View source for Japanese submarine I-6

{{Short description|Imperial Japanese Navy J2 type submarine}}
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{{Infobox ship image
|Ship image=File:Japanese submarine I-6 in 1935.jpg
|Ship caption=''I-6'' in 1935 or 1936.
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{{Infobox ship career
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|Ship country=[[Imperial Japanese Navy]]
|Ship flag=[[Image:Naval Ensign of Japan.svg|45px|RN Ensign]]
|Ship name=''I-6''
|Ship namesake=
|Ship ordered=
|Ship builder=[[Kawasaki Shipbuilding Corporation]], [[Kobe]], [[Japan]]
|Ship laid down=14 October 1932
|Ship launched=31 March 1934
|Ship completed=15 May 1935
|Ship acquired=
|Ship commissioned=15 May 1935
|Ship decommissioned=15 December 1938
}}
{{Infobox ship career
|Hide header=yes
|Ship recommissioned=by 1 April 1939
|Ship decommissioned=
|Ship in service=
|Ship out of service=
|Ship struck=
|Ship reinstated=
|Ship honors=
|Ship fate=Sunk 16 June 1944 (see&nbsp;text)
}}
{{Infobox ship career
|Hide header=yes
|Ship struck=10 September 1944
|Ship notes=
}}
{{Infobox ship characteristics
|Hide header=
|Header caption=
|Ship class=[[Junsen type submarine|J2 type]] [[submarine]]
|Ship displacement=*1,900 tons (surfaced)
*3,061 tons(submerged)
|Ship length={{convert|98.50|m|ftin|abbr=on}}
|Ship beam={{convert|9.06|m|ftin|abbr=on}}
|Ship draft={{convert|5.31|m|ftin|abbr=on}}
|Ship depth={{convert|7.58|m|ftin|abbr=on}}
|Ship propulsion=*2 × [[Imperial Japanese Navy Technical Department|Kampon]] Mk.1A Model 7 [[diesel engine]]s, 8,000 [[Brake horsepower|bhp]] (6,766 [[Kilowatt|kW]]), 2&nbsp;shafts
*Two electric motors, 2600 [[Shaft horsepower|shp]] (2,199&nbsp;kW)
|Ship speed=*{{convert|20|kn|abbr=on}} (surfaced)
*{{convert|7.5|kn|abbr=on}} (submerged)
|Ship range=*{{convert|20,000|nmi|abbr=on}} at {{convert|10|kn|abbr=on}} (surfaced)
*{{convert|65|nmi|abbr=on}} at {{convert|3|kn|abbr=on}} (submerged)
|Ship test depth={{convert|80|m|ft|0|abbr=on}}
|Ship complement=80 officers and men
|Ship sensors=
|Ship EW=
|Ship armament=*6 × {{convert|533|mm|in|adj=on|abbr=on|0}} [[torpedo tube]]s (4&nbsp;forward, 2&nbsp;aft)
*17 × [[Japanese_53_cm_torpedo#Type_89|Type 89 torpedo]]es
*1 x {{convert|127|mm|in|abbr=on|adj=on|0}} gun
*1 x {{convert|13.2|mm|in|adj=on|abbr=on|1}} [[machine gun]]
|Ship armour=
|Ship armor=
|Ship boats=1 x ''[[Daihatsu]]'' (added August&nbsp;1942–February&nbsp;1943)
|Ship aircraft=1 x [[Yokosuka E6Y]]1 (until mid-1940)
|Ship aircraft facilities=[[Hangar]], [[Aircraft catapult|catapult]] (both removed mid-1940)
|Ship notes=
}}
|}
'''''I-6''''' was an [[Imperial Japanese Navy]] [[Junsen type submarine|J2 type]]  [[submarine]] commissioned in 1935. She was a large [[cruiser submarine]] that served in the [[Second Sino-Japanese War]] and [[World War II]]. During the latter conflict she operated in support of the [[attack on Pearl Harbor]], torpedoed the [[aircraft carrier]] {{USS|Saratoga|CV-3}}, conducted anti-shipping patrols in the [[Indian Ocean]] and [[South Pacific Ocean]], and took part in the [[Aleutian Islands campaign]] and [[New Guinea campaign]] before she was sunk in June 1944.

==Design==
''I-6'' was the only ''Junsen II''- (or "J2"-) type submarine. After the four [[Type J1 submarine|''Junsen I''-type]] submarines ({{ship|Japanese submarine|I-1||2}}, {{ship|Japanese submarine|I-2||2}}, {{ship|Japanese submarine|I-3||2}}, and {{ship|Japanese submarine|I-4||2}}), the Japanese had built {{ship|Japanese submarine|I-5||2}} as a modified ''Junsen I'', introducing an aviation capability to the ''Junsen'' type with the inclusion of a [[hangar]] that allowed ''I-5'' to carry and operate a [[floatplane]]. ''I-6'' represented the next step in the evolution of this aviation capability, as she had both a hangar and a [[Aircraft catapult|catapult]] for a floatplane. The next and last ''Junsen''-type submarines, {{ship|Japanese submarine|I-7||2}} and {{ship|Japanese submarine|I-8||2}}, the only ''Junsen III''-type submarines, also each had a hangar and catapult for a floatplane.

==Construction and commissioning==
Built by [[Kawasaki Shipbuilding Corporation|Kawasaki]] at [[Kobe]], [[Japan]], ''I-6'' was [[Keel-laying|laid down]] on 14 October 1932.<ref name=ijnsubsiteI6>[http://www.ijnsubsite.info/I-Sub%20Details/I-6.htm I-6 ijnsubsite.com 18 September 2018 Accessed 29 January 2022]</ref><ref name=combinedfleetI6>{{cite web |url= http://www.combinedfleet.com/I-6.htm |title=IJN Submarine I-6: Tabular Record of Movement |first1=Bob |last1=Hackett |first2=Sander |last2=Kingsepp |work=combinedfleet.com |date=6 October 2012|access-date=12 August 2020}}</ref> She was [[Ceremonial ship launching|launched]] on 31 March 1934<ref name=ijnsubsiteI6/><ref name=combinedfleetI6/> and completed and [[Ship commissioning|commissioned]] on 15 May 1935.<ref name=ijnsubsiteI6/><ref name=combinedfleetI6/>

