View source for Japanese submarine I-46

{{short description|Type C cruiser submarine}}
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{{Infobox ship career
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|Ship country=[[Empire of Japan]]
|Ship flag=[[Image:Naval Ensign of Japan.svg|60px]]
|Ship name=''Submarine No. 376''
|Ship namesake=
|Ship ordered=
|Ship builder=[[Sasebo Naval Arsenal]], [[Sasebo]], [[Japan]]
|Ship laid down=21 November 1942
|Ship renamed=''I-46'' on 25 May 1943
}}
{{Infobox ship career
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|Ship launched=3 June 1943
|Ship completed= 29 February 1944
|Ship commissioned= 29 February 1944
|Ship fate=Missing October 1944 (see&nbsp;text)
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{{Infobox ship career
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|Ship struck=10 March 1945
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{{Infobox ship characteristics
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|Header caption=
|Ship class=[[Type C submarine#Type-C (I-16 class)|Type C2 submarine]]
|Ship displacement=*{{Convert|2554|LT|t|0|disp=flip}} surfaced
*{{Convert|3564|LT|t|0|disp=flip}} submerged
|Ship length={{convert|109.3|m|ftin|abbr=on}} overall
|Ship beam= {{convert|9.1|m|ftin|abbr=on}}
|Ship draft={{convert|5.35|m|ftin|abbr=on}}
|Ship power=*{{convert|12400|bhp|lk=in|abbr=on}} (diesel)
*{{convert|2000|hp|abbr=on}} ([[electric motor]])
|Ship propulsion=*[[Diesel-electric]]
*1 × [[diesel engine]], 751 tons fuel
*1 × electric motor
|Ship speed=*{{convert|23.5|kn|lk=in}} surfaced
*{{convert|8|kn}} submerged
|Ship range=*{{convert|14000|nmi|abbr=on|lk=in}} at {{convert|16|kn}} surfaced
*{{convert|60|nmi|abbr=on}} at {{convert|3|kn}} submerged
|Ship crew=94
|Ship test depth={{convert|100|m|ft|abbr=on}}
|Ship armament=*8 × bow {{convert|533|mm|in|0|abbr=on}} [[torpedo tubes]]
*1 × [[14 cm/40 11th Year Type naval gun|{{convert|14|cm|in|1|abbr=on}}]] [[deck gun]]
*2 × single or twin [[Type 96 25 mm AT/AA Gun|{{convert|25|mm|in|0|abbr=on}} Type 96]] [[anti-aircraft gun]]s
|Ship notes=
}}
|}

'''''I-46''''' was the first of three [[Type C submarine|Type C]] [[cruiser submarine]]s of the C2 [[ship class|sub-class]] built for the [[Imperial Japanese Navy]]. Commissioned in February 1944, she operated in [[World War II]] during the [[Battle of Leyte]] and [[Battle of Leyte Gulf]] before she was lost in October 1944.

==Design and description==
The Type C submarines were derived from the earlier KD6 sub-class of the {{sclass|Kaidai|submarine|4}} with a heavier torpedo armament for long-range attacks. They [[Displacement (ship)|displaced]] {{Convert|2554|LT|t|0|disp=flip}} surfaced and {{Convert|3561|LT|t|0|disp=flip}} submerged. The submarines were {{convert|109.3|m|ftin|sp=us}} long, had a [[beam (nautical)|beam]] of {{convert|9.1|m|ftin|sp=us}} and a [[draft (hull)|draft]] of {{convert|5.3|m|ftin|sp=us}}. They had a diving depth of {{convert|100|m|ft|sp=us}}.<ref name=b4>Bagnasco, p. 192</ref>

For surface running, the boats were powered by two {{convert|6200|bhp|lk=in|0|adj=on}} [[diesel engine]]s, each driving one [[propeller shaft]]. When submerged each propeller was driven by a {{convert|1000|hp|0|adj=on}} [[electric motor]]. They could reach {{convert|23.6|kn|lk=in}} on the surface and {{convert|8|kn}} underwater.<ref name=c5>Chesneau, p. 201</ref> On the surface, the ''C1''s had a range of {{convert|14000|nmi|lk=in}} at {{convert|16|kn}}; submerged, they had a range of {{convert|60|nmi|abbr=on}} at {{convert|3|kn}}.<ref name=cd3/>

The boats were armed with eight internal bow {{convert|53.3|cm|in|1|abbr=on|sp=us}} [[torpedo tube]]s and carried a total of 20 [[torpedo]]es. They were also armed with a single [[14 cm/40 11th Year Type naval gun|{{convert|140|mm|in|abbr=on}}/40]] [[deck gun]] and two single or twin mounts for [[Type 96 25 mm AT/AA Gun|{{convert|25|mm|in|0|abbr=on}} Type 96]] [[anti-aircraft gun]]s. They were equipped to carry one [[Type A Kō-hyōteki-class submarine|Type A midget submarine]] aft of the [[conning tower]].<ref name=cd3>Carpenter & Dorr, p. 104</ref>

