(Kaichu type submarine scanned from "Submarines of the Imperial Japanese Navy" by Polmar and Carpenter)

IJN Submarine RO-41:
Tabular Record of Movement

© 2001-2016 Bob Hackett & Sander Kingsepp
Revision 4

6 October 1942:
Kobe. Laid down Mitsubishi Shipbuilding as a 960-ton type K6 submarine.

5 May 1943:
Launched and designated RO-41. As the first unit of her class, RO-41 features a different conning tower, shaped to reduce the radar incident angle. Prior to the completion she is fitted with an E27/Type 3 radar detector.

25 September 1943:
Lt (promoted LtCdr 1 November; later LtCdr) Sakamoto Kaneyoshi (61)(former CO of RO-100) is apppointed Chief Equipping Officer.

26 November 1943:
Kobe. Completed and attached to Maizuru Naval District. LtCdr Sakamoto is the Commanding Officer. Assigned to SubRon 11, Sixth Fleet, for working-up.

5 March 1944:
Reassigned to SubDiv 34, Sixth Fleet. Departs Kure for Truk.

14 March 1944:
Arrives at Truk.

17 March 1944:
Departs Truk on her first war patrol to intercept Task Group 50.10's battleships sighted by RO-42. Patrols SE of Truk.

23 March 1944:
Redirected to an area E of Jaluit.

18 April 1944:
Returning RO-41 and RO-106 and RO-115 are ordered to intercept an enemy task force that was sighted S of Truk.

19 April 1944:
RO-41 is recalled to Truk.

22 April 1944:
The CINC, Central Pacific Area Fleet, Vice Admiral (Admiral, posthumously) Nagumo Chuichi (36)(former CO of YAMASHIRO), requests the CINC, Sixth Fleet, Vice Admiral (Admiral, posthumously) Takagi Takeo (39)(former CO of MUTSU) to deploy a number of submarines to Hollandia, New Guinea area to carry out attacks on Allied supply convoys.

23 April 1944:
Departs Truk to patrol N of Hollandia, New Guinea on her second war patrol.

26 April 1944:
Redirected to the Mereyon area to intercept an enemy task force. Reassigned to Submarine Group "B".

2 May 1944:
Departs the patrol area for Saipan.

7 May 1944:
Arrives at Saipan.

10 May 1944:
Departs Saipan for Truk.

13 May 1944:
Arrives at Truk.

22 May 1944:
RO-41 is due to make a supply run to Kusaie, leaving Truk at 1300 on 24th and arriving at 1630 on 28th. USS EATON (DD-510) from Majuro is dispatched to intercept the submarine, later joined by destroyer escorts GREINER (DE-37) and SANDERS (DE-40).

24 May 1944:
Departs Truk on a supply run to Kusaie (now Kosrae), Caroline Islands, carrying 12 tons of rice.

30 May 1944:
In the morning, RO-41 arrives S of Kusaie and heads for the Utwa harbor. She surfaces after sunset and contacts the local garrison. Soon thereafter, an American destroyer and two patrol boats arrive, but the submarine remains unnoticed. After a patrol plane is sighted, the approach aborted.

After 1700 (JST), when the enemy vessels have departed, RO-41 enters the anchorage. Fifteen minutes later, the same vessels appear again but again fail to spot the submarine.

31 May 1944:
RO-41's cargo is unloaded during a lull between several patrol flights. Based on his observations, LtCdr Sakamoto reports to the Sixth Fleet HQ that the enemy must have access to the current naval code. As an ad hoc countermeasure, the amount of traffic between the beleaguered island garrisons and supply boats is drastically reduced. The incoming I-5 is redirected to Ponape.

1 June 1944:
Departs Kusaie to proceed to her assigned position 10 nms W of Jaluit.

2 June 1944:
Rear Admiral Yano Hideo (43)(former CO of NAGATO), Chief of Staff of the Central Pacific Area Fleet, informs the garrison of Kusaie and various other authorities that there is reason to believe that their current ciphers are read by the Allies. As an ad hoc countermeasure, the amount of radio traffic between the beleaguered island garrisons and the supply boats is drastically reduced.

6 June 1944:
Destroyer escort USS STEELE (DE-8) arrives off Kusaie in another belated attempt to intercept RO-41.

12 June 1944:
W of Jaluit. RO-41's sound operator picks up the screw noises of an enemy convoy.

13 June 1944: Operation "A-GO" - The Defense of the Marianas:
Admiral Toyoda Soemu, (33)(former CO of HYUGA), CINC, Combined Fleet, activates the A-GO plan and orders Vice Admiral Takagi Takeo (former CO of MUTSU), CINC, Sixth Fleet (Submarines) to redeploy his boats to the Marianas. From his headquarters on Saipan, Takagi orders all available submarines, including RO-41, to the E of the Marianas.

