 I-401 in 1945 | |
| History | |
|---|---|
 Japan | |
| Name | I-401 |
| Builder | Sasebo Naval Arsenal,Sasebo, Japan |
| Laid down | 26 April 1943 |
| Launched | 11 March 1944 |
| Completed | 8 January 1945 |
| Commissioned | 8 January 1945 |
| Stricken | 15 September 1945 |
| Fate |
|
| General characteristics | |
| Class & type | I-400-classsubmarine |
| Displacement |
|
| Length | 122 m (400 ft) |
| Beam | 12 m (39 ft) |
| Draft | 7 m (23 ft) |
| Propulsion |
|
| Speed |
|
| Range | 37,500 nmi (69,400 km) at 14 kn (16 mph; 26 km/h) |
| Test depth | 100 m (330 ft) |
| Complement | 144 |
| Armament |
|
| Aircraft carried | 3 ×Aichi M6A1 Seiran sea-planes |
I-401 (伊号第四百一潜水艦,I-gō-dai yon-hyaku-ichi-sensuikan) was anImperial Japanese NavySentoku-type (orI-400-class) submarine commissioned in 1945 for service inWorld War II. Capable of carrying three two-seatAichi M6A1 "Seiran" (Mountain Haze)float-equippedtorpedo bombers, theSentoku-class submarines were built to launch a surprise air strike against thePanama Canal. Until 1965, theSentaku-type submarines —I-401 and hersister shipsI-400 andI-402 — were the largest submarines ever commissioned.
TheI-400-class submarines had four 1,680 kW (2,250 hp)diesel engines and carried enough fuel to circumnavigate the world one-and-a-half times. Measuring 122 m (400 ft) long overall, they displaced 5,900 t (6,504 short tons), more than double their typical American contemporaries.[2] Until thecommissioning of theUnited States Navyballistic missile submarineUSS Benjamin Franklin (SSBN-640) in 1965, theI-400-class were the largest submarines ever commissioned.[3]
The cross-section of thepressure hull had a unique figure-of-eight shape which afforded the strength and stability to support the weight of a large, cylindrical, watertight aircrafthangar, 31 meters (102 ft) long and 3.5 meters (11 ft) in diameter, located approximately amidships on the top deck. Theconning tower was offset to port to allow the stowage of threeAichi M6A1Seiran ("Clear Sky Storm")float-equippedtorpedo bombers along the centerline.[2][4] Aircraft were launched from a 37-meter (120 ft)catapult on the forward deck forward of the hangar. A collapsible crane allowed the submarine to retrieve her floatplanes from the water.[5]
In addition to the three floatplanes, eachI-400-class submarine was armed with eight 533-millimeter (21 in)torpedo tubes, all in thebow, with 20Type 95torpedoes,[2][6] a Type 11 140 mm (5.5 in) deck gun aft of the hangar, three waterproofedType 96 triple-mountantiaircraft guns mounted atop the hangar — one forward and two aft of the conning tower — and a single Type 96 25 mm antiaircraft gun mounted just aft of thebridge.[7]
I-400-class submarines had a rather noisy special trim system that allowed them to loiter submerged and stationary while awaiting the return of their aircraft;[2][8]demagnetization cables meant to protect againstmagnetic mines by nullifying the submarine′smagnetic field;[9] an air searchradar, two air/surface-search radar sets, and aradar warning receiver;[10] and ananechoic coating[11] intended to make detection of the submarine while submerged more difficult by absorbing or diffusingsonar pulses and dampening reverberations from the submarine's internal machinery.[11][12][13]
Ordered asSubmarine No. 5232,[14]I-401 waslaid down on 26 April 1943 by theSasebo Naval Arsenal atSasebo,Japan.[3][14] She waslaunched on 11 March 1944,[3][14] and was completed and commissioned on 8 January 1945[3][14] withLieutenant CommanderNobukiyo Nambu in command.[3][14]
Upon commissioning,I-401 was attached to theKure Naval District and assigned to Submarine Division 1 — which also included hersister shipI-400 and the submarinesI-13 andI-14 — in the6th Fleet.[3][14] She also was assigned to SubmarineSquadron 11 for workups.[3] Theflagship of Submarine Division 1, she got underway from Sasebo on the day of her commissioning to begin workups in the westernSeto Inland Sea withI-13 andI-400.[3] She was atKure, Japan, on 19 March 1945 when the United States Navy′sTask Force 58 launched the firstAllied air strike against theKure Naval Arsenal.[3] More than 240 aircraft from theaircraft carriersUSS Essex (CV-9),USS Intrepid (CV-11),USS Hornet (CV-12),USS Wasp (CV-18),USS Hancock (CV-19),USS Bennington (CV-20), andUSS Belleau Wood (CVL-24) attacked Japanese ships in the harbor at Kure.[3] American aircraftstrafedI-401, but she was not damaged.[3]
