KD3B (I-56) class submersible (1928)

Japan 1926-46: I-56, 57, 59, 60, 61 large oceanic submarines.

The Kaidai IIIb type (海大IIIb型, Navy large type IIIb) or I-56/156-class followed the design of the KD3a with strengthened hulls. They were a further development of the Kaidai type strongly influenced by German U-Kreuzer designs, especially U-139.

I56 at berth, colorized by Irookoto JR

Development of the Kaidai III

The Kaichū Type was follow-up large-sized submarine for the IJN, inspired by large German cruiser types, which had their origin in the 1916 Civilian submarines of the Deutschland class, later reconverted as the U-151 and also the U-139 class ordered by the German naval staff later. One was shipped to Japan as war reparations (along as others) and fed the technological gaps Japanese engineers could think of in terms of fleet submarines; the primary goal assigned to that class by the IJN. The previous KD1 and KD2 types had been moderately successful, with the first planned 1919 as “first class” types that in case of war could be deployed as far Guam or Pearl Harbour, from Japan, and back, as well as collaborating with the fleets.

In the immense expanses of the Pacific, they could be posted as places no aircraft could reach. If used in blocking lines in the parth of an incoming US fleet, they could rampage it, and somewhat re-establish the balance in favor of a smaller IJN. These Japanese “U-Kreuzer” were a very interesting design for long range fleet operations, capable of both reconnaissance and fleet interdiction, with a high surface speed and heavy armament.

Previous Kaidai types had been inspired by the British K-class submarine, and the ones from the Hachi-Roku Fleet Plan (Eight-six fleet program) of Project S22 until construction was suspended to talkf all the lessons from U 139, just arrived as war prize. The Kaidai II of Project S25 was completed in May 1925 with revised powerplant and new hull shape, better top speed and became essentially a prototype for a full class (N°52-56), ultimately cancelled in 1922 under the terms of Washington Treaty. More sturies led to further design revisions and the Kaidai-III, project number S26 for the IIIa and S27 for Kaidai IIIb. these nine submarines in a nutshell had a strengthened hull for deep diving. However the new Kaidai IIIb were elongated by 40 cm to redesign the bow, otherwie, both design were pretty similar in all points

Japanese strategists planned the Kaidai III for long-range reconnaissance, taking place in a long spotting line to cacth an enemy naval force underway, way off Japanese waters. But they should b able to also attack an enemy fleet in a war of attrition. These tactics were not new: They had been pioneered already with the Kaiserliches Marine as a way to reduced the main body of the Grand Fleet before a major engagement. Albeit the latter part of the first world war showed that undoubtely war on trade was a better strategy than trying to catch warhsips, the IJN staff, just like the USB staff, rather still believed the primary role of submarines was to prey on enemy warships. This was especially true for the IJN, in numerical inferiority since the Washington Treaty and lacking the budget to catch up anyway. It has half the number of battleships compared to the USN for example, and they had been designated as prime target for long range IJN subs. The I-51 and I-52 (KD-1 and 2) ordered under the Eight-six fleet program as prototypes, were too advanced to be revised when on 20 June 1919 after difficult negociations with former entente powers*, Japan obtained as war reparation seven German U-boats. They no only led to a complete redesign of I-52, but for the next KD-3, after the KD-2 has been cancelled, Project S-26 was born.

Final variant Kaidai IIIb

Japanese authorities wanted to reverse engineer designs the right way, and took a step further: They quickly hired hundreds of German submarine engineers, technicians, and former U-boat officers. All of them, unemployed after the defeat and probably seduced by a good salary in an exotic land, packed up, and they stayed there under five-year contracts. The United States Navy′s Office of Naval Intelligence (ONI) eventually learned about this through its contacts in Japan and soon estimated that some 800 German advisors were present in Japan by December 1920. This an enormous, unprecedented foreign recruitment, much larger than for aviation, also avid to learn about German engineers. The Japanese also sent delegations to postwar Germany, to purchase all avalable patents as well. Thus, the next KD-III would be more German than ever, truly Japan’s “U-Kreuzer”.

Based largely on the Kaidai Type II, they however featured a much strengthened double hull, with many other aspects influenced by one of the largest WWI German submarine and an example of a “U-Kreuzer”, U-125. The German term, this signified “Underseeboote Kreuzer” reflecting its range and powerful gun armament, some having two 152 mm (6 inches) light cruiser guns. However U-125, a 1,163 t (1,145 long tons) surfaced boat, was also preculiar. This Type EII was indeed a minelayer submarine, and had a single 15 cm deck gun. The Japanese essentially got rid of its 100 cm (39 in) stern mine chutes for 42 mines, and added two more torpedo tubes forward and two aft. But many technical details of U-125 were essentially transplanted on a modified KD-2 hull.

