View source for Japanese submarine I-177

{|{{Infobox ship begin}}
{{Infobox ship image
|Ship image=I-176.jpg
|Ship caption=''I-176'', lead submarine of the class that included ''I-177''
}}
{{Infobox ship career
|Hide header=
|Ship country= [[Empire of Japan]]
|Ship flag=[[Image:Naval Ensign of Japan.svg|60px]]
|Ship name= ''Submarine No. 155''
|Ship namesake=
|Ship ordered=
|Ship builder=[[Kawasaki Shipbuilding Corporation|Kawasaki]], [[Kobe]],&nbsp;[[Japan]]
|Ship laid down=10 March 1941
|Ship renamed=''I-77'' on 17&nbsp;December&nbsp;1941
}}
{{Infobox ship career
|Hide header=yes
|Ship launched=20 December 1941
|Ship renamed=''I-177'' on 20 May 1942
}}
{{Infobox ship career
|Hide header=yes
|Ship acquired=
|Ship commissioned= 28 December 1942
|Ship decommissioned=
|Ship in service=
|Ship out of service=
|Ship struck=
|Ship reinstated=
|Ship fate=Sunk 3 October 1944
}}
{{Infobox ship career
|Hide header=yes
|Ship struck=1 March 1945
}}
{{Infobox ship characteristics
|Hide header=
|Header caption=
|Ship class=[[Kaidai type submarine|''Kaidai'' type]], [[Kaidai type submarine#Kaidai VII (I-176 class)|''KD7''-class]]
|Ship displacement=*1,630&nbsp;[[long ton]]s (1,656 [[Tonne|t]]) surfaced
*2,602&nbsp;[[long ton]]s (2,644 [[Tonne|t]]) submerged
|Ship length={{convert|105.5|m|ftin|abbr=on}}
|Ship beam={{convert|8.25|m|ftin|abbr=on}}
|Ship draught=
|Ship draft={{convert|4.6|m|ftin|abbr=on}}
|Ship propulsion=*2 × Kampon Mk.1B Model 8 diesels, 2 shafts; {{convert|8,000|bhp|0|abbr=on}}
*Electric motors: {{convert|1,800|shp|0|abbr=on}}
|Ship speed=*{{convert|23.1|kn|lk=in}} surfaced
*{{convert|8|kn}} submerged
|Ship range=*{{convert|8000|nmi|lk=in|abbr=on}} at {{convert|16|kn}} surfaced
*{{convert|50|nmi|abbr=on}} at {{convert|5|kn}} submerged
|Ship endurance=
|Ship test depth={{convert|80|m|ft|0|abbr=on}}
|Ship complement=86
|Ship sensors=
|Ship EW=
|Ship armament=*6 × 533&nbsp;mm forward [[torpedo tube]]s
*12 × [[Type 95 torpedo]]es
*1 × [[12 cm 11th Year Type naval gun|{{convert|120|mm|in|abbr=on}}]] 11th Year Type Naval gun
*2 × [[Type 96 25 mm AT/AA Gun|Type 96 25mm AA guns]]
|Ship aircraft=
|Ship notes=
}}
|}

'''''I-177''''' was an [[Imperial  Japanese Navy]] [[Kaidai type submarine|''Kaidai''-type]] [[cruiser submarine]] of the KD7 [[ship class|subclass]] commissioned in 1942. She served during [[World War II]], patrolling off [[Australia]], taking part in the [[New Guinea campaign]], operating in the [[North Pacific]], and participating in the [[Mariana and Palau Islands campaign|Palau campaign]] before she was sunk by the [[destroyer escort]] {{USS|Samuel S. Miles|DE-183}} in 1944, with no survivors.