==Construction and commissioning==

Ordered under the [[Rapid Naval Armaments Supplement Programme]] and built by the [[Sasebo Naval Arsenal]] at [[Sasebo]], [[Japan]], ''I-46'' was [[Keel-laying|laid down]] on 21 November 1942 with the name ''Submarine No. 376''<ref name=combinedfleetI46>{{cite web |url= http://www.combinedfleet.com/I-46.htm |title=IJN Submarine I-46: Tabular Record of Movement |first1=Bob |last1=Hackett |first2=Sander |last2=Kingsepp |work=combinedfleet.com |year=2018|access-date=20 August 2020}}</ref> and was numbered ''I-46'' on 25 May 1943.<ref name=combinedfleetI46/> [[Ceremonial ship launching|Launched]] on 3 June 1943 and provisionally attached to the [[Yokosuka Naval District]],<ref name=combinedfleetI46/> she was completed and [[Ship commissioning|commissioned]] on 29 February 1944.<ref name=combinedfleetI46/>

==Service history==

Upon commissioning, ''I-46'' formally was attached to the Yokosuka Naval District and assigned to Submarine Squadron 11 for [[Shakedown cruise|shakedown]] and work-ups.<ref name=combinedfleetI46/> During a training [[sortie]] in the [[Iyo-nada]] on 2 April 1944, she collided underwater with the submarine {{ship|Japanese submarine|Ro-46||2}} off [[Minase Bight]] southwest of [[Kominasa Light]] at 21:45, suffering damage to her [[conning tower]] and [[periscope]]s.<ref name=combinedfleetI46/> After repairs and testing, she arrived at the [[Sasebo Naval Arsenal]] on 7 May 1944 for additional repairs.<ref name=combinedfleetI46/>

''I-46'' was reassigned to Submarine Division 15 in the [[6th Fleet (Imperial Japanese Navy)|6th Fleet]] on 30 May 1944.<ref name=combinedfleetI46/> On 12 August 1944, her commanding officer submitted a memorandum to the [[Headquarters unit|headquarters]] of the 6th Fleet and the commander of Submarine Squadron 11 suggesting improvements to the [[Type 13 (radar)|Type 13]] air search [[radar]] installation and application of the anti-radar coating aboard ''I-46''.<ref name=combinedfleetI46/>

On 13 October 1944, the [[Combined Fleet]] ordered the activation of Operation ''Shō-Gō 1'', the defense of the [[Philippine Islands]], in anticipation of an American invasion of the islands.<ref name=combinedfleetI46/> ''I-46'' departed [[Kure, Hiroshima|Kure]], Japan, to begin her first war patrol and take part in ''Shō-Gō 1'', assigned a patrol area {{convert|120|nmi}} east of [[Leyte]] in the [[Philippines]] as part of the "B" Group.<ref name=combinedfleetI46/> Her patrol area was the westernmost of those assigned to the submarines of her group, and was adjacent to the area assigned to the submarine {{ship|Japanese submarine|I-54|1943|2}}.<ref name=combinedfleetI46/>

On 20 October 1944, the [[Battle of Leyte]] began with U.S. landings on Leyte.<ref name=combinedfleetI46/> In response, major units of the Imperial Japanese Navy converged on Leyte, resulting in the [[Battle of Leyte Gulf]], which lasted from 23 to 26 October 1944.<ref name=combinedfleetI46/> On 24 October, the 6th Fleet ordered eleven submarines, including ''I-46'', to converge in an area extending from [[Samar]] to [[Surigao Strait]].<ref name=combinedfleetI46/>

While ''I-46'' was operating east of Leyte on 25 October 1944, a U.S. [[Maritime patrol aircraft|patrol plane]] forced her to dive at 06:45.<ref name=combinedfleetI46/> A ship she identified from its [[propeller]] noises as a [[destroyer]] pursued her for the next eleven hours, during which she heard over 200 distant [[depth charge]] explosions.<ref name=combinedfleetI46/>

On 26 October 1944, ''I-46'' transmitted a report that she had sighted a small [[Allies of World War II|Allied]] [[convoy]] east of her patrol area.<ref name=combinedfleetI46/> She was never heard from again.<ref name=combinedfleetI46/> When the 6th Fleet ordered her to move to a new patrol station east of Leyte on 27 October 1944, she did not acknowledge the order.<ref name=combinedfleetI46/>

=== Loss ===

The circumstances of ''I-46''′s loss remain unknown.<ref name=combinedfleetI46/> At 12:18 on 28 October 1944, the destroyers {{USS|Gridley|DD-380}} and {{USS|Helm|DD-388}} detected a submarine attempting to penetrate the screen of [[United States Navy]] [[Task Force 38|Task Group 38.4]] — which included the [[aircraft carrier]]s {{USS|Enterprise|CV-6}}, {{USS|Franklin|CV-13}}, {{USS|Belleau Wood|CVL-24}}, and {{USS|San Jacinto|CVL-30}} — east of Leyte.<ref name=combinedfleetI46/> While the aircraft carriers steered away from the submarine contact at high speed, ''Gridley'' made three depth charge attacks against the submarine and ''Helm'' made four.<ref name=combinedfleetI46/> After ''Helm''′s fourth attack, which took place at 14:11, a large explosion followed by two smaller ones occurred.<ref name=combinedfleetI46/> Oil and air bubbles appeared on the surface, and damaged deck planking and human remains were recovered after the attack.<ref name=combinedfleetI46/> The submarine sank at {{coord|10|58|N|127|13|E}}.<ref name=combinedfleetI46/>