On 11 April 1945,I-401 put to sea from Kure with the commander of Submarine Division 1,Captain Tatsunosuke Ariizumi, embarked bound forDairen,Manchukuo, where she was to loadfuel oil for transportation back to Japan.[3]I-401 ran aground shortly after leaving port, but freed herself and continued her voyage.[3] On 12 April 1945, however, she detonated a mine laid by aUnited States Army Air ForcesB-29 Superfortress in the Iyo Nada in the Seto Inland Sea 750 meters (820 yd) northeast of theHimeshimalighthouse, bearing 037 degrees from the lighthouse.[3] The explosion damaged some of her instruments and her aftballast tank valves, forcing her to turn back to Kure for repairs.[3] She underwent repairs during May 1945, andshipyard workers installed asnorkel aboard her while she was under repair.[3]
By 1 June 1945, all four submarines of Submarine Division 1 had been fueled and equipped with snorkels. They got underway from Kure that day for a voyage via theShimonoseki Strait, theTsushima Strait, and theSea of Japan toNanao Bay on the western coast ofHonshu nearTakaoka, Japan.[3] After they arrived in Nanao Bay on 4 June 1945, six Aichi M6A1Seiran ("Clear Sky Storm") aircraft of the Kure-based 631st Naval Air Group joined them, flying in after a stop atFukuyama, Japan.[3] On 6 June 1945, the submarines and aircraft began training for night air operations in preparation for a surprise Japanese air strike against thePanama Canal in which the submarines would launch ten M6A1 floatplanes, which were to strike theGatun Locks from the east with six torpedoes and four bombs, emptyingGatun Lake and blocking thecanal to shipping for months.[3] During training, the Japanese demonstrated that four trained men could prepare one of the floatplanes for launch from a submarine in seven minutes and that each submarine could assemble, fuel, arm, and launch all three of the floatplanes it carried in 45 minutes.[3] Despite various obstacles — the presence of mines and U.S. Navy submarines and shortages ofaviation gasoline — the submarines and aircraft launched a number of simulated air strikes.[3]
While Submarine Division 1 was still at Nanao Bay, the expected imminent fall ofOkinawa to U.S. forces and the increasing pace of air strikes by Allied aircraft carriers on theJapanese Home Islands prompted JapaneseImperial General Headquarters to cancel the Panama Canal strike on 12 June 1945 and decide instead to use the submarines and their floatplanes to strike the Allied fleet anchorage atUlithi in theCaroline Islands.[3] The submarines and aircraft completed their flight training on 19 June 1945, with all of the M6A1 floatplanes taking off from the waters of Nanao Bay that day.[3] One failed to return, and the bodies of its two crewmen later washed ashore onSadogashima.[3]
At 13:25 on 25 June 1945, theCombined Fleet issued orders for the attack on Ulithi, dubbedOperation Arashi ("Mountain Storm").[3] The orders called forI-13 andI-14 to transportNakajima C6N1Saiun (Iridiscent Cloud";Allied reporting name "Myrt")reconnaissance aircraft toTruk in the Caroline Islands in late July 1945.[3] InOperation Hikari ("Shining Light"), the C6N aircraft were to conduct a reconnaissance of Ulithi, noting the presence and location of Allied aircraft carriers andtroop transports.[3]I-400 andI-401 then were to launch a combined total of six M6A1 floatplanes — which were to use the reconnaissance information to assist them in targeting Allied ships — on 17 August 1945 for a nighttime strike under a full moon against the Ulithi anchorage, each pilot receiving ahormone injection to improve hisnight vision and each plane armed with an 800-kilogram (1,764 lb) bomb.[3] After the strike, the aircraft were to land near the submarines, andI-13,I-14,I-400, andI-401 all were to proceed toSingapore, where ten new M6A aircraft would await them for embarkation for another strike.[3]