But for the main points of distinction again between the Kaidai IIIa and IIIb: The bow shape was refined to improve seaworthiness, making the overall length slightly longer of approximately 40 cm and slight improvements were also made to the shape of the bridge and stern. What’s more, the design measurements were all switched from the Imperial to the German metric system, that Japan followed ever since. Like the Kaidai Type 3a, they had been planned acording to the 1923 (Taisho 12) plan, with five completed between 1928 (Showa 3) and 1930 (Showa 5).

All nine boats were built total in the Kaidai III serie from 1927 and until 1930. They were the first “mass-produced” fleet submarines in Japan. I-63 sank in an accident before the start of the war, so it has no combat history. In the early stages of the Pacific War, they conducted commerce raiding, during which I-60 was sunk. The remaining three participated in the Battle of Midway in June 1942 (Showa 17) and were then converted into training submarines in Kure. I-156 and I-157 participated in a transport mission to Kiska Island during the Aleutian Islands campaign in June 1943 (Showa 18). The others were used as training submarines until the end of the war and were scuttled afterward.

Design of the KD-3b class

Hull and general design

I-56 and her sisters of the KD-IIIb displaced 1,829 metric tons (1,800 long tons) surfaced, 2,337 metric tons (2,300 long tons) submerged, with around 2,300 tons fully loaded and submerged. They were larger than the war prize U-125, larger than I-51 and 52 as well but similar to the KD-IIIa. They reached 101 meters (331 ft 4 in) long (so indeed longer than the KD-IIIa) for the same beam of 8 meters (26 ft 3 in), but higher draft at 4.90 meters (16 ft 10 in) for a complement of 60 officers and crewmen.

The hull was still close to the one on I-52 but with differences increased thickness for the inner hull. Thus enabled a diving depth of 60 metres (197 ft), probably around 100m for the crushing limit. Engineers also managed to have the internal volume slightly increased with a cross section reshaped as slightly trapezoidal, adding a burden of 300 tons displacement however. They had the same anti-submarine net cutter at the bow and O-ring for towing, but its shape was refined and even more “pointy” like the U139. The forward section was fuller for extra buoyancy, but sloped downwards to the slanted stem. The two anchors were in recesses forward for better flow, with two foward diving forward planes aft of the anchors in the same horizontal recesses. The main gun was the same as previous models (see below), fitted in a breawater platform sponsoned over the sides to reduced seawater spray.

The conning tower was roughly similar, but integrated a well profiled “foot” at its base. There was the same enclosed helmsman post with windows forward, and the open navigation platform further aft and up. The boat had three periscopes, two for watch and one for attack. The aft section of the conning tower was open and AA guns were located there. It ended with a signal mast. There was another small mast aft at the end of the deck, flying the national colors. The exhausts were located there too. The upper rudder aft was protected by a guard bar.

Powerplant

I59 on trials, colorized by Irookoto JR

I-56 and sisters had however Kampon diesels, derived from the Sulzer diesels. They had slightly improved performance over the ones on I-52. When surfaced, these two 3,400-brake-horsepower (2,535 kW) diesel engines drove two fixed-pitch 3-bladed propeller shaft, for 6,800 bhp (5,100 kW) (diesels) total. When submerged, the propeller were disconnected and reconnected to the shafts coming from a pair of 900-horsepower (671 kW) electric motors for 1,800 hp total (1,300 kW). Thanks to this, top speed while surfaced reached 20 knots (37 km/h; 23 mph) surfaced, and 8 knots (15 km/h; 9.2 mph) submerged. The surface range was 10,000 nautical miles (19,000 km; 12,000 mi) at 10 knots (19 km/h; 12 mph) and the submerged range was 90 nmi (170 km; 100 mi) at 3 knots (5.6 km/h; 3.5 mph). Other sources precises she could also do 6,130 nautical miles (11,400 km) at 16 knots surfaced if needed.

Armament

I-56 and sisters of the KD-3b class retained the same armament as the previous KD-2, eight 533mm torpedo tubes, six forward, two aft (16 total), a 120mm/45 (4.7″) dual-purpose gun thanks to the mount and recess for extra elevation initially. Later AA guns were installed.

120cm/45 Type 10 deck gun

This 12 cm/45 10th Year Type or 120/45 10-shiki, naval gun was installed. Initially this was a dual purpose anti-aircraft and coastal defense gun, derived from the 12 cm/45 3rd Year Type naval gun. It was relatively simple to produce, threw a powerful shell and did not require external power. It was also used on three cruiser classes and the Taiyō-class escort carrier.