==Service history==
===1935–1937===
Upon commissioning, ''I-6'' was attached to the [[Yokosuka Naval District]].<ref name=ijnsubsiteI6/><ref name=combinedfleetI6/> On 1 June 1935, she was assigned to Submarine [[Division (naval)|Division]] 8 in Submarine [[Squadron (naval)|Squadron]] 1 in the [[1st Fleet (Imperial Japanese Navy)|1st Fleet]], a component of the [[Combined Fleet]].<ref name=ijnsubsiteI6/> She was taking part in maneuvers off [[Ise Bay]] at 14:27 on 1 August 1935 when she collided with the [[destroyer]] {{ship|Japanese destroyer|Akatsuki|1932|2}}.<ref name=combinedfleetI6/> She suffered damage to her [[periscope]]s and proceeded to [[Yokosuka]], Japan, for repairs.<ref name=combinedfleetI6/> She was reassigned directly to the Yokosuka Naval District on 15 November 1935.<ref name=ijnsubsiteI6/> In July 1936, she embarked a [[Watanabe E9W]]1 ([[World War II Allied names for Japanese aircraft|Allied reporting name]] "Slim") [[reconnaissance seaplane]] for testing purposes.<ref name=combinedfleetI6/>

On 1 December 1936, ''I-6'' returned to duty in Submarine Division 8 in Submarine Squadron 1 in the 1st Fleet.<ref name=ijnsubsiteI6/> On 27 March 1937, she departed [[Sasebo]], Japan, in company with ''I-1'', ''I-2'', ''I-3'', ''I-4'', and ''I-5'' for training in the vicinity of [[Qingdao]], [[China]].<ref name=ijnsubsiteI6/><ref name=ijnsubsiteI1>[http://www.ijnsubsite.info/I-Sub%20Details/I-1.htm I-1 ijnsubsite.com 1 July 2020 Accessed 27 January 2022]</ref><ref name=ijnsubsiteI2>[http://www.ijnsubsite.info/I-Sub%20Details/I-2.htm I-2 ijnsubsite.com 15 April 2018 Accessed 28 January 2022]</ref><ref name=ijnsubsiteI3>[http://www.ijnsubsite.info/I-Sub%20Details/I-3.htm I-3 ijnsubsite.com 3 May 2018 Accessed 29 January 2022]</ref><ref name=ijnsubsiteI4>[http://www.ijnsubsite.info/I-Sub%20Details/I-4.htm I-4 ijnsubsite.com 18 May 2018 Accessed 29 January 2022]</ref><ref name=ijnsubsiteI5>[http://www.ijnsubsite.info/I-Sub%20Details/I-5.htm I-5 ijnsubsite.com 18 May 2018 Accessed 27 January 2022]</ref> The six submarines concluded the training cruise with their arrival at [[Ariake Bay]] on 6 April 1937.<ref name=ijnsubsiteI6/><ref name=ijnsubsiteI1/><ref name=ijnsubsiteI2/><ref name=ijnsubsiteI3/><ref name=ijnsubsiteI4/><ref name=ijnsubsiteI5/>

===Second Sino-Japanese War===
On 7 July 1937 the first day of the [[Marco Polo Bridge Incident]] took place, beginning the [[Second Sino-Japanese War]].<ref name=combinedfleetI6/> In September 1937 Submarine Squadron 1 was reassigned to the [[3rd Fleet (Imperial Japanese Navy)|3rd Fleet]],<ref name=boydyoshidap54>Boyd and Yoshida, p. 54.</ref> which in turn was subordinated to the [[China Area Fleet]] for service in Chinese waters.<ref name=boydyoshidap54/> The squadron, consisting of ''I-1'', ''I-2'', ''I-3'', ''I-4'', ''I-5'' and ''I-6'',<ref name=boydyoshidap54/> deployed to a base at [[Hong Kong]] with the [[submarine tender]]s {{ship|Japanese submarine tender|Chōgei||2}} and {{ship|Japanese submarine tender|Taigei||2}} in September 1937.<ref name=boydyoshidap54/> From Hong Kong, the submarines began operations in support of a Japanese [[blockade]] of China and patrols of China's central and southern coast.<ref name=boydyoshidap54/> From 20<ref name=ijnsubsiteI6/> or 21<ref name=combinedfleetI6/> (sources disagree) to 23 August 1937, all six submarines of Submarine Squadron 1 operated in the [[East China Sea]] as distant cover for an operation in which the battleships {{ship|Japanese battleship|Nagato||2}}, {{ship|Japanese battleship|Mutsu||2}}, {{ship|Japanese battleship|Haruna||2}}, and {{ship|Japanese battleship|Kirishima||2}} and the [[light cruiser]] {{ship|Japanese cruiser|Isuzu||2}} ferried troops from [[Tadotsu, Kagawa|Tadotsu]], Japan, to [[Shanghai]], China.<ref name=combinedfleetI6/>

Submarine Squadron 1 was based at Hong Kong until the autumn of 1938.<ref name=boydyoshidap54/> In an effort to reduce international tensions over the conflict in China, Japan withdrew its submarines from Chinese waters in December 1938.<ref name=boydyoshidap54/>

===1938–1941===

Remaining a unit of Submarine Division 8, ''I-6'' was placed in Second Reserve in the Yokosuka Naval District on 15 December 1938,<ref name=ijnsubsiteI6/> then on 1 April 1939 began an assignment at the [[Torpedo]] School in the Yokosuka Naval District at Yokosuka.<ref name=ijnsubsiteI6/> In mid-1940, her hangar and catapult were removed,<ref name=combinedfleetI6/> and thereafter she did not operate aircraft. Submarine Squadron 2, including ''I-6'', was resubordinated to the [[6th Fleet (Imperial Japanese Navy)|6th Fleet]] on 15 November 1940.<ref name=ijnsubsiteI6/><ref name=combinedfleetI6/>

On 10 November 1941 — by which time ''I-4'', ''I-5'', ''I-6'', and the submarine {{ship|Japanese submarine|I-7||2}} made up Submarine Division 8, with ''I-7'' serving as squadron flagship<ref name=combinedfleetI6/> — the [[commander-in-chief]] of the 6th Fleet, [[Vice Admiral]] [[Mitsumi Shimizu]], gathered the [[commanding officer]]s of the fleet's submarines together for a meeting aboard his [[flagship]], the light cruiser {{ship|Japanese cruiser|Katori||2}}, which was anchored in [[Saeki Bay]].<ref name=combinedfleetI6/> His chief of staff briefed them on the upcoming [[attack on Pearl Harbor]], which would bring Japan and the [[United States]] into [[World War II]].<ref name=combinedfleetI6/> As the Imperial Japanese Navy began to deploy for the upcoming [[Pacific War|conflict in the Pacific]], ''I-4'', ''I-5'', ''I-6'', and ''I-7'' got underway from Yokosuka at 13:00 on 16 November 1941, bound for the [[Hawaiian Islands]].<ref name=combinedfleetI6/> The submarines received the message "Climb [[Yu Shan|Mount Niitaka]] 1208" ({{langx|ja|Niitakayama nobore 1208}}) from the [[Combined Fleet]] on 2 December 1941, indicating that war with the [[Allies of World War II|Allies]] would commence on 8 December 1941 [[Japan Standard Time|Japan time]], which was on 7 December 1941 on the other side of the [[International Date Line]] in [[Hawaii]].<ref name=combinedfleetI6/>