On 13 July 1945,I-401 departed Nanao Bay bound forMaizuru, Japan, which she reached the same day.[3] She began to load ammunition and three months of provisions.[3] After a farewell ceremony for the aircraft crews on 18 July 1945 at the Shiraito Inn at Maizuru attended by the commander-in-chief of the 6th Fleet,Vice AdmiralTadashige Daigo,I-400 andI-401 got underway forŌminato in northern Honshu on 20 July 1945, escorted by aminesweeper.[3]I-401 reached at Ōminato on 21 July 1945[3] andI-400 on 22 July,[15] and after their arrival their crewmen received a day of shore leave, the aircraft had their Japanese markings replaced with American ones, and each submarine brought aboard a model of the Ulithi anchorage as a training aid for the pilots.[3]I-400 departed Ōminato at 14:00 on 23 July 1945, followed byI-401 at 16:00.[3] The two submarines took separate routes in thePacific Ocean far to the east of Japan, planning to rendezvous offPonape in the Caroline Islands on 16 August 1945.[3]
Only a little over four hours into her voyage,I-401 was on the surface inTsugaru Strait at 20:15 on 23 July 1945 when twoImperial Japanese Armycoastal artillerybatteries on the coast ofHokkaido atCape Shiokubi mistook her for an Allied submarine and opened fire on her withType 96 15 cm howitzers.[3] After one of theshells landed only 300 meters (330 yd) off herport quarter,I-401 submerged.[3] After exiting Tsugaru Strait at 06:30 on 24 July 1945, she surfaced, and Ariizumi transmitted a message protesting the coastal artillery bombardment.[3]I-401 weathered atyphoon on 28 and 29 July 1945, and in late July she sighted an unescorted Americantanker, but did not attempt to attack it so as to avoid compromising Operation Arashi.[3] On 31 July 1945,I-401 was offMarcus Island when Ariizumi ordered her to remain on the surface and proceed at 19 knots (35 km/h; 22 mph) to make up for lost time and arrive at the rendezvous withI-400 on schedule.[3]
Concerned by high levels of activity by American aircraft and surface ships near the planned rendezvous point, Ariizumi decided on 14 August 1945 to alter course to the east of theMarshall Islands and meetI-400 at a new location 100 nautical miles (190 km; 120 mi) south of Ponape that evening.[3] He transmitted the new plans in a coded message toI-400, butI-400 never received the message,[3] and whenI-401 surfaced at the rendezvous point 30 minutes after sunset,I-400 was nowhere to be found.[3] According to contingency plans, if the submarines missed their rendezvous, they were to attempt another meeting south of Ulithi at 03:00 on 17 August 1945 and launch their air strike, soI-401 made for that rendezvous point.[3] Meanwhile, Ariizumi consulted with the 6th Fleet and a consensus was reached to postpone the Ulithi raid until 25 August 1945.[3]
On 15 August 1945,EmperorHirohito announced that hostilities between Japan and the Allies would end that day.[3] The senior officers aboardI-401 did not view the announcement as credible and decided to continue with the planned attack on Ulithi,[3] and early on the morning of 16 August 1945I-401 headed for the rendezvous withI-400.[3] When she surfaced after sunset on 18 August 1945, however, she received orders from the 6th Fleet to cancel the attack, and later that day she was ordered to proceed to Kure.[3] Although her crew urged her officers to head for Truk instead and continue fighting, Ariizumi decided that she would proceed to Nanao Bay or Ōminato, after which her crew wouldscuttle her to avoid surrendering her to the Allies, and she headed for Japan.[3]
On 26 August 1945,I-401 received orders to hoist a black flag of surrender and to disarm herself.[3] Accordingly, her crew assembled all three of her M6A1 aircraft and catapulted them unmanned into the sea, dumped their bombs overboard, fired all of her torpedoes, and destroyed all of herlogs,charts,codebooks, and secret documents.[3]
I-401 was in the Pacific Ocean off theSanriku Bight east of Honshu on the night of 28–29 August 1945 when the U.S. Navy submarineUSS Segundo (SS-398) detected her on radar, and at around midnightI-401′s lookouts sightedSegundo, which they identified as a suspicious vessel.[3]I-401 worked up to full speed in an attempt to break contact, but her port diesel engine broke down at dawn on 29 August 1945 andSegundo ordered her to stop.[3] Hernavigation officer went aboardSegundo, whose crew told him thatI-401 must surrender.[3] When Nambu received this information, he contactedTokyo at 05:00 for instructions and received orders to surrender his submarine.[3] Aprize crew fromSegundo made up ofSegundo′sexecutive officer and five enlisted men then boardedI-401, andI-401′s crew presented them with a bottle ofSuntorywhiskey.[3]