Specs

Mass: 8.5 tons, length 5.94 m (19 ft 6 in), barrel 5.4 m (17 ft 9 in) L/45. 2.16 m (7 ft 1 in) x 2.34 m (7 ft 8 in).
Shell: Fixed QF 120×708mmR 20.6 kg (45 lb 7 oz). Semi-automatic with horizontal sliding-wedge breech, hydro-spring recoil.
Pedestal mount, rate of fire 10-12 rpm, mv 825 m/s (2,710 ft/s) range 16,000 m (17,000 yd).

Type 6 533mm Torpedo

The KD-3b type type had six tubes in the bow and reloads for each, plus two in the stern and two reloads, like the previous I-55, for sixteen total of the 6th Year Type torpedoes, the first type using metric measurements. This model was designed at the brand new Imperial Japanese Navy Technical Department, favoring a rule era naming scheme. Development started in 1914, completed in 1917 for a service in 1918 on both surface ships and submarines. Originally defined in the Eight-Eight Program replacing the 18-in by a 21-inch caliber torpedo and planning a 61 cm (24-inch) Type 8. This went with the decision to switch to metric units. In 1922, the Washington Naval Treaty was signed by Japan and forbade any caliber besides 550 mm (French standard) and the international norm remained at 53 cm.

The 1,432 kg (3,157 lb), 6.84 m (22.4 ft) Type 6 was powered by a Wet heater to bring its 203 kg (448 lb) Shimose warhead at 7,650 m (4.13 nmi) at 36 knots (67 km/h) ot 10,000 m (5.4 nmi) at 32 knots (59 km/h), 15,000 m (8.1 nmi) at 26 knots (48 km/h). These were above average performances already compared to other Navies for that caliber. It’s possible they tested the Type 89 in the 1930s, however the latter was only carried by the Junsen and Kaidai-type submarines. They could reach 45 knots. They could also have tested or deployed the Type 92 electric torpedo, leaving no trail (more data on later posts).

Type 3 machine gun

Japan acquired a license and began producing Hotchkiss Mle 1897 machine guns in 6.5mm Arisaka, 87 caliber. During the Russo-Japanese War, each Japanese division had 24 Hotchkiss machine guns. Being lighter than the Russian Maxims, the Hotchkiss performed well. The production evolved to become the Type 3 Heavy Machine Gun in 1914. However it seems they were only present on the KD-3b, not the KD-3a.

I-53 and following could optionally carry sixteen naval mines of the type compatible with her tubes. This also is not confirmed by all sources. More on Navweaps.

Sensors

These submersibles had a pair of hydrophones, K-Chubu type echo-sounder, possibly from the start. Other equipments included a ratio transmitter special 4 and 2 receiver RDF-T4. They also had degaussing equipment with three 3/8 inch coils directly below deck and two fitted on the sail like her sister.

⚙ I-56 specifications
Displacement	1,829 long tons surfaced, 2,330 tons submerged
Dimensions	101 x 8 x 4.82m (328 ft 1 in x 26 ft 3 in x 15 ft 10 in)
Propulsion	2x Kampon diesels: 6,800 bhp surfaced. 2 EM, 1,800 shp submerged
Speed	20 knots surfaced (37 kph), 8 knots (15 kph) submerged
Range	c190 tons fuel, 10,000 nm/10 kts surfaced, 90 nm/3 kts submerged
Armament	8× 533 mm TTs (6 bow, 2 stern, 16), 1x 120 mm/45 deck gun, see notes.
Test depth	60 m (197 ft)
Sensors	K type Hydrophones
Crew	60

Career of the KD-IIIb class

I-56 (1928)

I-56
I-156 (ex-I-56) was the leading Kaidai IIIb, ordered from Kure Naval Arsenal on 3 November 1926, launched on 23 March 1928 and commissioned on 31 March 1929. She was attached to the Kure Naval District. On 1 April 1929, she was assigned to Submarine Division 19 (hence her hull id), assigned to Submarine Squadron 2, 2nd Fleet, Combined Fleet. It could have been from 1 April 1929 or 30 November. On 1 December 1931 she joined the the Kure Guard Squadron and district. On 20 May 1932, SubDuv19 was reassigned to SubRon 2, 2nd Fleet. I-56 left Sasebo on 29 June 1933 with her sisters I-53, I-54 and I-55 and SubDiv 19′s I-57 and I-58 for a training cruise off China and Mako, Pescadores, then Takao (Formosa/Taiwan) on 5 July, departed on 13 July for more Chinese waters frills and back to Tokyo Bay on 21 August. 4 days later she took part in a fleet review at Yokohama. On 27 September 1934 she departed Ryojun in Manchukuo with I-57, I-58, I-61, I-62, I-64, I-65, I-66, and I-67 for a training cruise off Qingdao and back to Sasebo on 5 October.