===World War II===
====First war patrol====
On 7 December 1941, the submarines of Submarine Squadron 2 took up patrol stations across a stretch of the [[Pacific Ocean]] from northeast to northwest of [[Oahu]].<ref name=combinedfleetI6/> The submarines had orders to conduct reconnaissance in the area and attack any ships which [[sortie]]d from [[Pearl Harbor]] during or after the attack, which occurred that morning.<ref name=combinedfleetI6/> ''I-6''′s patrol area was between those of ''I-4'' and ''I-5'' and was located off the northern entrance of [[Kaiwi Channel]] between [[Molokai]] and Oahu.<ref name=combinedfleetI6/> At 08:40 on 9 December 1941, ''I-6'' sighted the [[United States Navy]] [[aircraft carrier]] {{USS|Enterprise|CV-6}} — which she misidentified as a {{sclass|Lexington|aircraft carrier|2}} — and two [[heavy cruiser]]s north of Molokai steaming northeast at {{convert|20|kn|0}}.<ref name=combinedfleetI6/> She attempted to attack ''Enterprise'', but was forced to go deep before she could.<ref name=combinedfleetI6/> Several hours later she managed to transmit a sighting report, which resulted in the Japanese ordering nine submarines to attempt to intercept ''Enterprise'', which they assumed was bound for the [[United States West Coast]].<ref name=combinedfleetI6/> Out of position to participate in the pursuit of ''Enterprise'', ''I-6'' was ordered to take up a new patrol area south of Oahu in waters between the [[Kauai Channel]] and an area southeast of Pearl Harbor.<ref name=combinedfleetI6/> Later in December, one of her torpedomen was injured during a routine [[torpedo]] inspection; he died several days later of [[sepsis]] on 27 December 1941 and was [[Burial at sea|buried at sea]].<ref name=combinedfleetI6/>

On 9 January 1942, the submarine {{ship|Japanese submarine|I-18||2}} reported sighting a ''Lexington''-class aircraft carrier {{convert|270|nmi}} northeast of [[Johnston Island]], and the 6th Fleet ordered a number of submarines including ''I-1'' to form a picket line northeast of Johnston Island to find the carrier.<ref name=combinedfleetI6/> When ''I-1'' developed engine trouble, ''I-6'' received orders to replace her in the picket line.<ref name=combinedfleetI6/> During the daylight hours of 10 January 1942, {{nowrap|''I-6''′s}} lookouts sighted planes from the carrier on five separate occasions, and her [[navigator]] plotted their courses and used the information to estimate the carrier's position.<ref name=combinedfleetI6/> While on the surface {{convert|270|nmi}} northeast of Johnston Island at 18:41 on 11 January 1942, she sighted a U.S. Navy destroyer and submerged.<ref name=combinedfleetI6/> Not long afterwards, the aircraft {{USS|Saratoga|CV-3}} hove into view at {{coord|19|N|165|W}}, steaming southeast at {{convert|15|kn|0}} and accompanied by a heavy cruiser and another destroyer.<ref name=combinedfleetI6/> ''I-6'' fired three [[Japanese_53_cm_torpedo#Type_89|Type 89 torpedo]]es at ''Saratoga'' at a range of {{convert|4,700|yd|m|sigfig=2}}, and at 19:15 one of them hit ''Saratoga'' amidships on her [[Port and starboard|port]] side, killing six [[Fireman (steam engine)|firemen]] and flooding three [[boiler room (ship)|boiler room]]s.<ref name=combinedfleetI6/> Taking on 1,100 tons of water, ''Saratoga'' heeled to [[Port and starboard|starboard]] and then to port and lost headway.<ref name=combinedfleetI6/> ''I-6'' went to a depth of {{convert|330|ft|m}}, and when the escorting destroyers began a counterattack at 19:58, they could not locate her.<ref name=combinedfleetI6/> Her sound operator reported hearing two large explosions followed by a number of smaller ones which suggested that ''Saratoga'' had sunk and was breaking up on her way to the bottom, and after 22:00 ''I-6'' transmitted a report claiming two hits on, and the probable sinking of, a ''Lexington''-class aircraft carrier.<ref name=combinedfleetI6/> In fact, ''Saratoga'' survived, but the damage ''I-6'' inflicted kept her out of combat for the next six months.<ref name=combinedfleetI6/>

On 12 January 1942, ''I-6'' departed her patrol area bound for [[Kwajalein]], which she reached on 22 January 1942 with only {{convert|800|L|impgal usgal|sp=us}} of fuel left.<ref name=combinedfleetI6/> She got back underway on 24 January 1942 bound for Yokosuka, which she reached on 2 February 1942.<ref name=combinedfleetI6/> She was [[drydock]]ed in early February 1942 and began a refit and overhaul.<ref name=combinedfleetI6/>

====Second war patrol====
While ''I-6'' was at Yokosuka, Submarine Squadron 2 — consisting of ''I-1'', ''I-2'', ''I-3'', ''I-4'', ''I-6'', and the squadron flagship, ''I-7'' — was assigned to the [[Dutch East Indies campaign|Dutch East Indies Invasion]] Force in the Southeast Area Force on 8 February 1942.<ref name=combinedfleetI6/> On 13 February, the staff of Submarine Division 8 transferred from ''I-6'' to ''I-4'', and ''I-6'' departed Yokosuka on 14 February 1942 bound for the [[Netherlands East Indies]].<ref name=combinedfleetI6/> She arrived at [[Staring Bay]] on the [[Southeast Peninsula, Sulawesi|Southeast Peninsula]] of [[Celebes]] just southeast of [[Kendari]] on 22 February 1942.<ref name=combinedfleetI6/> At 07:00 on 23 February 1942, she got back underway in company with ''I-4'' and ''I-5'' to begin her second war patrol, bound for a patrol area in the [[Indian Ocean]] west of [[Sumatra]].<ref name=combinedfleetI6/> While ''I-5'' and ''I-6'' were on the surface west of [[Timor]] en route their patrol areas on 25 February 1942, an Imperial Japanese Navy [[Mitsubishi Ki-15|Mitsubishi C5M]] (Allied reporting name "Babs") [[reconnaissance aircraft]] escorted by nine [[Mitsubishi A6M Zero]] (Allied reporting name "Zeke") [[Fighter aircraft|fighters]] sighted the vessels at 12:30 [[Japan Standard Time]] and misidentified them as [[Royal Netherlands Navy]] submarines.<ref name=combinedfleetI6/> The Zeroes made repeated [[strafing]] attacks that forced ''I-6'' to submerge, but she suffered no damage.<ref name=combinedfleetI6/> Her patrol otherwise was uneventful, and she concluded it with her arrival at [[Penang Island|Penang]] in Japanese-occupied [[British Malaya]] on 8 March 1942.<ref name=combinedfleetI6/>