==Construction and commissioning==
Built by [[Kawasaki Shipbuilding Corporation|Kawasaki]] at [[Kobe]], [[Japan]], the [[submarine]] was [[Keel-laying|laid down]] as ''Submarine No. 155'' on 10 March 1941.<ref name=ijnsubsiteI177>[http://www.ijnsubsite.info/I-Sub%20Details/I-177.htm I-177 ijnsubsite.com 9 June 2018 Accessed 13 February 2022]</ref><ref name=combinedfleetI177>{{cite web |url= http://www.combinedfleet.com/I-177.htm |title=IJN Submarine I-177: Tabular Record of Movement |first1=Bob |last1=Hackett |first2=Sander |last2=Kingsepp |work=combinedfleet.com |date=2 September 2015|access-date=13 February 2022}}</ref> She was both renumbered '''''I-77''''' and attached provisionally to the [[Sasebo Naval District]] on 17 December 1941.<ref name=combinedfleetI177/> [[Ceremonial ship launching|Launched]] on 20 December 1941,<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> she was renumbered '''''I-177''''' on 20 May 1942.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She was completed and [[Ship commissioning|commissioned]] on 28 December 1942.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/>

== Service history ==
===December 1942–April 1943===
Upon commissioning, ''I-177'' was assigned to the Kure Submarine [[Squadron (naval)|Squadron]] in the [[Kure Naval District]].<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> On 25 February 1943, she was reassigned to Submarine [[Division (naval)|Division]] 22, which in turn was assigned directly to the [[6th Fleet (Imperial Japanese Navy)|6th Fleet]], an element of the [[Combined Fleet]].<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> Submarine Division 22 was reassigned to Submarine Squadron 3 in the 6th Fleet on 15 March 1943.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> On 30 March 1943, ''I-177'' departed [[Kure, Hiroshima|Kure]], Japan, in company with her [[sister ship]] {{ship|Japanese  submarine|I-178||2}} bound for [[Chuuk Atoll|Truk Atoll]], which she reached on 7 April 1943.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/>

===First war patrol: AHS ''Centaur''===

''I-177'' got underway from Truk on 10 April 1943, assigned a patrol area off the east coast of [[Australia]] together with ''I-178'' and the submarine {{ship|Japanese submarine|I-180||2}}.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She was near [[Brisbane]], {{convert|20|nmi}} southeast of [[Cape Byron]] on 26 April 1943 when she attacked an [[Allies of World War II|Allied]] [[convoy]] and sank the British [[cargo ship]] ''Limerick'' at {{coord|28|54|S|153|54|E|name=''Limerick''}}.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> The convoy′s escorts counterattacked, dropping two [[depth charge]]s, but ''I-177'' escaped damage.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/>

During the predawn hours of 14 May 1943, ''I-177'', operating on the surface {{convert|40|nmi}} east of [[Brisbane]], sighted the 3,222-ton Australian [[hospital ship]] {{ship|AHS|Centaur||6}} {{convert|24|nmi}} east-northeast of [[North Stradbroke Island]].<ref name=combinedfleetI177/><ref>Edwards, pp. 59, 62.</ref> ''Centaur'' had departed [[Sydney]], [[Australia]], on 12 May 1943 bound for [[Port Moresby]], [[New Guinea]], via [[Cairns]], Australia, to evacuate sick and wounded personnel during fighting in the [[New Guinea campaign]],<ref name=combinedfleetI177/><ref name=edwardsp59>Edwards, p. 59.</ref> and was steaming northward in darkness<ref name=edwardsp59/> displaying the lights and markings required of a hospital ship in wartime under the [[Hague Conventions of 1899 and 1907|Hague Convention]],<ref name=edwardsp60>Edwards, p. 60.</ref> ''I-177'' nonetheless submerged to [[periscope depth]] and fired a [[torpedo]] at ''Centaur'' at 04:10 which struck her at 04:15.<ref name=combinedfleetI177/><ref name=edwardsp62>Edwards, p. 62.</ref><ref>{{harvnb|Dennis|Grey|2009|p=124}}</ref> The torpedo ignited a fuel tank, setting the ship ablaze.<ref name=edwardsp62/> ''Centaur'' rolled to port and sank within three minutes in {{convert|550|m|ft|0|sp=us}} of water at {{coord|27|17|S|154|05|E|name=AHS ''Centaur''}}.<ref name=combinedfleetI177/> ''I-177'' surfaced nearby, then departed the area.<ref name=combinedfleetI177/> ''Centaur''′s survivors drifted until 15 May 1943, hearing ''I-177''′s [[diesel engine]]s as she passed through the area of the sinking again on the surface in the early-morning darkness of 15 May, before a [[Royal Australian Air Force]] [[Avro Anson]] [[Maritime patrol aircraft|patrol aircraft]] sighted them clinging to debris.<ref name=combinedfleetI177/><ref name=edwards6465>Edwards, pp. 64–65.</ref> The [[United States Navy]] [[destroyer]] {{USS|Mugford|DD-389}} departed Brisbane to come to their assistance, arriving on the scene at 14:00 on 15 May and pulling them from the water.<ref name=combinedfleetI177/><ref name=edwards6465/> Of the 332<ref name=edwards6465/> or 333 (according to different sources) crew, patients, medical staff, and passengers on board ''Centaur'', only 64 survived.<ref name=combinedfleetI177/><ref name=edwards6465/> ''I-177'' concluded her patrol with her return to Truk on 23 May 1943.<ref name=combinedfleetI177/>