Her unit went to the Kure Guard Squadron/District on 15 November. She trained with the Combined Fleet on 15 November 1935, SubRon 1 1st Fleet and on 1 February 1936 had naval maneuvers off Honshu. She had a collision with I-53, 32 nm (59 km; 37 mi) SE of the Daiosaki lighthouse at 10:16 on 27 February while in poor visibility but damage was light. on 18 December 1935 a sudden gale had I-56’s own boat, as she was anchored in Kure capsizing at 06:50 with the loss of her CO and four engineers. After sunrise, a single survivor was rescued. Kure Naval District was disbanded on 7 January 1937, she was decommissioned and on 1 December 1937 recommissioned, resuling activity on 1 January 1938. She was placed in the 3rd Reserve, Kure Naval District, on 15 December 1938. She was reactivated on 15 November 1939, with SubDiv 19 reassigned to SubRon 4, 1st Fleet. On 15 November 1940, she was reassigned directly to the Combined Fleet.

I-56 departed Kure on 20 November 1941 for Samah, China′s Hainan Island, arrived on 26 November. She departed on 1 December and ordered to support Operation E, invasion of British Malaya, arriving northwest of the Anambas Islands. On 8 December she spotted, fired, but missed the Royal Netherlands Navy submarine HNLMS K XVII (probable) east of the Peninsula. On 11 December, she attacked the Norwegian 1,186 GRT merchant ship Hai Tung underway from Bangkok to Singapore with gunfire. On 14 December the Dutch submarine HNLMS K XII detected faint propeller noises, surfaced to presicope depth and at 11:00 sighted a periscope to starboard. She steered to ram her, now down to 100 meters (109 yd), but was detected, broke contact and zigzagged away. I-56 arrived at Cam Ranh Bay on 20 December, resupplied and departed on 28 December for her second war patrol, to the Indian Ocean, southwest of Tjilatjap (Java).

On 4 January 1942 she sank the 2,626 GRT British cargo ship Kwangtung with gunfire and is reported to have rammed one of her lifeboats, machine-gunned others. Only 35 survived. On 5 January, she surfaced and fired at the Dutch 8,169 GRT APC Tanimbar 40 nautical miles southeast of Tjilatjap, damaging her but abandoning the attack as she returned a vigorous fire herself. While underwater, 80 nm or 150 km southwest of Tjilatjap, she detected, approached ad launch torpedoes, then hit the Dutch 3,032 GRT steamer SS Van Ress underway to Emmahaven, Sumatra. Her engine room wa sblasted open on 8 January 1942, killing 6; she listed to port and sank. I-56 surfaced and her CO questioned survivors about her cargo and destination. At 21:00, I-56 sank the Dutch 2,263 GRT passenger ship Van Riebeeck with gunfire, killing 13 of her crew. The remainder were recsued by the minelayer HNLMS Willem van der Zaan.

While off Bali on 12 January 1942, she torpedoed the Dutch 2,065 GRT merchant ship Patras, underway to Tandjong Priok, Batavia; but her spotters saw the trail and she evaded the torpedo. So I-56 surfaced and opened gunfire, while the steamer made her max 13 knots, taking several hits in her stern, caught fire. A KNIL Dornier Do 24K arrived on the scene, I-56 dived to avoid attack. However I-56 later surfaced and resumed attack on Patras, until she reached safety in Banjoewangi, Java. I-56 returned to Cam Ranh Bay on 18 January 1942. For her 3rd war patrol in “A Group” on 31 January 1942, she left Cam Ranh Bay for a new patrol area in the Indian Ocean, Sunda Strait (Java-Sumatra). After refueling in the Anambas Islands, she arrived on 2 February 1942 and 2 days later, attacked the Dutch 979 GRT merchant ship Togian as part of Convoy JS.1 with gunfire. Togian survived, but later was scuttled at Koepang. On 11 February she reported an attack on an Allied merchant ship at the southern entrance of the strait. She then arrived at Staring Bay, Celebes on 21 February to resupply. Her 4th patrol started on 5 March. I-56 was sent again off Tjilatjap. On 9 March, she sported a lifeboat Scorpion carrying 12 Allied airmen from Tjilitjap, underway for Roebourne in Western Australia. I-56 surfaced, her CO observed the boat but did not arrest them. They could resume their trip.

