 87. Fubuki-class destroyer. ONI 41-42.

Illustration 88. Bukuyo Maru, postcard. Author’s collection.

Illustration 89. Pintado, February 1944. 80-G-269707, National Archives and Records Administration.

Illustration 90. Pintado War Patrol 1 Chart, 29 May to 8 June 1944.

Illustration 91. Lifeguarding of Stingray off Guam, 12 – 13 June 1944, Stingray War Patrol 11 Chart 1. Notations by author.

Illustration 92. U.S. Navy submarines alongside submarine tender Fulton in Tanapag Harbor, Saipan, 11 November 1944. http://ussarcherfish.com.

Illustration 93. U.S. Navy submarines in Apra Harbor, Guam with submarine tender Sperry. 80-G-474340. National Archives and Records Administration.

Illustration 94. Camp Dealey barracks along the beach at Ipan, Talofofo, Guam. Harry S. Truman Library.

Illustration 95. Camp Dealey swimming beach and dock at Ipan, Talofofo, Guam. Harry S. Truman Library.

Illustration 96. Frank Cable and Oklahoma City, Apra Harbor, Guam. U.S. Navy photo 121115-N-CO162-086.

Front cover:

Top: Seahorse

Bottom: Aratama Maru in Talofofo Bay, Guam, 1945

Background: U.S. Navy Hydrographic Office Chart No. 5360

Chapter 1

Submarines and the Islands

Misaku Maru and Seahorse

In late March 1944, Imperial Japanese Navy Torpedoman Shinji Morimoto, together with the men of the 521st Kokutai, boarded the transport Misaku Maru in the harbor of Yokosuka on the western shore of Tokyo Bay. The 521st Kokutai of the Imperial Japanese Navy, equipped with the sleek modern land-based Yokosuka P1Y Ginga (Francis) twin-engine land-based bombers, had been ordered south to Guam. On the first day of April, Misaku Maru, a forty-five-hundred-ton steamer launched in 1942, departed on the voyage along with twenty-five other Japanese transports jammed with men, equipment, and supplies, escorted by three destroyers, six escort ships, and one minelayer. The convoy, designated Higashi-Matsu No. 4, was destined for Saipan, Guam, Truk, Palau, and Yap. Higashi-Matsu No. 4 was one of numerous convoys headed south in early 1944 as the Japanese urgently reinforced the tropical islands of the western Pacific Ocean, in anticipation of the next American amphibious onslaught in their drive west, during the third year of the War in the Pacific.

For several days, the trip was uneventful as Morimoto, along with the other men of the 521st Kokutai, endured the cramped quarters and meager rations on the seemingly endless journey south. Every day steaming south in the Pacific, their quarters became increasingly hot, humid, and uncomfortable. Fearful of destruction by rumored and later with evidence of the work of enemy submarines, Morimoto’s hopes soared after Misaku Maru survived two submarine attacks on the convoy on the 3rd and 8th of April. By the afternoon of 9 April, eight days since leaving the protection of Tokyo Bay, the convoy was almost within sight of Saipan and the anticipated safety of the island’s Tanapag Harbor. Overhead, four of the magnificent Kawanishi four-engine flying boats flew protective sweeps low ahead of and around the convoy now joined by Mitsubishi twin-engine land bombers for the convoy’s final dash to safety. Since leaving Tokyo Bay, the destroyers and escorts dashing ahead and onto the flanks of the steadily steaming transports were determined to prevent another submarine attack.

Lurking silently, submerged in the path of the approaching convoy, was the submarine Seahorse, having just sunk a Japanese transport east of Guam the previous day, but now patrolling to the northwest of Saipan. Just after the beginning of 9 April at 0026, a lookout on the surfaced submarine sighted a patrolling Japanese aircraft five miles away in the moonlight. Immediately, Lieutenant Commander Slade Cutter, USN, commander of the Seahorse, charted a parallel course to the tracked aircraft, anticipating that the aircraft were providing protective cover to southbound Japanese ships. At 0543, the submarine dove to periscope depth for a long wait for the expected approaching convoy that was unaware of Seahorse’s presence although certain of lurking enemy submarines.

Almost ten hours later, at 1521, Cutter, from the submerged submarine’s periscope, caught a glimpse of a smudge of smoke on the horizon to the northwest that quickly developed into several columns of smoke, masts, and superstructures of transports approaching from over the horizon. Cutter estimated that the large convoy consisted of fifteen to twenty ships escorted by several destroyers and escort ships, along with aerial coverage of menacing seaplanes and bombers, apparently headed for Saipan’s Tanapag Harbor. With quick exposures of the periscope, Cutter navigated Seahorse unnoticed to a firing position. At 1726, he fired a spread of four torpedoes at four overlapping freighters eighteen hundred yards away on the starboard flank of the convoy. While Seahorse was firing torpedoes, the targets suddenly changed course, which resulted in no torpedo hits. Two additional torpedoes were immediately fired at 1729 with one exploding on one of the transport’s amidships. Suddenly, the crew of Seahorse heard an approaching torpedo and quickly descended to evade one of its own torpedoes on a circular run that passed over the submarine several times prior to vanishing. Almost simultaneously, destroyer Ikazuchi and minelayer Sokuten appeared to drop depth charges as Seahorse descended past a thermocline of four degrees at a depth of two hundred feet. Additional depth charges were dropped on the submarine as the boat further descended to 435 feet. From deep below, at 1735, the crew of Seahorse heard the distinctive wrenching sounds of a ship breaking up above accompanied by numerous minor explosions. Five minutes later, the depth charge attacks abruptly ceased as the Japanese warships lost contact with Seahorse beneath the thermocline, thus allowing the submarine to creep away submerged to the northwest out of danger.