Following the end of the [[Pacific War]] in August 1945, Australian [[war crime]]s investigators investigated whether ''I-177'' and her [[commanding officer]], [[Commander]] Hajime Nakagawa, were responsible for sinking ''Centaur''. but they were unable to establish this beyond reasonable doubt. Several of the investigators suspected that Nakagawa and ''I-177'' were most likely responsible. Nakagawa survived the war and refused to speak on the subject of the sinking of ''Centaur'', even to defend himself. However, Nakagawa was charged with ordering the [[Machine gun|machine-gunning]] of survivors from torpedoed ships on three different dates in February 1944 while in command of the submarine {{ship|Japanese submarine|I-37||2}}. He was convicted and sentenced to four years imprisonment at [[Sugamo Prison]] as a Class B [[war criminal]]. He died in 1991.<ref name="Jenkins284-5">Jenkins, ''Battle Surface'', pp. 284–285</ref>

===Second war patrol===

''I-177'' departed Truk on 14 June 1943 to begin her second war patrol, again in an area off the east coast of Australia.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> Almost immediately after arriving off Australia, she received orders on 30 June 1943 to move to the [[Solomon Islands (archipelago)|Solomon Islands]] between [[Santa Isabel Island]] and the [[New Georgia Islands]] – where U.S. landings began the [[New Georgia campaign]] that day – to attack U.S. landing forces off [[Rendova Island]].<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She arrived in this new patrol area on 6 July 1943,<ref name=combinedfleetI177/> but her patrol was uneventful. On 20 July 1943, she was reassigned to the [[Southeast Area Fleet]],<ref name=combinedfleetI177/> and she concluded her patrol with her arrival at [[Rabaul]] on [[New Britain]] in the [[Bismarck Archipelago]] on 24 July 1943.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/>

===New Guinea campaign===
====Lae supply runs====
Upon arriving at Rabaul, ''I-177'' was assigned to the support of Japanese forces fighting on New Guinea in the New Guinea campaign. She departed Rabaul on 7 August 1943 to make her first supply run to New Guinea.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She arrived at [[Lae]], New Guinea, on 9 August,<ref name=combinedfleetI177/> unloaded her cargo there, and headed back to Rabaul, which she reached on 11 August 1943.<ref name=ijnsubsiteI177/> Her next supply run began with her departure from Rabaul on 22 August 1943;<ref name=ijnsubsiteI177/> she unloaded at Lae on 24 August<ref name=combinedfleetI177/> and returned to Rabaul on 26 August 1943.<ref name=ijnsubsiteI177/> On 30 August 1943, Nakagawa left ''I-177'' to take command of the submarine {{ship|Japanese submarine|I-37||2}},<ref>[https://www.ijnsubsite.info/Commander%20Details%20k-o/nakagawa_hajime.htm Nakagawa Hajime 中川 肇 ijnsubsite.com 29 June 2020 Accessed 14 February 2022]</ref> and Lieutenant Commander Zenji Orita became ''I-177''′s new commanding officer.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/>

''I-177'' began her third supply run on 1 September 1943, when she departed Rabaul in company with the submarine {{ship|Japanese submarine|Ro-106||2}} for another trip to Lae,<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> where she arrived on 3 September and unloaded her cargo.<ref name=combinedfleetI177/> She made port at Rabaul on 5 September 1943.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She put to sea from Rabaul on both 6 and 8 September 1943, returning the same evening on both occasions.<ref name=combinedfleetI177/>