However SubRon 4 was disbanded so by 10 March 1942, her unit was reassigned to SubRon 5. Her patorl ended on 12 March 1942 in Staring Bay but instead of another patrol she sailed for Kure, arrived on 20 March 1942 for maintenance, and on 14 May was ordered to Kwajalein under the new pennant I-156, arrived on 24 May. Two days later she departed for a 5th war patrol, in support of Operation MI, the planned attack on Midway. SubRon 5 was assigned to the Advance Expeditionary Force. She was sent in a line with I-157, I-158, I-159, I-162, I-165, and I-166 to intercept and spot possible USN reinforcements. But the defeat on 4 June led 6th Fleet CIC Vice Admiral Teruhisa Komatsu, to ordered her westward. Admiral Isoroku Yamamoto then ordered Komatsu to interpose the submarines between the retreating Japanese and USN carriers. I-156 veered north-northwest at 3 knots by day, 14 knots after dark to save fuel. At 04:00 on 5 June she spoptted the oiler USS Guadalupe (AO-32) escorted by two destroyers, 550 nm (1,020 km; 630 mi) east of Midway but hhd no firing position. Only I-168 had more luck. She was back to Kwajalein on 20 June. On 22 June she departed for Kure, Japan, reached on 30 June for maintenance and crew R&R. On 10 July 1942, SubRon 5 was disbanded, SubDiv 19, assigned to the Kure Submarine School.

Her career resumed however by 21 May 1943. She was sent to evcuate the garrison at Kiska, Aleutian Islands. She was attached temporarily to SubRon 1 (I-2, I-7, I-21, I-24, I-34, I-36, I-155, I-157, I-168, I-169, and I-171) for this operations, departed on 22 May via Yokosuka, Paramushiro and entered the Northern District Force, 5th Fleet, on 29 May. After refueling from the oiler Teiyō Maru on 2 June she proceeded for a supply run to Kiska with ammunition and food, arrived on 15 June but submerge due to an Allied air raid. She embarked 60 passengers, and returned to Paramushiro on 20 June. She departed the next day for Kure, arrived on the 26th and again attached to the local District on 28 June, later assigned to training duties until 1 April 1945, reassigned to SuDiv 34 as kaiten carrier, Modified to carry two and making three voyages from May to August to transport them from Ōzushima (Seto Inland Sea) to kaiten shore bases at Kyushu. In July 1945 her crew, along with the crews of I-157, I-158, I-159, and I-162, were trained for kaiten attacks. On 15 August she was demobilized. She departed Hirao on 25 August as part of the Shinshu-tai (“Land of Gods Unit”) kaiten group to attack Allied shipping when ordered cancelled and recalled and she surrendered to the Allies on 2 September. Stricken on 30 November she was sent to Sasebo, stripped and on 1 April 1946 towed by USS Nereus (AS-17) from Sasebo to the Gotō Islands, to be scuttled with explosive charges as part of Operation Road’s End.

I-57 (1928)

I-57
Built by the Kure Naval Arsenal, I-57 was laid down on 8 July 192, launched on 1 October 1928, completed, then commissioned on 24 December 1929, attached to the Kure Naval District at first, then SubDiv 19, SubRon 2, 2nd Fleet, Combined Fleet like her sisters. The unit history was also her history (see above). Placed in reserve at Kure from 15 November 1930, reactivated on 14 November 1931 she was rertained in the Kure Defense Division but by 20 May 1932, she was reassigned to SubRon 2, 2nd Fleet until June 1932 and back on 5 October 1932. Next she had a training cruise off China and Mako via Takao. She took part in the 1933 fleet review at Yokohama. On 27 September 1934, I-57 departed Ryojun in Manchukuo for another cruise at Qingdao, and back to Sasebo on 5 October 1934, reserve at Kure from the 22th, then Kure Guard Squadron, reactivated on 15 November 1935, for SubRon 1/1st Fleet. 1 December 1936 saw her back at the Kure Naval District, 1st Reserve from 7 January 1937, reactivated on 1 January 1938, but 3rd Reserve from 15 December. Reactivated from August 1939 she joined SubRon 4, 1st Fleet from 15 November. On 20 November 1941 she left Kure bound for Samah, Hainan Island and was tasked to support Operation E (Malaya) in the South China Sea. On 8 December she was part of a patrol line off Trengganu, uneventful so she ended at Cam Ranh Bay on 20 December.