AfterI-401′s hatches were chained open to prevent her from submerging without sinking,Segundo′s prize crew ordered her to proceed toYokosuka, Japan, withSegundo′s executive officer in command.[3] Ariizumi insisted thatI-401 instead make for Ōminato and scuttle herself there, but after Nambu disagreed and obeyed the American orders to head for Yokosuka, Ariizumi committed suicide in his cabin, shooting himself with his pistol whileI-401 was in thePhilippine Sea offIzu Ōshima on 30 August 1945.[3]I-401′s crew wrapped his body in a flag and dumped it overboard through a hatch without the Americans noticing.[3] Ariizumi had committedwar crimes while in command of the submarineI-8 duringWorld War II, and suspicions later arose thatI-401′s crew had put Ariizumi ashore nearSendai before she surrendered or that he had swum ashore inTokyo Bay to avoid prosecution, but these theories were not proven.[3]
I-401 andSegundo arrived inSagami Bay on the coast of Honshu at 05:00 on 31 August 1945.[3] The American flag was raised onI-401, and Nambu presented the officer commanding the prize crew with twokatana as a symbol of surrender.[3] Later in the day, a new prize crew from thesubmarine tenderUSS Proteus (AS-19) came aboardI-401 and relieved theSegundo prize crew, after whichI-401 proceeded to Yokosuka[3] and tied up along withI-14 nearProteus and twelve U.S. Navy submarines chosen to represent the U.S. Navy Submarine Force at theJapanese surrender ceremony in Tokyo Bay.[3] At 08:00 on 1 September 1945,I-401′s Imperial Japanese Navybattle flag was lowered, and during the surrender ceremony on 2 September 1945, theCommander, Submarine Force, U.S. Pacific Fleet (COMSUBPAC),Vice AdmiralCharles A. Lockwood, ordered his personal flag hoisted aboardI-401.[3]
The Japanese struckI-401 from the Navy list on 15 September 1945.[3] On 29 September 1945, the commander of U.S. NavyTask Force 38, Vice AdmiralJohn H. Towers, inspected her.[3]
On 29 October 1945,I-401 got underway from Yokosuka southbound for Sasebo with a 40-man American crew aboard in company withI-14,I-400, and thesubmarine rescue vesselUSS Greenlet (ASR-10).[3][15] The ships encountered a heavy storm during their voyage, and the American crews ofI-400 andI-401 noted that theI-400-class submarines′ double-hull construction allowed them to ride remarkably smoothly in the heavy seas.[3] The vessels arrived at Sasebo on 1 November 1945.[3]
After loading Japanesemotorlaunches onto their decks to serve aslifeboats,[15]I-400,I-401, andI-14 departed Sasebo on 11 December 1945[3] under escort byGreenlet[15] bound forPearl Harbor,Hawaii, stopping along the way atApra Harbor onGuam in theMariana Islands from 18 to 21 December 1945, then atEniwetok in the Marshall Islands, and then atKwajalein for food and supplies from 26 to 27 December 1945.[3] They arrived at Pearl Harbor on 6 January 1946 and tied up at the Submarine Base, where a U.S. Navy band and local celebrities welcomed them.[3] On 16 January 1946,I-401 conducted exercises with the submarineUSS Puffer (SS-268) andI-401 andI-14 conducted radar tests with the submarineUSS Steelhead (SS-280).[3]
With postwar relations with theSoviet Union deteriorating rapidly and concerns growing in theUnited States that under postwar agreements the Soviets would demand access to the captured Japanese submarines that would provide theSoviet Navy with valuable information about advanced Japanese submarine designs, the U.S. Navy issued orders on 26 March 1946 to sink all captured Japanese submarines.[3] Accordingly, the U.S. Navy sankI-401 as a target in tests of the Mark 10 Mod 3 exploder off Pearl Harbor on 31 May 1946.[3] She sank by thestern at 10:59 at21°1′N158°07′W / 21.017°N 158.117°W /21.017; -158.117 (I-401) after the submarineUSS Cabezon (SS-334) hit her with twoMark 18 torpedoes.[3]
On 17 March 2005, theHawaii Undersea Research Laboratory's (HURL) deep-diving submersiblesPisces IV andPisces V locatedI-401 offKalaeloa, Hawaii.I-401 lies at a depth of 820 metres (2,690 ft) offBarbers Point.[16] The submersibles foundI-401′s bow broken off just forward of the aircraft hangar and lying not far from the rest of thehull, connected to it by a debris field. The submersibles found the hull sitting upright on the sea floor, and the nameI-401 was clearly visible on the sides of the conning tower.I-401′s Type 96 25 mmanti-aircraft guns appeared to be in almost perfect condition.