====Third war patrol====
Orders arrived from the [[Headquarters unit|headquarters]] of the [[Combined Fleet]] for all the submarines of Submarine Squadron 2 except for ''I-1'' to conduct reconnaissance operations along the coast of [[Ceylon]] and western coast of [[India]] in preparation for Operation C, the upcoming [[Indian Ocean raid]] by the aircraft carriers of the Combined Fleet's [[Kido Butai|Mobile Force]].<ref name=combinedfleetI6/> Accordingly, ''I-6'' departed Penang on 26 March 1942 to begin her third war patrol, assigned a patrol area in the Indian Ocean west of [[Bombay]], India, and north of the [[Maldive Islands]].<ref name=combinedfleetI6/> On 27 March, the [[Kriegsmarine|German naval staff]] in [[Berlin]] asked that Japan begin anti-shipping operations against [[Allies of World War II|Allied]] [[convoy]]s in the Indian Ocean.<ref name=combinedfleetI6/>

At 16:35 on 31 March 1942, ''I-6'' was in the Indian Ocean off [[Maliku Kandu|Eight Degree Channel]] when she sighted an Allied [[Steamship|steamer]].<ref name=combinedfleetI6/> She commenced an approach and was about to fire torpedoes when she identified the ship as a [[hospital ship]] — probably the [[United Kingdom|British]] hospital ship {{HMHS|Vita}} on a voyage from [[Addu Atoll]] to the Ceylon area — and called off the attack.<ref name=combinedfleetI6/> On the afternoon of 2 April 1942, ''I-6'' was in the [[Arabian Sea]] {{convert|300|nmi}} southwest of Bombay when she sighted the British 5,897-ton steamer {{SS|Clan Ross||2}}, which was on her way from [[Liverpool]], [[England]], to [[Cochin]], India, carrying 3,655 tons of general cargo and 1,027 tons of explosives.<ref name=ijnsubsiteI6/><ref name=combinedfleetI6/> She fired two torpedoes at a range of {{convert|1,640|yd|m|sigfig=3}}, scoring one hit amidships on ''Clan Ross''′s port side.<ref name=combinedfleetI6/> ''Clan Ross'' sank by the [[stern]] at 14:14 at {{coord|15|58|N|068|24|E|name=SS ''Clan Ross''}} with the loss of 11 crew members killed and three injured.<ref name=ijnsubsiteI6/><ref name=combinedfleetI6/> ''I-6'' surfaced and approached the survivors.<ref name=combinedfleetI6/> ''I-6''′s crew interrogated the survivors, provided them with [[fresh water]] and [[biscuit]]s, and gave them the [[Bearing (navigation)|bearing]] to Bombay, then lined up on ''I-6''′s afterdeck, saluted the survivors, and wished them "''bon voyage''" in broken [[French language|French]].<ref name=combinedfleetI6/>

While on the surface at around 16:00 on 7 April 1942, ''I-6'' encountered the British 5,424-ton [[merchant ship]] ''Bahadur'' — bound from Bombay to [[Basra]], [[Iraq]], with a cargo of 5,100 tons of government stores and ammunition — in the Arabian Sea {{convert|170|nmi}} northwest of Bombay.<ref name=ijnsubsiteI6/><ref name=combinedfleetI6/> ''I-6'' submerged and fired torpedoes, but ''Bahadur''′s crew spotted them and ''Bahadur'' made a hard turn to starboard, evaded the torpedoes, and attempted to open the range at top speed.<ref name=combinedfleetI6/> ''I-6'' fired two torpedoes from her stern [[torpedo tube]]s, but they also missed.<ref name=combinedfleetI6/> She then surfaced and pursued ''Bahadur'', opening fire with her {{convert|127|mm|in|adj=on|sp=us|0}} deck gun at a range of {{convert|6,570|yd|m|sigfig=3}}.<ref name=combinedfleetI6/> The gun jammed after firing only one round, and ''I-6'' submerged and gave up the chase.<ref name=combinedfleetI6/> ''Bahadur'' suddenly stopped, however, and lowered her [[Lifeboat (shipboard)|lifeboats]].<ref name=combinedfleetI6/> ''I-6'' closed and fired two more torpedoes from a position on ''Bahadur''′s port beam.<ref name=combinedfleetI6/> ''Bahadur'' sank by the stern at 19:20 at {{coord|19|44|N|068|28|E|name=''Bahadur''}}.<ref name=ijnsubsiteI6/><ref name=combinedfleetI6/>

''I-6'' surfaced in the Arabian Sea {{convert|300|nmi}} southwest of Bombay after 08:15 on 10 April 1942 to attack two 150-ton [[dhow]]s with her deck gun, claiming both of them sunk.<ref name=ijnsubsiteI6/><ref name=combinedfleetI6/> Her patrol ended with her arrival at [[Seletar]], [[Singapore]], on 17 April 1942.<ref name=combinedfleetI6/> She departed Singapore on 21 April 1942 in company with ''I-5'' to head for Yokosuka, which she reached on 1 May 1942.<ref name=combinedfleetI6/> She underwent repairs there until 6 June 1942.<ref name=combinedfleetI6/>