She started her second patrol on 28 December in the Java Sea and off Surabaya. At 16:30 on 7 January 1942, she spotted, surfaced and gunned down southeast of Kangean Island the Dutch 3,077 GRT auxiliary tanker Tan-3 underway to Surabaya and she sank. She was back on 16 January. Before her 3rd patrol she was immobilized after an outbreak of dysentery on 7 February and could only departed on 1 March for Staring Bay, Celebes. SubRon 4 was disbanded on 10 March so she was reassigned to SubRon 5. I-57 departed on 13 March for Kure, arrived on 20 March for maintenance, and the for Kure, on 14 May, and from there, was ordered to the Kwajalein Atoll, renumbered I-157 and on 26 May departed for Operation MI (invasion of Midway) as part of the Advance Expeditionary Force, forming a patrol line, later moved westward after the defeat. But she never spotted the USS carriers, eve after the line was moved again north-northwest. She was back to Kwajalein on 19 June. On the 22th June she left for Kure, arrived on the 30th when SubRon 5 was disbanded, SubDiv 19 reassigned to the Kure Naval District as training ship until May 1943.

Like her sisters on the 21st it was decided she would take part in the evacuation of Kiska, Aleutian, attached to the Northern District Force, 5th Fleet. From Yokosuka, she gained Paramushiro, refueled and sailed to Kiska with food and ammunition but on 16 June 1943 in fog, she ran hard aground near Amchitka. Her crew dumped diesel fuel, lubricating oil, torpedoes, even some battery cells, and she eventually was refloated, but with such damage the mission was aborted and she could not dive so she sailed back to Paramushiro on 20 June, refulled from Teiyo Maru, then back to Kure, on 26 June for repairs. On December 1943, she was repainted in an experimental camouflage pattern of dark grey with a bluish hue like U-511 purchased in 1943 as Ro-500. She remained at for Submarine School tests at Iyo Nada, Seto Inland Sea from 5 January 1944 and from mid-July 1 with Ro-49 tested the Type 13 air-search radar. From 20 April 1945, she was reassigned to SubDiv 34, 6th Fleet and from May she started conversion as a kaiten carrier and until August 1945, made three voyages at Otsushima and Kyushu. She then underwent training, and was installed a Type 3 sonar and new, modern fire-control system, still testing them on 15 August. She surrendered in September, stricken 30 November, sent to Sasebo, stripped of and towed by USS Nereus (AS-17) off the Gotō Islands to be scuttled with explosives.

I-59 (1928)

I-59
I-59 was laid down on 25 March 1927 at the Yokosuka Naval Arsenal, launched on 25 March 1929, completed and commissioned on 31 March 1930. She joined the Kure Naval District, SubDiv 28. On 1 December 1930, it was attached to SubRon 2/2nd Fleet, Combined Fleet, the SubRon 1/1st Fleet on 1 December 1932. She was at the Sasebo Defense Division from 15 November 1933 but decommissioned and placed in reserve (from December Sasebo Guard Division). Reactivated, on 15 November 1934 she returned to SubRon 2 and on 7 February 1935 she had a training cruise in the Kuril Islands, concluded at Sukumo Bay on 25 February 1935. She left Sasebo with 8 other subs on 29 March for Chinese waters, back on 4 April 1935. On 15 November she returned to SubRon 1 but was decommissioned from November 1936 until early 1937, leaving Sasebo with I-60 and I-63 on 27 March for a cruise to Qingdao, back to Ariake Bay on 6 April, then she was attached to the Sasebo Defense Squadron by December, and SubRon 1 on 15 December 1938. Until 29 January 1941, she became flagship of her division, relieved, then again from 3 December 1941. She was overhauled at Kobe, Japan on 7 December, departing on 31 December with I-60 for Davao, Mindanao, arrived on 5 January 1942 to refuel, relieved as flagship by I-60 on 9 January.

A day later she departed Davao for a first war patrol to the Banda Sea, Sunda Islands, Celebes with SubRon 5 (I-62, I-64, I-65, and I-66) to covered landings at Kema and Manado from 11 January. Later she depayed for Christmas Island. She sank the Norwegian 4,184 GRT cargo steamer Eidsvold, off Flying Fish Cove on 20 January 1942 (only the 6th torpedo hit). On 25 January, she surveyed Sabang, Sumatra and later torpedoed and sank a British merchant ship, taking her crew prisoner for interrogation, later released. She ended in Penang, Malaya, 26 January. She departed on 21 February for an area southwest of Sumatra and at 23:35, 1 March she spotted and torpedoed the Dutch 1,035 GRT passenger ship SS Rooseboom underway to Padang and Colombo. 500 British military personnel and civilians moslty died whe she capsized and sank quickly, with 135 survivors. Two were later rescued by SS Palopo and the remainder reached Sumatra 30 days later. She was back to Penang on 12 March.
On the 22th she left for Sasebo, arrived on on 1 April for refit, her division disbanded. She joined SubDiv 19 from 10 April and departed on 19 May for Kwajalein as I-159 and took part in the Battle of Midway, in a moving line (see above), back to Kwajalein on 21 June.