Over an hour later at 1849, Cutter carefully brought Seahorse, now heavy forward from seawater taken aboard when the forward torpedoes were fired, struggling slowly up, unable to use the noisy pumps for fear of discovery, to periscope depth. At 1945, he witnessed the target down by the stern with two destroyers close by rendering assistance and taking off survivors. Requiring a battery charge, but wary of the full moon and excellent surface visibility, Seahorse departed to a position fifteen thousand yards away to maintain radar contact on the derelict target ship still accompanied by the two destroyers. Suddenly at 2151, Japanese radar was detected sweeping across the submarine every fifteen seconds, emitting from only fifteen thousand yards away while two destroyers steamed briskly at twenty knots headed to the northeast to slowly vanish. Suddenly at 2151, the flame of an aircraft exhaust was sighted passing overhead, forcing Seahorse to dive. Swiftly, the enemy destroyers reappeared and closed toward the submarine in a high-speed run to within five thousand yards, intent on keeping the submarine down.

During the early morning of 10 April, Seahorse attempted to approach the damaged transport on the surface. Repeated appearances by enemy destroyers and aircraft forced the submarine to dive to avoid being contacted by the enemy. Seahorse finally reached the site of the attack at 0837. Cutter’s periscope observation of the ocean surface revealed a vast amount of floating wreckage consisting of lifeboats, life rafts, part of a deckhouse, boxes, crates, buckets, and cylinders floating in a sea of oil that extended out to the horizon, evidence that the transport had sunk. In the distance, the Japanese destroyers could be heard still pinging, searching with their sonar for Seahorse while Japanese aircraft flew in sight above.

Sunk by Seahorse in the day periscope attack was Misaku Maru, less than forty miles west north of Tanapag Harbor that disappeared beneath the waves at 0100 on 10 April after an attempted tow by transport Toan Maru was abandoned. Only seven naval troops, one soldier, and ten sailors perished with the sinking of Misaku Maru. The remainder of the one thousand naval personnel was rescued by the destroyers. That evening, Seahorse headed west to patrol the shipping lanes farther west of Saipan. Higashi-Matsu No. 4 finally arrived at Saipan later on 10 April, less two transports and the Japanese war material and personnel they were bringing to the islands. From Tanapag Harbor, the ships were split into separate groups to continue their journey to their respective destinations.

Onboard Misaku Maru in the late afternoon of 9 April, Morimoto suddenly felt the ship lurch and shudder beneath him as an explosion ripped into the center of the ship. As flames shot into the air, eighteen men aboard the transport died instantly in the resulting explosion when the torpedo fired from the U.S. Navy submarine Seahorse found its target. Misaku Maru slowly settled by the stern, as two destroyers quickly approached the sinking ship to take on board survivors.

Morimoto struggled aboard one of the destroyers to survive the sinking. A couple of days later, he finally arrived on Guam with fellow members of the 521st Kokutai. They were promptly transported to barracks at the airfield at Tiyan in central Guam without their personal possessions and minus the essential ordnance, vehicles, equipment, and provisions lost on Misaku Maru for maintaining the aircraft.

Morimoto joined a growing multitude of Japanese military personnel on the southern islands of Saipan, Tinian, Rota, and Guam sent to defend these islands of the Japanese Empire in early 1944, but devoid of their equipment and weapons. The men were quickly put to work doing manual labor, along with primarily Korean, Chamorro, and Carolinian workers under cruel slave labor conditions. They labored to construct airfields with adjacent antiaircraft positions, installing artillery positions; fortifying beaches with strong points, trenches, and rifle positions; installing offshore mines and obstacles and everywhere digging tunnels and caves. While the men labored on the islands’ defenses, the women and children of the islands raised the food to support the vastly increased Japanese military population. All labored under the brutal Japanese military government.¹

The sinking of Misaku Maru by Seahorse was one of countless battles of U.S. Navy submarines against Japanese shipping within the 1943 Japanese-designated vital Absolute National Defense Line with the Mariana Islands an essential piece. In the ocean surrounding the islands, the battle that commenced quietly in early 1942 continued until the summer of 1944. For the U.S. submarines, the Mariana Islands’ battleground was designated Patrol Area 14. For the Japanese, the ports of these numerous islands were vital for the convoys transporting the men and weapons to defend the Japanese Empire. For both belligerents, the islands’ locations were crucial in the vast western Pacific Ocean.