====Fourth war patrol====

While ''I-6'' was at Yokosuka, the [[Aleutian Islands campaign]] began on 3–4 June 1942 with a [[Battle of Dutch Harbor|Japanese air raid]] on [[Dutch Harbor]], [[Territory of Alaska|Alaska]], followed quickly by the unopposed Japanese occupation in the [[Aleutian Islands]] of [[Attu Island|Attu]] on 5 June and [[Kiska]] on 7 June 1942.<ref name=combinedfleetI6/> On 10 June 1942, ''I-1'', ''I-2'', ''I-3'', ''I-4'', ''I-5'', ''I-6'', and ''I-7'' were reassigned to the Northern Force for duty in the Aleutians, and on either 17 or 20 June 1942 ''I-6'' set out for Aleutian waters to begin her fourth war patrol.<ref name=combinedfleetI6/> She joined the "K" patrol line in the [[Unimak Pass]] area.<ref name=combinedfleetI6/> On 7 July 1942, she received orders to move to the Kiska area.<ref name=combinedfleetI6/> When the rest of Submarine Squadron 2 was ordered to return to Japan on 20 July 1942, she was ordered to remain behind and operate from Kiska.<ref name=combinedfleetI6/>

On 29 July 1942, an Imperial Japanese Navy [[Kawanishi H6K]] (Allied reporting name "Mavis") [[flying boat]] reported an American [[seaplane tender]] at [[Natan Bay]] on the coast of [[Adak Island]].<ref name=combinedfleetI6/> ''I-6'' went to investigate, but found nothing.<ref name=combinedfleetI6/> She was anchored off Kiska along with the submarines {{ship|Japanese submarine|Ro-61||2}}, {{ship|Japanese submarine|Ro-64||2}}, and {{ship|Japanese submarine|Ro-68||2}} when the [[cruiser]]s and destroyers of U.S. Navy [[Task Group]] 8.6 bombarded the island and harbor on 7 August 1942.<ref name=combinedfleetI6/> All four submarines submerged to avoid damage, and some of them set off in pursuit of the task group after the shelling ceased, but none succeeded in finding the withdrawing American ships.<ref name=combinedfleetI6/>

On 15 August 1942, ''I-6'' received orders to return to Japan, and she got underway from Kiska the same day.<ref name=combinedfleetI6/> While she was at sea, both Submarine Squadron 2 and Submarine Division 8 were disbanded, and she and ''I-5'' were reassigned to Submarine Division 7.<ref name=combinedfleetI6/> She arrived at Yokosuka on 23 August 1942 and began an overhaul.<ref name=combinedfleetI6/>

====August 1942–February 1943====
While ''I-6'' was at Kiska, the six-month [[Guadalcanal campaign]] began on 7 August 1942 with U.S. amphibious landings on [[Guadalcanal]], [[Tulagi]], [[Florida Island]], [[Gavutu]], and [[Tanambogo]] in the southeastern [[Solomon Islands (archipelago)|Solomon Islands]].<ref name=combinedfleetI6/> As the campaign wore on, the Japanese decided to use submarines to supply their forces fighting on Guadalcanal and began fitting the submarines involved in the supply runs with a mounting on their decks that allowed each of them to carry a [[Waterproofing|waterproofed]] [[Daihatsu-class landing craft|''Daihatsu''-class]] [[landing craft]] for the discharge of cargo along coastlines in the Solomon Islands.<ref name=combinedfleetI6/> ''I-6'' received a ''Daihatsu'' mounting during her overhaul,<ref name=combinedfleetI6/> but was still in Japan when [[Operation Ke]], the evacuation of Japanese forces on Guadalcanal, was completed on 7 February 1943, bringing the Guadalcanal campaign to an end.

With her overhaul complete, ''I-6'' departed Yokosuka at 10:00 on 16 February 1943 carrying a ''Daihatsu''.<ref name=combinedfleetI6/> She arrived at [[Chuuk Lagoon|Truk]] at 10:15 on 23 February 1943, and later that day the commander of Submarine Squadron 7 came aboard to inspect her.<ref name=combinedfleetI6/> On 26 February 1943 she disembarked her ''Daihatsu'' and took on fuel, supplies, and ammunition from ''Hie Maru''.<ref name=combinedfleetI6/> She departed her anchorage at 08:00 on 28 February 1943, made a test cruise off [[Uman Island]], and returned at 15:00.<ref name=combinedfleetI6/>

====Fifth war patrol====
On 2 March 1943, ''I-6'' got underway from Truk for her fifth war patrol, tasked with laying nine German-made TMC [[magnetic mine]]s off [[Brisbane]], [[Australia]], and patrolling in the [[South Pacific Ocean]] off the east coast of Australia.<ref name=combinedfleetI6/> On 4–5 March 1943, she transited [[St. George's Channel (Papua New Guinea)|St. George's Channel]] off [[New Ireland (island)|New Ireland]] southbound.<ref name=combinedfleetI6/> On 8 March 1943, [[FRUMEL|Fleet Radio Unit, Melbourne (FRUMEL)]], an American-Australian-British [[signals intelligence]] unit headquartered at [[Melbourne]], Australia, decrypted a Japanese message — probably one transmitted on 2 March — that revealed ''I-6''′s departure.<ref name=combinedfleetI6/>

By 12:00 on 11 March 1943, ''I-6'' was {{convert|60|nmi}} northeast of Brisbane.<ref name=combinedfleetI6/> At 17:15 that day she sighted a 10,000-ton Allied merchant ship<ref name=combinedfleetI6/> — probably a [[Liberty ship]]<ref name=powellp12>Powell, p. 12.</ref> — and at 18:44 fired two torpedoes at long range, which both missed.<ref name=combinedfleetI6/><ref name=powellp12/> The merchant ship apparently did not sight the torpedo [[wake (physics)|wake]]s and did not report an attack.<ref name=powellp12/> On 12 March 1943, ''I-6'' conducted a reconnaissance of [[Moreton Bay]], [[Caloundra Head]], and the approaches to Brisbane<ref name=combinedfleetI6/> to determine a good location to lay her mines. At 12:00 on 13 March 1943, she was northeast of Caloundra Head at {{coord|26|42|S|153|20|E}},<ref name=combinedfleetI6/> and that evening between 18:50 and 19:14, using a device that allowed her to eject mines via her forward torpedo tubes, she laid all nine mines within {{convert|6|nmi}} of the Australian coast along a {{convert|2,000|m|yd|adj=on|sp=us|sigfig=2}} line at depths of {{convert|24|to|34|m|ft|sp=us|0}} in what her commanding officer believed was a [[shipping lane]].<ref name=combinedfleetI6/><ref name=powellp12/> She then withdrew into the open ocean,<ref name=combinedfleetI6/> and later that evening transmitted a report of her activities.<ref name=powellp12/> FRUMEL intercepted and partially decrypted her message, learning that a Japanese submarine had laid nine mines somewhere along the east coast of Australia, but not the location of the mines because of code words ''I-6'' had used to describe their locations.<ref name=powellp12/> An attempt to determine the submarine's position at the time of the transmission using [[triangulation]] yielded nothing more precise than a nearly useless {{convert|500|nmi|adj=on|0}} circle.<ref name=powellp12/>