''I-177'' got underway from Rabaul on 10 September 1943<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> for her fourth supply run to Lae, which was threatened by a nearby landing on the [[Huon Peninsula]] by the [[Australian Army]]′s [[9th Division (Australia)|9th Division]] that had taken place on 4 September 1943<ref name=combinedfleetI177/> as the [[Salamaua–Lae campaign]] neared its end. On 13 September, she received orders to divert to attack Allied landing forces at [[Finschhafen]], New Guinea, but she found no targets there and resumed her voyage to Lae.<ref name=combinedfleetI177/> By the time she reached Lae on 14 September 1943, it was under attack by Allied forces.<ref name=combinedfleetI177/> She unloaded her cargo and put back to sea, where during the evening of 14 September she detected the [[propeller]] noises of what her crew assessed as several U.S. Navy destroyers at a range of a few thousand yards while she was on the surface.<ref name=combinedfleetI177/> Assuming that the destroyers had detected her on [[radar]], she submerged to her [[test depth]] of {{convert|100|m|0|sp=us}} to await a depth-charge attack, but none came.<ref name=combinedfleetI177/> Orita concluded that the destroyers had failed to gain [[sonar]] contact on ''I-177'' because of her depth and the negative effect of [[thermocline]]s on sonar performance.<ref name=combinedfleetI177/> While ''I-177'' was at sea, Submarine Division 22 was disbanded on 15 September 1943, and she was reassigned directly to the 6th Fleet.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She returned to Rabaul on 17 September 1943,<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> completing the Imperial Japanese Navy′s last supply run to Lae.<ref name=combinedfleetI177/>

====Finschhafen====

On 19 September 1943, ''I-177'' departed Rabaul′s [[Simpson Harbour]] to conduct deep-diving tests, then returned to the harbor later in the day.<ref name=combinedfleetI177/> On 21 September, she got underway from Rabaul for a supply run to Finschhafen.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> While at sea, she received orders on 22 September to attack Allied landing forces in the Finschhafen area, so her crew dumped her deck cargo overboard and she headed for the landing area, which she reconnoitered on 23 September.<ref name=combinedfleetI177/> She did not attack any ships there, and proceeded to Finschhafen, where she unloaded the rest of her cargo on 24 September during lulls in Allied air attacks.<ref name=combinedfleetI177/> She again reconnoitered the landing area on 25 September 1943 and detected several Allied ships, but made no attacks.<ref name=combinedfleetI177/> She returned to Rabaul on 26 September 1943.<ref name=combinedfleetI177/>

====Sio supply runs====

On 2 October 1943,''I-177'' set out from Rabaul on her first supply run to [[Sio, Papua New Guinea|Sio]], New Guinea.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She arrived there on 4 October, unloaded her cargo,<ref name=combinedfleetI177/> and returned to Rabaul, which she reached on 6 October.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> On her second run, she departed Rabaul on 8 October,<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> unloaded at Sio on 10 October,<ref name=combinedfleetI177/> and returned to Rabaul on 12 October 1943.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> That day, the [[United States Army Air Forces]] [[Fifth Air Force]] attacked Rabaul in what at the time was the largest air raid of the Pacific war, with 349 aircraft striking Rabaul's airfields and [[Simpson Harbour]] off Rabaul.<ref name=combinedfleetI177/> Moored in deep water, ''I-177'' submerged and avoided damage during the raid.<ref name=combinedfleetI177/>

In October and November 1943, ''I-177'' continued to make supply runs to Sio, departing Rabaul on 19 October,<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> visiting Sio on 21 October,<ref name=combinedfleetI177/> and returning to Rabaul on 23 October;<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> getting underway from Rabaul on 26 October,<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> discharging cargo at Sio on 28 October,<ref name=combinedfleetI177/> and arriving at Rabaul on 30 October 1943;<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> putting to sea from Rabaul on 2 November,<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> delivering her cargo at Sio on 4 November,<ref name=combinedfleetI177/> and making port at Rabaul on 6 November 1943;<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> and leaving Rabaul on 9 November,<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> calling at Sio on 11 November,<ref name=combinedfleetI177/> and returning to Rabaul on 13 November 1943.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> On 20 November 1943, she departed Rabaul in company with the submarine {{ship|Japanese submarine|Ro-108||2}} for her seventh supply run to Sio,<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> where she unloaded her cargo on 22 November.<ref name=combinedfleetI177/> She returned to Rabaul on 24 November 1943.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/>