15 June 1944: American Operation "FORAGER"- The Invasion of Saipan:
Vice Admiral (later Admiral) Richmond K. Turner's (USNA ’08) Task Force 52 lands Marine Lt Gen Holland M. Smith's V Amphibious Corps and the invasion begins. Communications with Takagi's Sixth Fleet are disrupted by the invasion. Command of the Sixth Fleet's submarines passes to ComSubRon 7, Rear Admiral Owada Noboru (44) (former CO of YAMASHIRO), at Truk.

16 June 1944:
Owada orders RO-41 and most of the Sixth Fleet's submarines to withdraw from the Marianas area.

22 June 1944:
RO-41 is ordered to return to the Western part of the Inland Sea where she is to be provisioned and repaired by submarine tender TSUKUSHI MARU.

4 July 1944:
Arrives at the Western part of the Inland Sea. Departs that same day.

5 July 1944:
Arrives at Sasebo and departs that same day for Kure for repairs and overhaul. Lt Shiizuka Mitsuo (66)(former CO of RO-500) is appointed CO. Probably at that time Type 22 surface-search and Type 13 air-search radars are installed.

15 September 1944: American Operation "STALEMATE II" - The Invasion of the Palaus:
Admiral (later Fleet Admiral) William F. Halsey's (USNA '04) Third Fleet lands the First Marine Division on Peleliu and the Army's 81st Division on Anguar Island.

18 September 1944:
Departs Kure to patrol in the Palaus E of the Philippines on her third war patrol.

24 September 1944:
RO-41 is ordered to proceed to Morotai area.

3 October 1944:
35 miles E of Morotai. At 0807, RO-41 attacks Task Group 77.1.2 (USS ST. LO (CVE-63) and FANSHAW BAY (CVE-70). Lt Shiizuka fires all four of his remaining torpedoes on what he takes to be three carriers. He hears four explosions. Actually, his torpedoes miss the two carriers, but one hits a screen escort, LtCdr L.G. Salomon's USS SHELTON (DE-407) in the stern. Shiizuka reports one CV sunk and one CV damaged.

Another escort, RICHARD M. ROWELL (DE-403) counterattacks RO-41 unsuccessfully with depth charges. ROWELL then takes off SHELTON's crew.

In one of the war's many "friendly-fire" tragedies, one of ST. LO's aircraft bombs and then dye marks a submarine's location. ROWELL attacks and sinks the submarine with a barrage of Mark 10 "hedgehog" projector charges. Later, it becomes clear that the submarine was not Japanese, but rather LtCdr A. M. Bontier's USS SEAWOLF (SS-197). SHELTON, while under tow, capsizes and also sinks at 02-32N, 129-13E.

10 October 1944:
SE of Okinawa. In the afternoon, two Yokosuka D4Y "Suisei" (Judy) reconnaissance planes from Kanoya sight three carriers and two destroyers heading NE. Vice Admiral Miwa Shigeyoshi (39) diverts RO-41, RO-43 and RO-46 to intercept Task Force 38.

14 October 1944:
Returns to Kure. For awhile, Lt Shiizuka is credited with the sinking of an enemy carrier.

18 October 1944:
Reassigned to Submarine Group "B".

20 October 1944: American Operation "KING TWO" - The Invasion of Leyte, Philippines:
Admiral (later Fleet Admiral) William F. Halsey's Third Fleet of 738 ships including 18 aircraft carriers, six battleships, 17 cruisers, 64 destroyers and over 600 support ships land the Army's X Corps (24 th Infantry and 1st Cavalry Divisions) and the XXIV Corps (7th, 77th and 96th Infantry Divisions) that begins the campaign to retake Leyte.

That same day, RO-41 departs Kure for an area E of Samar on her fourth war patrol.

23 October 1944: Operation "TA" - The Reinforcement of Leyte:
Vice Admiral Mikawa Gunichi (38)(former CO of KIRISHIMA), CINC, Southwest Area Fleet, commences "TA" to provide reinforcements, supplies and munitions to the IJA's forces engaging the American invasion forces on Leyte. Between 23 October and 11 December 1944, nine major reinforcement convoys attempt the 600-mile passage from Manila to Ormoc Bay, Leyte.