The Mariana Islands

The vast, seemingly endless tropical-blue Pacific Ocean is occasionally interrupted by islands that have provided a refreshing interlude for several decades for vessels venturing on apparently continual voyages, under the glaring sun or through the occasional storms, whose winds churn up the waters into treacherous surging waves. In the western Pacific Ocean, numerous tropical islands lie north to south, rising from the deep ocean floor where two broad continental plates collide and where empires met and fought and whose ports offer a refuge from the perils of war at sea. The islands head south toward the equator from the main islands of Japan through the scattering of the Nanpo Shoto, the Izu, Bonin, and Volcano Islands, to the Mariana Islands. The Mariana Islands lie where two great plates of the earth’s crust collide. The Pacific Plate sub ducts under the Philippine Sea Plate, forming the Mariana Trench to the east and south of the Mariana Islands. Here, the ocean is the deepest in the world in the already immense Pacific Ocean. The fifteen Mariana Islands extend in a singular slightly disjointed linear arc with each island frequently within sight of the next island. To the north, varying shades of green mantle the slopes, mingled with the grays and browns of lava, of peaks jutting sharply from the ocean, while toward the south, broad raised green-and-tan plateaus exist above the blues of the water.

The Mariana Islands lie 3,300 nautical miles west of Honolulu, Hawaii, and 1,370 miles east of Manila in the Philippines. The archipelago extends 440 miles north and south, thus placing the northernmost island less than 1,000 miles from Tokyo, Japan. With the southernmost island only 800 miles from the equator, the Mariana Islands are located in the tropical realm of continual warm and humid weather, plentiful rainfall, occasional typhoons, seasonal trade winds, warm ocean waters, coral reefs, and dense jungles.²

From north to south, the Mariana Islands carry their distinct names of Farallon de Pajaros (Uracas), Maug, Asuncion, Agrihan, Pagan, Alamagan, Guguan, Sarigan, Anatahan, Farallon de Medinilla, Saipan, Tinian, Aguijan, Rota, and Guam. The northern nine islands, known as the Gani, are small sharp peaks of volcanoes rising from the deep Pacific Ocean. Next to the south is the small isolated limestone plateau of Farallon de Medinilla. The southern five islands are large and offer vast and varied coastlines, plateaus, plains, mountains, and anchorages for shelter from the ocean voyages and for the exchange of commerce.

Scattered in the ocean among the islands are numerous reefs, shoals, banks, and seamounts, many of which are perilously close to the surface of the ocean. Eleven miles north-northwest of Sarigan lay two rocky pinnacles a half mile apart, Zealandia Bank, with one of the pinnacles rising a few feet above sea level at low tide. Twenty-five miles south-southwest of Guam exists the broad Santa Rosa Reef, a portion only twenty feet below the surface, while closer at twelve miles south-southwest of the island is Galvez Bank, sixty-six feet below the surface. Mariners have been cautioned to avoid these areas as their exact locations were uncertain. Other submerged hazards include Esmeralda Bank twenty miles west of Tinian 180 feet below the surface, Ruby Seamount twenty-one miles northwest of Saipan with a depth of 200 feet, Pathfinder Bank two hundred and fifty miles west of Anatahan with a depth of 30 feet, Supply Reef five miles northwest of Maug with a depth of 26 feet, and Ahyi, a seamount ten miles southeast of Farallon de Pajaros rising to 450 feet of the ocean’s surface. Far to the west, five hundred miles west of Farallon de Pajaros, lies Parece Vela, an isolated coral atoll of three square miles with a few rocks barely above the ocean surface.³

The Mariana Islands are dominated by the tropical maritime climate characterized by high temperatures moderated by the ocean and high humidity. The average temperature on Guam is 80.9 degrees Fahrenheit

2.NavyPubHydroChartNo5360Ed01corrJan1942.tif

Illustration 2. Mariana Islands, U.S. Navy Hydrographic Office Chart No. 5360 of May 1923 with corrections through June 1943. Supplemental information added by author. National Archives and Records Administration.

with slight seasonal changes. Daily highs are generally in the high eighty degrees with lows usually in the mid-seventies. Yearly rainfall averages ninety inches on Guam with the majority falling in the last six months of the year. Both temperature and rainfall diminish slightly as one progresses north in the Mariana’s chain.⁴ Strong northeasterly trade winds dominate early in the year. The late summer months witness monsoon winds from the south while tropical storms and typhoons usually appear later in the year from the east south east. Just prior to World War II, damaging typhoons struck Guam on 3 November 1940 and 3 August 1941.

The currents and tides continually flow and ebb through the islands with their daily and seasonal cycles. Generally, the current flows at a rate of about one knot toward the west, being affected by seasonal or storm winds. Tides, dependent on the cycles of the moon, provide a variance of normally two and a half feet twice a day that results in a stronger current at narrower passages such as at the entrance to Apra Harbor, Guam.⁵

Many of the islands in the Gani, from Farallon de Pajaros to Anatahan, have erupted within recent history: Farallon de Pajaros several times in the 1930s, Asuncion in 1924, Agrihan in 1917, Pagan twice in the 1920s, Alamagan in 1887, and Guguan in 1901.⁶ Six of the nine islands are singular volcanic peaks. Maug is composed of three