In the immediate aftermath of the [[Battle of Cape St. George]], fought on the night of 24–25 November 1943 in the waters between [[Buka Island]] and [[Cape St. George]] on [[New Ireland (island)|New Ireland]], ''I-177'' got underway from Rabaul on 25 November to search for survivors of the sunken destroyer {{ship|Japanese destroyer|Yugiri|1930|2}}; she rescued 279 men and the submarine {{ship|Japanese submarine|I-181||2}} rescued 11.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> As ''I-177'' returned to Rabaul, a U.S. Navy [[Lockheed Ventura|Lockheed PV-1 Ventura]] [[patrol bomber]] of [[VP-138|Patrol Squadron 138 (VP-138)]] attacked her off Cape St. George on 26 November 1943, but she avoided damage.<ref name=combinedfleetI177/> She returned to Rabaul later that day, loaded provisions, and put back to sea the same day,<ref name=ijnsubsiteI177/> then again returned to Rabaul on 29 November 1943.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/>

''I-177'' loaded supplies for New Guinea at Rabaul on 30 November 1943,<ref name=combinedfleetI177/> and returned to her routine of supply runs: She departed Rabaul on 3 December 1943,<ref name=ijnsubsiteI177/> called at Sio on 5 December,<ref name=combinedfleetI177/> and returned to Rabaul on 7 December,<ref name=ijnsubsiteI177/> then got back underway on 12 December 1943,<ref name=ijnsubsiteI177/> visited Sio on 14 December,<ref name=combinedfleetI177/> and returned to Rabaul on 15 December.<ref name=ijnsubsiteI177/> Once again bound for Sio, she departed Rabaul on 16 December 1943<ref name=ijnsubsiteI177/> and discharged her cargo at Sio on 17 December,<ref name=combinedfleetI177/> then conducted a brief patrol south of [[Marcus Bay]] on the coast of New Britain from 18 to 20 December<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> before returning to Rabaul on 21 December 1943.<ref name=ijnsubsiteI177/>

After leaving Rabaul on 23 December 1943<ref name=ijnsubsiteI177/> and discharging her cargo at Sio on 25 December 1943,<ref name=combinedfleetI177/> ''I-177'' sighted several Allied [[Amphibious warfare ship|amphibious landing ship]]s,<ref name=combinedfleetI177/> but did not attack them. She returned to Rabaul on 27 December 1943,<ref name=ijnsubsiteI177/> then put back to sea on 28 December<ref name=ijnsubsiteI177/> to make her first and only supply run to [[Garove Island]], where she arrived on 30 December 1943.<ref name=combinedfleetI177/> She again made port at Rabaul on 1 January 1944.<ref name=ijnsubsiteI177/>

On 3 January 1944, ''I-177'' departed Rabaul to begin her twelfth Sio supply run.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> While at sea, she was reassigned to Submarine Squadron 1 on 5 January 1944.<ref name=combinedfleetI177/> She arrived off Sio at sunset on 8 January 1944 and made contact with Japanese troops ashore.<ref name=combinedfleetI177/> A ''[[daihatsu]]'' [[barge]] came alongside and began loading cargo from ''I-177'', and a boat set out from shore carrying the commander of the [[Eighteenth Army (Japan)|18th Army]], [[General]] [[Hatazō Adachi]], the commander of the 7th Base Unit, [[Rear admiral|Rear Admiral]] [[Kyuhachi Kudo]], and ten of their staff officers.<ref name=combinedfleetI177/> Meanwhile, the U.S. Navy [[PT boat]] ''[[Patrol torpedo boat PT-146|PT-146]]'' detected ''I-177'' on [[radar]] at a range of {{convert|5,000|yd}} and headed toward ''I-177'' in company with ''[[Patrol torpedo boat PT-143|PT-143]]''.<ref name=combinedfleetI177/> One of ''I-177''′s lookouts spotted the approaching PT boats, prompting ''I-177'' to submerge and Adachi′s boat, which had made it about halfway to ''I-177'',  to return to shore.<ref name=combinedfleetI177/> The two PT boats continued to search the area, later making a radar contact at a range of {{convert|1|nmi}} and sighting ''I-177''′s [[periscope]] at a range of {{convert|200|yd}}.<ref name=combinedfleetI177/> Each of them dropped two depth charges, but ''I-177'' escaped damage.<ref name=combinedfleetI177/>