FRUMEL's reporting prompted instructions to [[coastal artillery]] forces to watch for a Japanese submarine and the [[Royal Australian Air Force]] (RAAF) stepped up its patrol efforts along the east coast of Australia, using [[Avro Anson]] and [[Bristol Beaufort]] aircraft.<ref name=powellp12/> ''I-6'' was forced to remain submerged during daylight hours by the increased RAAF activity,<ref name=powellp13>Powell, p. 13.</ref> but she patrolled uneventfully between [[Fraser Island]] and [[Stradbroke Island]] from 14 to 16 March 1943.<ref name=combinedfleetI6/> At 12:00 on 17 March 1943 she was southeast of [[Sandy Cape]] at {{coord|25|49|S|153|49|E}}.<ref name=combinedfleetI6/> At 14:30 she sighted the two-ship Convoy BT-44 — which consisted of the armed Liberty ships {{SS|Charles C. Jones||2}} and {{SS|Joseph Holt||2}} escorted by the [[Royal Australian Navy]] [[minesweeper]]-[[corvette]] {{HMAS|Gympie}} — just north of [[Point Cartwright Light|Point Cartwright]].<ref name=combinedfleetI6/><ref name=powellp13/> She fired two [[Japanese_53_cm_torpedo#Type_89|Type 89 torpedo]]es at ''Charles C. Jones'' at long range at 15:07, and at 15:11 ''Charles C. Jones'' sighted their wakes passing {{convert|20|yd|m|0}} astern of her.<ref name=combinedfleetI6/><ref name=powellp13/> ''Charles C. Jones'' and ''Joseph Holt'', which both turned to avoid the torpedoes, opened fire to alert ''Gympie''.<ref name=combinedfleetI6/><ref name=powellp13/> An Anson of the RAAF's [[No. 71 Squadron RAAF|No. 71 (Reserve) Squadron]] patrolling overhead also sighted the wakes and dropped a sea marker at ''I-6''′s presumed location.<ref name=combinedfleetI6/> ''Gympie'' and the Anson then searched for ''I-6'' until 15:30, and the Anson dropped a [[depth charge]] at 15:32, but ''I-6'' escaped unscathed.<ref name=combinedfleetI6/> At 20:22, she transmitted a situation report which FRUMEL intercepted and partly decrypted, and as a result two U.S. Navy [[patrol vessel]]s arrived in the area and searched for her until sunset on 18 March 1943, but without success.<ref name=combinedfleetI6/>

''I-6'' was off [[Cape Byron]] on 21 March 1943 when she received orders to depart her patrol area and proceed to [[Rabaul]].<ref name=combinedfleetI6/> She sent a situation report at 19:33 that evening which FRUMEL partially decrypted.<ref name=combinedfleetI6/> The Allied interception of ''I-6''′s enciphered communications had led the U.S. Navy to order three submarines — {{USS|Stingray|SS-186}}, {{USS|Halibut|SS-232}}, and {{USS|Trigger|SS-237}} — to lie in wait for ''I-6'' during her patrol, but none of them sighted her,<ref>Boyd and Yoshida, pp. 113–114.</ref> and she arrived at Rabaul at 07:30 on 27 March 1943.<ref name=combinedfleetI6/>

Unfortunately for the Japanese, ''I-6''′s commanding officer lacked adequate intelligence on Allied shipping patterns when ''I-6'' laid her mines, which were planted in an area rarely visited by Allied ships.<ref name=powellp13/> They went unnoticed until 24 March 1943, when the Royal Australian Navy [[sloop-of-war]] {{HMAS|Swan|U74|6}} visited the area to conduct [[antiaircraft gun]]nery practice, firing at a target towed by an RAAF [[Lockheed Hudson]].<ref name=powellp13/> As spent shells and shell fragments fell into the water, ''Swan'' observed two large explosions close aboard which reached {{convert|400|ft|m|0}} in height and {{convert|130|ft|m|0}} across their bases.<ref name=powellp13/> At least two mines clearly had exploded, and the size of the explosions suggested that each of them separately may have represented the detonation of two mines, although Allied forces could not substantiate this possibility.<ref name=powellp13/> ''Gympie'' arrived in the area and began a [[minesweeping]] effort that after a number of days detonated another mine, but repeated sweeping found no more by the time minesweeping operations ended in September 1943.<ref name=combinedfleetI6/><ref name=powellp13/> The mines were designed to rest on the seafloor and were not fixed in place, meaning that they could slide or roll if laid on sloping surfaces, and the Allies found the mines in a somewhat different location — {{convert|8|nmi}} offshore in waters {{convert|30|to|40|m|ft|sp=us|0}} deep<ref name=powellp13/> — than ''I-6'' reported laying them.

====New Guinea campaign====
While ''I-6'' was on patrol, a Japanese attempt to carry supplies and reinforcements to [[New Guinea]] for their forces fighting in the [[New Guinea campaign]] in a convoy of eight ships escorted by eight destroyers ended in disaster in the [[Bismarck Sea]] when Allied aircraft sank all eight ships and four of the destroyers in the [[Battle of the Bismarck Sea]], fought from 2 to 4 March 1943.<ref name=combinedfleetI6/> The Japanese decided to use submarines instead to carry supplies and troops to New Guinea.<ref name=combinedfleetI6/> Accordingly, on 29 March 1943 ''I-6'' was reassigned to the [[Southeast Area Fleet]] for duty running supplies to [[Lae]] on the coast of New Guinea.<ref name=combinedfleetI6/> She got underway from Rabaul for her first supply run on 3 April 1943, carrying 30 passengers and 77 supply drums containing 3.3 tons of weapons and ammunition, 22 tons of clothing, and 15.4 tons of food.<ref name=combinedfleetI6/> She arrived at [[Lae]] on the coast of New Guinea on 5 April 1943, where she disembarked her passengers and discharged her cargo onto ''Daihatsus''.<ref name=combinedfleetI6/> She brought aboard four [[Imperial Japanese Army]] soldiers who were taking the [[regimental colors]] of the [[41st Infantry Regiment (Imperial Japanese Army)|41st Infantry Regiment]] to Rabaul and 25 other passengers and departed for Rabaul.<ref name=combinedfleetI6/> Shortly after her departure she sighted Allied [[motor torpedo boat]]s, but she crash-dived and avoided them and arrived safely at Rabaul on 7 April 1943.<ref name=combinedfleetI6/>