On both 30 October and 1 November 1944, {{ship|Japanese submarine|I-26||2}}, ''I-46'', and ''I-54'' all failed to make scheduled daily 19:00 status reports.<ref name=combinedfleetI46/> On 2 December 1944, the Imperial Japanese Navy declared ''I-46'' to be presumed lost east of the Philippines with the loss of all 112 men on board. She was stricken from the Navy list on 10 March 1945.<ref name=combinedfleetI46/>

The identity of the submarine ''Gridley'' and ''Helm'' sank remains a mystery, and has been reported both as ''I-46'' and ''I-54''.<ref name=combinedfleetI46/> In 1976, it also was suggested that the [[destroyer escort]] {{USS|Lawrence C. Taylor|DE-415}} sank ''I-46'' in the [[Philippine Sea]] east of Samar on 18 November 1944, although  the submarine ''Lawrence C. Taylor'' sank probably was {{ship|Japanese submarine|I-41||2}}.<ref name=combinedfleetI46/><ref>{{cite web |url= http://www.combinedfleet.com/I-41.htm |title=IJN Submarine I-41: Tabular Record of Movement |first1=Bob |last1=Hackett |first2=Sander |last2=Kingsepp |work=combinedfleet.com |year=2017|access-date=20 August 2020}}</ref> Some historians have claimed that a submarine the destroyers {{USS|Saufley|DD-465}}, {{USS|Waller|DD-466}}, {{USS|Pringle|DD-477}}, and {{USS|Renshaw|DD-499}} sank in the Ormoc Bay area on 28 November 1944 was ''I-46'', but by then ''I-46'' had been missing for over a month, and they most likely sank {{ship|Japanese submarine|Yu 2||2}}.<ref name=Mühlthaler330>Mühlthaler, p. 330.</ref>

==Notes==
{{Reflist|30em}}

==References==
*{{cite book|last=Bagnasco |first=Erminio |title=Submarines of World War Two |year=1977 |publisher=Naval Institute Press |location=Annapolis, Maryland |isbn=0-87021-962-6}}
*{{cite book|last1=Boyd|first1=Carl|last2=Yoshida|first2=Akikiko|title=The Japanese Submarine Force and World War II|date=2002|publisher=Naval Institute Press|location=Annapolis, Maryland|isbn=1-55750-015-0|name-list-style=amp}}
*{{cite book|last1=Carpenter|first1=Dorr B.|last2=Polmar|first2=Norman|title=Submarines of the Imperial Japanese Navy 1904–1945|year=1986|publisher=Conway Maritime Press|location=London|isbn=0-85177-396-6|name-list-style=amp}}
*{{cite book|title=Conway's All the World's Fighting Ships 1922–1946|editor1-last=Chesneau|editor1-first=Roger|publisher=Conway Maritime Press|location=Greenwich, UK|year=1980|isbn=0-85177-146-7}}
*{{cite web |url=http://www.combinedfleet.com/I-46.htm |title=IJN Submarine I-46: Tabular Record of Movement |last1=Hackett |first1=Bob |first2=Sander |last2=Kingsepp |work=Sensuikan! |publisher=combinedfleet.com |access-date=20 August 2020}}
*{{cite book|last=Hashimoto|first=Mochitsura|others=Colegrave, E.H.M. (translator)|title=Sunk: The Story of the Japanese Submarine Fleet 1942 – 1945|publisher=Cassell and Company|location=London|year=1954|id=ASIN B000QSM3L0}}
* {{cite journal|last1=Mühlthaler|first1=Erich|year=1998 |title=Re:Imperial Japanese Army Transport Submarines|journal=Warship International|volume=XXXV |issue=4 |pages=329–330 |issn=0043-0374}}
*{{cite book|last=Stille|first=Mark|title=Imperial Japanese Navy Submarines 1941-45| series =New Vanguard|volume=135|year=2007|publisher=Osprey Publishing|location=Botley, Oxford, UK|isbn=978-1-84603-090-1}}
{{Type C submarine}}
{{April 1944 shipwrecks}}
{{October 1944 shipwrecks}}

{{DEFAULTSORT:I-046}}
[[Category:1943 ships]]
[[Category:Japanese submarines lost during World War II]]
[[Category:Ships built by Sasebo Naval Arsenal]]
[[Category:Type C2 submarines]]
[[Category:World War II submarines of Japan]]
[[Category:Battle of Leyte Gulf]]
[[Category:Maritime incidents in April 1944]]
[[Category:Maritime incidents in October 1944]]
[[Category:World War II shipwrecks in the Philippine Sea]]
[[Category:World War II shipwrecks in the Pacific Ocean]]
[[Category:Warships lost with all hands]]
[[Category:Submarines lost with all hands]]
[[Category:Submarines sunk by United States warships]]
[[Category:Missing submarines of World War II]]