''I-177'' returned to Sio on the evening of 9 January 1944, but again found U.S. PT boats in the area, so she signaled Japanese forces on New Guinea that she would return on the evening of 10 January and requested their support in driving off the PT boats.<ref name=combinedfleetI177/> When she surfaced off Sio on 10 January, the PT boats ''[[Patrol torpedo boat PT-320|PT-320]]'' and ''[[Patrol torpedo boat PT-323|PT-323]]'' approached, but ''I-177'', armed ''daihatsu'' barges, and ''[[sokotei]]s'' (armored barges armed with [[tank]] [[gun turret]]s) engaged the two PT boats and drove them off, and ''I-177'' suffered no damage.<ref name=combinedfleetI177/> After taking Adachi and Kudo and their staffs aboard, she left Sio for the last time and proceeded to  [[Madang]], New Guinea, where her passengers disembarked at around 12:00 on 11 January 1944.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She returned to Rabaul on 15 January 1944.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/>

===January–February 1944===

''I-177''′s arrival at Rabaul occurred a few days after the Japanese had decided to abandon it as a submarine base.<ref name=combinedfleetI177/> After only a brief stop, she got underway again on 15 January 1944, leaving Rabaul for the last time, calling at Truk from 18 to 20 January, and then heading for Sasebo, which she reached on 27 January 1944.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She underwent repairs at Sasebo.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/>

===North Pacific===

On 25 February 1944, ''I-177'' was assigned to the [[Northeast Area Fleet]] for operations in the [[North Pacific]].<ref name=combinedfleetI177/> After completion of her repairs, she departed Sasebo on 22 March 1944 and headed north, arriving at [[Ōminato Guard District|Ōminato]], Japan, on 25 March 1944.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She departed [[Ōminato]] on 11 April 1944 to operate in the waters off the [[Aleutian Islands]], then returned to Ōminato on 27 May 1944.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> She again put to sea from Ōminato on 8 June 1944 to conduct a war patrol in the North Pacific east of the [[Kuril Islands]].<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> It was uneventful, and after making an overnight stop at Ōminato from 22 to 23 June 1944, she headed for Yokosuka, where she arrived on 25 June 1944 and began repairs.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> When Submarine Division 22 was disbanded on 10 August 1944, she was reassigned to Submarine Division 34.<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/>

===Palau Islands campaign===

The [[Battle of Peleliu]] and [[Battle of Angaur]] began in the [[Palau Islands]] on 15 September 1944 when [[United States Marine Corps]] forces landed on [[Peleliu]] and [[United States Army]] forces on [[Angaur]].<ref name=combinedfleetI177/> On 19 September 1944, ''I-177'' departed Kure, Japan, with the commander of Submarine Division 34 embarked to conduct a war patrol off the Palaus, off [[Halmahera]] in the Japanese-occupied [[Netherlands East Indies]], and off [[Mindanao]] in the [[Philippine Islands]].<ref name=ijnsubsiteI177/><ref name=combinedfleetI177/> When she arrived in her patrol area off the Palaus on 24 September 1944, she received orders to reconnoiter [[Ulithi Atoll]] in the [[Caroline Islands]].<ref name=combinedfleetI177/>