''I-6'' next called at Lae on 11 April 1943, unloading 26 passengers and 77 supply drums containing 4.4 tons of weapons and ammunition, 19 tons of clothing, and food and embarking 42 passengers for Rabaul.<ref name=combinedfleetI6/> On her third supply run, she visited Lae on 17 April 1943, discharging 28 passengers and 77 supply drums containing four tons of weapons and ammunition and 17 tons of clothing.<ref name=combinedfleetI6/> After embarking 39 passengers, she got back underway for Rabaul.<ref name=combinedfleetI6/> She sighted Allied motor torpedo boats near the [[Tami Islands]] during the return trip, but submerged and avoided them.<ref name=combinedfleetI6/> While at Rabaul, she was reassigned on 21 April 1943 to the Northern District Force in the [[5th Fleet (Imperial Japanese Navy)|5th Fleet]] to support the supply and reinforcement of the Japanese garrisons on Attu and Kiska in the Aleutian Islands.<ref name=combinedfleetI6/>

''I-6''′s redeployment to the North Pacific was deferred, and for the time being she continued her supply runs between Rabaul and Lae. On her fourth run, she delivered 20 passengers and supply drums containing one ton of ammunition, 16 tons of clothing, and 16 tons of food on 24 April 1943 and left for Rabaul with 42 passengers aboard.<ref name=combinedfleetI6/> She visited Lae on her fifth run on 30 April 1943 and dropped off 30 passengers and supply drums holding three tons of weapons and ammunition, 19 tons of clothing, and one ton of food.<ref name=combinedfleetI6/> She embarked 41 passengers and put back to sea.<ref name=combinedfleetI6/> At dawn she sighted Allied motor torpedo boats and spent an hour evading them, but she arrived safely at Rabaul.<ref name=combinedfleetI6/> On her sixth run, she called at Lae on 7 May 1943 to deliver 10 passengers and 77 supply drums carrying 2.8 tons of weapons, four tons of artillery shells, and 13 tons of clothing and pick up 12 passengers.<ref name=combinedfleetI6/>

''I-6''′s seventh run was more eventful. She arrived at Lae on 13 May 1943, unloaded 10 passengers and supply drums containing 11.5 tons of weapons, five tons of ammunition, and nine tons of food.<ref name=combinedfleetI6/> After embarking four passengers, she began her return trip to Rabaul.<ref name=combinedfleetI6/> Shortly thereafter, the U.S. Navy [[PT boat]]s {{ship|Patrol torpedo boat|PT-150||2}} and {{ship|Patrol torpedo boat|PT-152||2}} sighted ''I-6'' making {{convert|12|kn}} on the surface {{convert|5|nmi}} off Lae at a range of {{convert|6,000|yd|m|sigfig=2}}.<ref name=combinedfleetI6/> Each PT boat fired two torpedoes at ''I-6'' at long range, but ''I-6'' stopped and the torpedoes missed ahead of her.<ref name=combinedfleetI6/> ''PT-150'' then closed to {{convert|4,000|yd|m|sigfig=2}} and fired another torpedo at the stationary ''I-6'', but the submarine suddenly accelerated and the torpedo missed astern.<ref name=combinedfleetI6/> The PT boats then ran parallel to ''I-6''′s course and turned toward her to decrease the range, but she submerged.<ref name=combinedfleetI6/> The PT boats then stopped, and ''I-6'' fired a torpedo at them, which passed under ''PT-150''′s [[Bow (ship)|bow]] without detonating, bringing the action to a close.<ref name=combinedfleetI6/> ''I-6'' proceeded with her voyage to Rabaul, but on 14 May 1943 she diverted from it so that she and ''I-5'' could search for the crews of [[Mitsubishi G4M]] (Allied reporting name "Betty") [[bomber]]s shot down during a raid on [[Oro Bay]].<ref name=combinedfleetI6/> She rescued two aviators from the water {{convert|60|nmi}} off [[Buna, Papua New Guinea|Buna]], New Guinea.<ref name=combinedfleetI6/>

On her eighth run, ''I-6'' called at Lae on 21 May 1943 to deliver 5.1 tons of weapons, 5.4 tons of ammunition, 4.6 tons of food, and 31 passengers.<ref name=combinedfleetI6/> She departed for Rabaul after embarking 40 passengers.<ref name=combinedfleetI6/> On her ninth and final run, she visited Lae on 28 May 1943 and dropped off 18 tons of food, 4.3 tons of weapons and medicine, two tons of clothes, a ''Daihatsu'', and 23 passengers.<ref name=combinedfleetI6/> Not scheduled to return to Rabaul, she did not embark passengers.<ref name=combinedfleetI6/> She instead got back underway bound directly for Truk.<ref name=combinedfleetI6/> Reassigned along with ''I-5'' to the 6th Fleet while at sea on 31 May 1943, she stopped at Truk from 1 to 2 June 1943, then proceeded to Yokosuka, which she reached on 8 June 1943.<ref name=combinedfleetI6/> She underwent repairs there.<ref name=combinedfleetI6/>

====Sixth and seventh war patrols====
In the Aleutian Islands, the Japanese garrison on Attu had been annihilated by invading U.S. forces in the [[Battle of Attu]] between 11 and 30 May 1943. On 21 May 1943, with the situation on Attu deteriorating, the Japanese [[Imperial General Headquarters]] decided to evacuate the isolated garrison on Kiska.<ref name=combinedfleetI6/> The evacuation began by submarine on 26 May 1943.<ref name=combinedfleetI6/> Submarine Division 7 was reassigned to the 5th Fleet on 1 July 1943, and on either 1 or 2 July ''I-6'' set out from Yokosuka on her sixth war patrol, bound for [[Paramushiro]] in the [[Kuril Islands]].<ref name=combinedfleetI6/> After calling at Paramushiro, she deployed to support the ongoing evacuation of Kiska, patrolling with ''I-5'' in the [[Bering Sea]] north-northeast of Kiska.<ref name=combinedfleetI6/> Between 17 and 19 July 1943, the two submarines sighted three U.S. destroyers on three separate occasions, but were unable to attack them.<ref name=combinedfleetI6/> The Japanese completed the evacuation on 28 July 1943, and ''I-6'' concluded her patrol with her arrival at Paramushiro on 4 August 1943.<ref name=combinedfleetI6/>

''I-6'' departed Paramushiro on 16 August 1943 for her seventh war patrol, assigned a patrol area off Kiska.<ref name=combinedfleetI6/> The patrol was uneventful, and she returned to Paramushiro on 3 September 1943.<ref name=combinedfleetI6/> She got back underway on 5 September 1943 and arrived on 10 September at Yokosuka, where she underwent repairs.<ref name=combinedfleetI6/>