27 October 1944:
E of Samar. Lt Shiizuka sights an enemy carrier screened by several destroyers.

7 November 1944:
E of Legaspi. At 0830L, Lt Shiizuka reports sound contact with an enemy task force heading west.

8 November 1944:
RO-41 is recalled to Japan.

12 November 1944:
E of Legaspi. At 0240, Lt Shiizuka reports sound contact with a convoy heading W.

18 November 1944:
Arrives at Maizuru.

24 December 1944:
Departs Tokuyama for an area NE of the Philippines on her fifth war patrol.

4 January 1945:
Arrives W of Luzon, Philippines.

9 January 1945: American Operation "MIKE ONE"- The Invasion of Luzon:
Vice Admiral (later Admiral) Thomas C. Kinkaid's (USNA ’08) Task Force 77 lands almost 175,000 men of LtGen (later Gen) Walter Krueger's Sixth Army at Lingayen Gulf under the cover of Vice Admiral (later Admiral) Jesse B. Oldendorf's (USNA ’09) TG 77.2 bombardment force and aircraft of Rear Admiral (later Vice Admiral) Calvin T. Durgin's (USNA '16) TG 77.4. The Sixth Army begins a campaign to retake Luzon from General Yamashita Tomoyuki's 14th Area Army Group.

31 January 1945:
Returns to Kure.

1 February 1945:
Lt (LtCdr, posthumously) Honda Yoshikuni (67) (former torpedo officer of I-8) is appointed CO.

7 March 1945:
Arrives at Maizuru, then departs for Kure.

10 March 1945:
Departs Kure for a supply run to Truk, but is recalled on the 13th to participate in an attempt to intercept the Task Force 58.

15 March 1945:
Returns to Kure.

16 March 1945:
Departs Kure for Saeki.

18 March 1945:
Inland Sea. RO-41 departs Saeki, followed by I-8, RO-49 and RO-56 to intercept the damaged USS FRANKLIN (CV-13) in the Okinawa area.

19 March 1945:
LtCdr Edward Ackerman's (USNA '39) USS KETE (SS-369) is assigned to gather weather data for the forthcoming invasion of Okinawa. She is ordered to depart the area, refuel at Midway and proceed to Pearl Harbor for refit. Ackerman acknowledges his orders.

20 March 1945:
S of Tokara Kaiko (Colnett Strait). KETE, steaming eastward S of Kyushu, sends in a weather report. RO-41 is in the area making her way south. [1]

22 March 1945:
320 miles E of Okinawa. Lt Honda reports sighting an enemy destroyer. It is the last message received from RO-41.

SE of Okinawa. That same day, Honda attempts to attack units of Vice Admiral (later Admiral) Marc A. Mitscher's (USNA '10)(former CO of HORNET, CV-8) fast carrier Task Force 58.

LtCdr (later Captain) V.J. Soballe's USS HAGGARD (DD-555) is acting as a picket 12 miles ahead of the formation. At 2342, a contact is detected by radar on the surface at 25,000 yards. HAGGARD and UHLMANN (DD-687) are detached to investigate. The contact disappears, but HAGGARD acquires the target by sonar and drops depth charges. Just before midnight, a submarine broaches off HAGGARD's port beam. As the destroyer's 40-mm AA rakes the submarine's conning tower, LtCdr Soballe goes hard left rudder and rams the sub's starboard side abaft the conning tower.

23 March 1945:
After midnight, the submarine - probably RO-41 - sinks by the stern with all 82 hands at 22-57N, 132-19E. [2]

HAGGARD's bow is damaged heavily in the collision and she is ordered to return to Ulithi for repairs accompanied by UHLMANN.

15 April 1945:
Presumed lost in the Okinawa area.

25 May 1945:
Removed from the Navy List.

Authors' Notes:
[1] While several Western sources credit RO-41 with the sinking of KETE, this claim remains unsubstantiated, considering RO-41 never reported such event. KETE could have been lost to an operational malfunction or, less likely, another Japanese submarine or a mine.

Author/historian Kimata Jiro suggests that KETE may have been lost in the area south of Yakushima in a minefield laid on 27 February by KOEI MARU and TOKIWA. The 1,000-mine Yakushima minefield was right on KETE's course. Some earlier sources suggest that, at the time of her last report, KETE was stationed east of the Nansei Shoto minefield, thus she could not have been mined south of Yakushima.

[2] Some early reports claim that HAGGARD sank I-371 on this date and place, but that submarine was lost a month earlier - possibly to USS LAGARTO (SS-371).

Thanks for assistance in researching the IJN officers mentioned in this TROM go to Mr. Jean-François Masson of Canada.

Thanks go to Dr. Higuchi Tatsuhiro of Japan. Special thanks go to Hans Mcilveen of the Netherlands for info on FRUMEL intercepts.

– Bob Hackett and Sander Kingsepp.

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