===Loss===

''I-177'' had completed her reconnaissance of Ulithi and was on the surface returning to her patrol area off the Palaus when a U.S. Navy [[Martin PBM Mariner|PBM Mariner]] [[flying boat]] of [[VPB-16|Patrol Bomber Squadron 16 (VPB-16)]] detected her on radar on the evening of 1 October 1944.<ref name=combinedfleetI177/> As the aircraft approached, ''I-177'' [[Crash dive|crash-dived]], but not before the Mariner′s crew identified her as a Japanese submarine.<ref name=combinedfleetI177/> The Mariner dropped a [[Mark 24 mine|Mark 24 FIDO]] [[acoustic homing]] torpedo which inflicted heavy damage on ''I-177''.<ref name=combinedfleetI177/> The Mariner then passed ''I-177''′s position to a nearby [[Hunter-killer Group|hunter-killer group]] centered around the [[Escort carrier|escort aircraft carrier]] {{USS|Hoggatt Bay|CVE-75}}, which began a search for ''I-177''.<ref name=combinedfleetI177/>

''Hoggatt Bay'' was north-northeast of Angaur at 03:11 on 3 October 1944 when she made radar contact on ''I-177'' at a range of {{convert|20,000|yd|m|sigfig=3}}.<ref name=combinedfleetI177/> The [[destroyer escort]] {{USS|Samuel S. Miles|DE-183}} was detached from ''Hoggatt Bay''′s screen to investigate.<ref name=combinedfleetI177/> At 04:40, ''Samuel S. Miles''′s lookouts sighted ''I-177'' on the surface and she steered toward ''I-177''.<ref name=combinedfleetI177/> ''I-177'' crash-dived, but ''Samuel S. Miles'' gained sonar contact on her.<ref name=combinedfleetI177/> ''Samuel S. Miles'' fired a salvo  of 24 [[Hedgehog (weapon)|Hedgehog]] projectiles, and then a second salvo that sank ''I-177'' at {{coord|07|48|N|133|28|E|name=''I-177''}} with the loss of all 101 men on board, about {{convert|12|nmi}} from where the PBM attacked her.<ref name=combinedfleetI177/>

On 4 October 1944, the Japanese transmitted an order to ''I-177'' to return after completing her reconnaissance of Ulithi Atoll, but she never acknowledged the order.<ref name=combinedfleetI177/> On 18 November 1944, the Imperial Japanese Navy declared her to be presumed lost with all hands in the Palaus area.<ref name=combinedfleetI177/> The Japanese removed her from the [[navy list]] on 1 March 1945.<ref name=combinedfleetI177/>

==References==
===Footnotes===
{{reflist}}
===Bibliography===
* {{cite book|last=Edwards |first=Bernard |title=Blood and Bushido: Japanese Atrocities at Sea 1941–1945 |year=1997 |publisher=Brick Tower Press |location=New York |isbn=1-883283-18-3}}

==Further reading==
* Combinedfleet.com [http://www.combinedfleet.com/I-177.htm I-177: Tabular Record of Movement]
* {{cite book |last=Dennis |first=Peter |first2=Jeffrey |last2=Grey |author-link2=Jeffrey Grey |year=2009 |title=The Oxford Companion to Australian Military History |publisher=Oxford University Press |location=Melbourne |isbn=978-0-19-551784-2 }}
* {{cite book |last=Jenkins |first=David |title=Battle Surface! Japan's Submarine War Against Australia 1942–44 |year=1992 |publisher=Random House Australia |location=Milsons Point, NSW |isbn=0-09-182638-1 |oclc=0091826381}}

{{Kaidai type submarine}}
{{May 1943 shipwrecks}}
{{October 1944 shipwrecks}}

{{DEFAULTSORT:I-177}}
[[Category:Type KD7 submarines]]
[[Category:Kaidai-class submarines]]
[[Category:Ships built by Kawasaki Heavy Industries]]
[[Category:1941 ships]]
[[Category:World War II submarines of Japan]]
[[Category:Japanese submarines lost during World War II]]
[[Category:Submarines sunk by United States warships]]
[[Category:Warships lost in combat with all hands]]
[[Category:Submarines lost with all hands]]
[[Category:World War II shipwrecks in the Pacific Ocean]]
[[Category:Maritime incidents in May 1943]]
[[Category:Maritime incidents in October 1944]]
[[Category:Japanese war crimes]]