====New Guinea and Bismarck Archipelago====
On 25 October 1943, ''I-6'' was reassigned to the Southeast Area Fleet to resume duties on supply runs to New Guinea and in the [[Bismarck Archipelago]].<ref name=combinedfleetI6/> On 30 October, she departed Yokosuka bound for Rabaul.<ref name=combinedfleetI6/> From Rabaul, she began supply runs to [[Sio, Papua New Guinea|Sio]] on the [[Huon Peninsula]] in New Guinea, calling at Sio on 16 November and 4 December 1943 without incident but coming under attack by Allied aircraft during her third visit on 18 December 1943 while unloading cargo; the attack forced her to depart before she could completely unload, and she returned to Rabaul with some cargo still aboard.<ref name=combinedfleetI6/> She visited Sio for the fourth and final time on 27 December 1943 and early in the morning, just after she began her return voyage to Rabaul, she encountered Allied motor torpedo boats, which depth-charged her.<ref name=combinedfleetI6/> Later that day, Allied aircraft attacked her.<ref name=combinedfleetI6/> She emerged from both attacks unscathed, and on the same day received orders to intercept an Allied convoy.<ref name=combinedfleetI6/> With only two torpedoes aboard, she patrolled in the [[Dampier Strait (Papua New Guinea)|Dampier Strait]] from 28 December 1943 to 1 January 1944, but did not find the Allied ships.<ref name=combinedfleetI6/>

On 4 January 1944, ''I-6'' began a new series of supply runs, shuttling between Rabaul and [[Iboki]], New Guinea.<ref name=combinedfleetI6/> Her first and second round trips — from 4 to 10 January 1944, calling at Iboki on 6 January, and from 17 to 21 January 1944, calling at Iboki on 19 January — involved the delivery of supplies.<ref name=combinedfleetI6/> On her third run, in which she departed Rabaul on 28 January 1944, she carried only troops, which she disembarked at Iboki on 30 January 1944, damaging her [[Propeller|screws]] on an uncharted [[reef]] in the process.<ref name=combinedfleetI6/> She returned to Rabaul on 1 February 1944, and on that day Submarine Division 7 was attached directly to 6th Fleet [[Headquarters unit|headquarters]].<ref name=combinedfleetI6/> Her next supply trip saw her depart Rabaul on 3 February 1944 to deliver supplies to [[Sarmi Regency|Sarmi]], New Guinea.<ref name=combinedfleetI6/> She received orders on 5 February 1944 to return to Yokosuka.<ref name=combinedfleetI6/> She got underway from Rabaul on 13 February 1944, called at [[Lorengau]] on [[Manus Island]] in the [[Admiralty Islands]] on 17 February 1944 to deliver a cargo of 12 heavy [[machine gun]]s and their ammunition, then departed the same day for Yokosuka, which she reached on 29 February 1944 to begin an overhaul.<ref name=combinedfleetI6/>

====Loss====
On 15 June 1944, the [[Marianas campaign]] began with the [[Battle of Saipan|U.S. invasion]] of [[Saipan]]. Anticipating the invasion, on 13 June 1944 the commander of the 6th Fleet, Vice Admiral [[Takeo Takagi]], ordered all available Japanese submarines to deploy east of the [[Mariana Islands]].<ref name=combinedfleetI6/> With her overhaul recently completed, ''I-6'' set out from Yokosuka bound for the waters off Saipan on 16 June 1944. At 22:33 that evening the Japanese 5,123-ton armed [[cargo ship]] ''Toyokawa Maru'' — a member of Convoy 3606, consisting of four merchant ships escorted by three [[Kaibōkan|coastal defense ships]] and a [[submarine chaser]], which had left [[Ogasawara, Tokyo|Ogasawara]] in the [[Bonin Islands]] on 14 June 1944 bound for Yokosuka<ref name=combinedfleetI6/> — sighted ''I-6'' surfacing near the convoy.<ref name=combinedfleetI6/> Mistaking her for an enemy submarine, ''Toyokawa Maru'' sounded a submarine alert, turned sharply toward ''I-6'', and rammed her on her starboard side just abaft her conning tower.<ref name=combinedfleetI6/> ''I-6'' listed heavily, [[capsize]]d, and sank a few minutes later, and ''Toyokawa Maru'' followed up by dropping depth charges and machine gunning the water where ''I-6'' sank.<ref name=combinedfleetI6/> None of ''I-6''′s crew of 104 survived.<ref name=ijnsubsiteI6/><ref name=combinedfleetI6/>

On 1 July 1944, the Japanese ordered ''I-6'' to rescue Takagi and his staff from their headquarters on Saipan, which was threatened by advancing American forces.<ref name=combinedfleetI6/> When ''I-6'' did not acknowledge receipt of the message, the Japanese declared her missing.<ref name=combinedfleetI6/> Sixth Fleet headquarters made a final attempt to contact her on 3 July 1944.<ref name=combinedfleetI6/>

Alternative accounts of the loss of ''I-6'' claim that ''Toyokawa Maru'' sank her off Saipan on 30 June 1944,<ref name=powellp13/> or that the [[destroyer escort]] {{USS|William C. Miller|DE-259}} and [[high-speed transport]] {{USS|Gilmer|APD-11}} sank her {{convert|70|nmi}} west of [[Tinian]] at {{coord|15|18|N|144|26|E}} on 19 July 1944.<ref name=powellp13/>

''I-6'' was stricken from the Navy list on 10 September 1944.<ref name=combinedfleetI6/>

==References==
===Footnotes===
{{Reflist}}

===Bibliography===
*Boyd, Carl, and Akihiko Yoshida. ''The Japanese Submarine Force and World War II''. Annapolis, Maryland: Naval Institute Press, 1995. {{ISBN|1-55750-015-0}}.
*[https://issuu.com/vmrsandgate/docs/2011-12_feb_march_boat_talk_no_crews Powell, Arthur. "War Comes to the Brisbane Sea Approaches, March 1943: Via the IJN Submarine ''I-6''." ''Boat Talk''. February–March 2012.]

{{Junsen type submarine}}
{{1935 shipwrecks}}
{{February 1942 shipwrecks}}
{{January 1944 shipwrecks}}
{{June 1944 shipwrecks}}

{{DEFAULTSORT:I-006}}
[[Category:Junsen type submarines]]
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[[Category:Ships of the Aleutian Islands campaign]]
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