On 22 June she returned to Kure, and from 10 July SubRon 5 was disbanded so she was assigned to Kure Naval District for training on 18 July 1943, but later relieved as flagship. On 1 December 1943 she wa sin the Kure Submarine Squadron. On 25-26 December she was sent to Tokuyama, refueled at the Tokuyama Fuel Depot, and from January 1944 took part in the first stage of submarine camouflage pattern experiments at Iyo Nada. She had the “No. 5” camouflage scheme, greenish-gray pattern on the hull and sides of the CT. Later in January 1944, she tested the Type 2 magnetic influence exploder, for the Type 95 torpedoes. On 23-25 February 1944 she was in the second stage of the camouflage pattern experiments, No. 5 pattern on her wooden deck. Her division was disbanded on 20 April 1945 so she joined SubDiv 34, 6th Fleet and from May started conversion at Kure as kaiten carrier, transporting them to Shikoku and Kyushu until July 1945, starting active training, but allied raids forced her to Maizuru, Honshu′s east coast from August. On the 6th she was assigned to Shinshu-tai kaiten group.

She was caught on 11 August 1945 in a massive raid from Iwo Jima from P-51 Mustang. She was strafed and her main ballast tanks were pierced. She was transferred to the kaiten base at Hirao, southern Honshu after makeshift repairs and on 15 August, reassigned to SubDiv 15, 6th Fleet. Despite the Emperor’s radio call, her crews continued to prepare for the first Shinshu-tai sortie. On 16 August, she departed Hirao (only one underway), with still orders to attack Soviet shipping off Vladivostok. She passed the Seto Inland Sea, Bungo Strait and arrived off Ōsumi Strait but on 17 August 1945 off Miyazaki Prefecture, Kyushu, she received ordered from Hirao to stop, and arrived at Aburatsu, Kyushu, destroying all of her secret documents. On the 18th she sailed back to Hirao to surrender in September. She was moved to Sasebo in October, stripped off, struck on 30 November and later scuttled off the Goto Islands in Operation Road’s End, 1 April 1946.

I-60 (1928)

I-60
I-60 was built at Sasebo Naval Arsenal, keel laid on 10 October 1927, launched on 24 April 1929, completed and commissioned on 20/24 December and attached to the Sasebo Naval District, later with I-63, assigned to SubDiv 28, activated that day, at SubRon 2/2nd Fleet on 1 December 1930. On 1 December 1932, this was SubRon 1, and he continued reassignations, Sasebo Defense Division November 1933, decommissioned, then Sasebo Guard Squadron by December, SubRon 2 November 1934, recommissioned and on 7 February 1935 she had a training cruise in the Kuril Islands and in March 1935 in Chinese waters, back to Sasebo on 4 April 1935. She was in Terashima Strait with I-59 and I-63 on 22 July 1936 in fleet exercises when swamped by large waves (minor damage, starboard anchor chain and work boat gone). She was decommmissioned in 1936 but recommissioned on 1 December. On 27 March 1937, she left Sasebo with I-59 and I-63 to train off Qingdao, ended in Ariake Bay on 6 April 1937 and returned to Sasebo Defense Squadron from December, but back with SubRon 1 on 15 December 1938.

By late January 1939, she started a week of fleet exercises. Early on 2 February 1939, she sailed for her assigned station for a simulated attack and there was some confusion. I-63 arrived on station in the Bungo Strait, 60 nm NW of Mizunokojima Lighthouse, cut diesels and lights at 04:30, surfaced, and I-60, proceeded at 12 knots toward her own assigned station but by error she entered I-63′s assigned area and at 05:00 her watch officer sighted her two white lights, misidentified as fishing boats and putting her on collision course. The error was revealed when 220 yards (200 m) apart. I-63′s crew called her CO to her bridge, he realized she was about to be rammed, ordered full ahead and to close all watertight doors. I-60 nevertheless still rammed I-63, which tore open her starboard ballast tank and auxiliary machinery compartment and watered poured in so much she sank in a few minutes under 320 feet (98 m) with all 81 crewmen. I-60 suffered a crushed bow buoyancy tank and rescued the CO and six other crewmen which jumped off the CT, her only survivors. In the post-accident investigation, the court of inquiry found I-60 navigation error while having unsatisfactory lookout procedures and inadequate management. I60’s CO took full responsibility, was suspended from duty, and promotion delayed.

On 15 November 1939, SubDiv 28 was attached to the Sasebo Naval District at the submarine school at Kure, from November 1940 in SubRon 5, Combined Fleet. I-60 relieved I-59 as division flagship on 6-29 January 1941. She entered the 3rd Reserve, Sasebo on 10 April 1941 , then Tama Zosensho shipyard for refit and modernization, then as flagship again from 20 May to 3 December 1941. She was assigned to the Malaya Invasion Force, Pacific campaign and had a odernization at Tamano in December 1941. On 26 December she entered Unit B, Indian Ocean, commander, SubDiv 28 aboard. She left Kobe on 31 December with I-59 for Davao, Mindanao, arrived on on 5 January 1942 to refuel and again as flagship on 28-9 January. A day later she departed with I-59 for a war patrol to the Banda Sea and Sunda Islands, Celebes and with SubRon 5 with I-62, I-64, I-65, and I-66 they protected the landings at Kema and Manado, northern Celebes, from 11 January. Two days later she sailed out with I-59 and to the Indian Ocean, south of the Sunda Strait (Java-Sumatra) and ended in Penang, Malaya. On 16 January she reported her arrival in her patrol area (Sunda Strait) with a last report in the evening but she was never heard from her again.

As for the cause, this was HMS Jupiter, which was on 17 January 1942 in the Java Sea, 25 nm (46 km; 29 mi) NNW of Anak Krakatoa. She was escorting the troopship USS Mount Vernon (AP-22) to Aden. She received a distress signal from a nearby merchant ship under attack, was detached from Mount Vernon and started a sonar search in the area, after two hours making contact. Two depth charge attacks followed, heavily damaged, I-60 surfaced astern, so close her guns could not depress enough to open fire and the submarine on her side was scrambled her gun crew and started to engage Jupiter with her deck gun, until Jupiter changed course, took enough range to be able to fire starting with her 20 mm Ozerlikon, ideal to sweep I-60’s deck clean. I-60′s crew kept emerging to replace fallen gunners and she managed that way to land 7-8 rounds a minute. Jupiter was hit in her “A” 4.7-inch (120 mm) twin gun turret, killing the crew. Eventually the J-class destroyer fired two torpedoes at I-60 but missed, and resumed fire with her remaining four 4.7-inch (120 mm). I-60 took on a list but in her CT, her 7.7 mm crew continued to fire. Jupiter silenced the CT with 20 mm fire. Then she pierced her CT with a 4.7-inch (120 mm) round close to the stern, causing an internal explosion. Flame emerged from the CT. She passed 15 feet (4.6 m) abeam and dropped a single depth charge at 0 setup. This casued a second detonation which ruptured her pressure hull and she sank by the stern at great depht at the southern entrance to the Sunda Strait leaving three survivors. She was struck on 10 March 1942.

I-61 (1928)

I-61
She was both a boat from the KD3b and the first unit of the KD4 sub-class, built by Mitsubishi NyD, Kobe, keel laid on 15 November 1926, launched on 12 November 1927, completed on 6 April 1929 and assigned to the Sasebo Naval District. On 24 April 1929 she departed with I-62 to form SubDiv 29, SubRon 1/1st Fleet from 1 December 1930. I-61 was decommissioned, placed in reserve on 11 January 1932, then transferred to the Sasebo Defense Division/District on 10 November and SubRon 2 from 15 November 1933, recommissioned on 1 June 1934. On 27 September she left Ryojun in Manchukuo for Qingdao, training there with nine other submarines before heading back to Sasebo on 5 October 1934. On 7 February 1935, she departed for a cruise to the Kuril Islands and back at Sukumo Bay on 25 February 1935. Then from 29 March 1935 to Chinese waters, back to Sasebo on 4 April 1935. On 15 November 1935, the division returned to the Sasebo Defense Squadron and on December 1936, SubRon 2 again, and the Submarine School at Kure. On 11 March 1939, she had a collision with the Japanese destroyer Yakaze off Mitajiri. She later was decommissioned, transferred to the 3rd Reserve, Sasebo Naval District, reactivated on 15 November 1939 and decomm. on 20 March 1940.

She was recommissioned either on 15 April or 15 November 1940 as par tof SubRon 5, Combined Fleet. On 8 January 1941, she collided with the gunboat Kōshū Maru, south of Cape Ashizuki. On 2 October 1941, she carried the commander of SubDiv 29 from Sasebo, with the tender Rio de Janeiro Maru and eached Murokusumi, Yamaguchi Prefecture, Koshiki Channel. Kiso Maru saw I-61 aft of Rio de Janeiro Maru, misjudged her passing distance and collided with I-61 at 23:21. I-61 sank with the loss of all 71 men, but she was refloated on 20 January 1942 but given her state, sold for scrapping after being struck on 1 April 1942.