(KS type RO-109 scanned from "Submarines of the Imperial Japanese Navy" by Polmar and Carpenter)

IJN Submarine RO-106:
Tabular Record of Movement

2001-2012 Bob Hackett & Sander Kingsepp

Revision 3

17 December 1941:
Kure. Laid down at Kure Navy Yard as a 525-ton (standard) Kaisho (KS) Type submarine No. 216.

8 April 1942:
Submarine No. 216, under construction, is designated RO-106 and attached to the Sasebo Naval District.

30 May 1942:

26 December 1942:
Completed, registered in the IJN and assigned to the Kure SubRon. Lt Saeki Takuo (59)(former CO of I-157) is the Commanding Officer.

15 February 1943:
While navigating the Hayase Seto channel off Kure, RO-106's rudder is jammed and she runs aground. She is towed to Kure for hull repairs. 15 March 1943:
Reassigned to Rear Admiral (later Vice Admiral) Harada Kaku's (former CO of CVS CHIYODA) SubRon 7 in Vice Admiral, the Baron, Samejima Tomoshige's (former CO of NAGATO) Eighth Fleet/Southeast Area Fleet based at Rabaul.

31 March 1943:
Departs Sasebo for Rabaul.

12 April 1943:
Arrives at Rabaul.

22 April 1943:
Departs Rabaul on her first war patrol SE of Guadalcanal.

1 May 1943:
Lt Saeki is promoted LtCdr.

14 May 1943:
Returns to Rabaul.

27 May 1943:
Departs Rabaul for her second war patrol, but has to abort the mission because of diesel engine troubles.

29 May 1943:
Returns to Rabaul.

31 May 1943:
Departs Rabaul on her third war patrol SE of Guadalcanal.

12 June 1943:
Lt Nakamura Motoo (62)(former CO of RO-31) is assigned as the next Commanding Officer.

16 June 1943:
Returns to Rabaul.

30 June 1943: American Operation Operation "TOENAILS" - The Invasion of New Georgia:
Rear Admiral (later Admiral) Richmond K. Turner's Third Fleet Amphibious Force, supported by land-based aircraft, lands Marines and Army troops on Rendova and other islands in the New Georgia area, Solomons.

That day, RO-106 departs Rabaul on her fourth war patrol to patrol off Rendova.

18 July 1943:
Blanche Channel, off New Georgia, Solomons. RO-106 torpedoes and sinks 1,625-ton LST-342 (Landing Ship Tank) at 09-03S, 158-11E. [1]

21 July 1943:
Returns to Rabaul.

31 July 1943:
Departs Rabaul for her fifth war patrol.

20 August 1943:
Returns to Rabaul. Reassigned to the new SubDiv 51 with RO-100, RO-101, RO-103, RO-104 and RO-105 (F).

1 September 1943:
Departs Rabaul for her sixth war patrol in San Cristobal area.

22 September 1943:
Redirected to rescue IJNAF pilots downed in air battles two days earlier.

24 September 1943:
Returns to Rabaul.

6 October 1943:
Departs Rabaul for a supply run to Sarmi, New Guinea.

7 October 1943:
Arrives at Sarmi, unloads her cargo, then departs.

9 October 1943:
Redirected to the area E of Lae.

19 October 1943:
RO-106 is detected by aircraft and chased by several vessels that drop depth-charges. She receives serious damage and has to abort her patrol. [2]

23 October 1943:
Returns to Rabaul.

27 October 1943:
Departs Rabaul for Sasebo for battle damage repairs.

8 November 1943:
Arrives at Sasebo.

16 December 1943:
Departs Sasebo.

29 December 1943:
Arrives at Rabaul.

31 January - 8 February 1944: American Operation "FLINTLOCK" - The Invasion of the Marshall Islands:
Task Force 58 lands the 4th Marine Division and the Army's 7th Infantry Division that capture the Kwajalein, Roi-Namur and Majuro atolls.

1 February 1944:
Departs Rabaul for her second supply run to Sarmi.

3 February 1944:
Arrives at Sarmi, unloads her cargo, then departs.

5 February 1944:
Returns to Rabaul.

10 February 1944:
Departs Rabaul for her third supply run to Sarmi.

12 February 1944:
Arrives at Sarmi, unloads her cargo, then departs.

14 February 1944:
Returns to Rabaul.

18-21 February 1944: American Operation "CATCHPOLE" - The Invasion of Eniwetok:
The V Amphibious Corps Reserve (22nd Marine Regiment and the Army's 106th Infantry Regiment) capture Engebi Island, Eniwetok and Parry atolls.

19 February 1944:
At 1712 that day, FRUMEL intercepts and decrypts the following message from an unidentified originator: "Amend areas as follows:I-42 on 120 mile radius in sector 050 to 090 degrees from Natsushima.RO-106 on 90 mile radius in same sector."

Reassigned to the 1st Advance Submarine Unit. Departs Rabaul on her eighth war patrol to intercept an enemy task force in the Truk area.

1 March 1944:
Redirected to Brown Island, Eniwetok.

4 March 1944:
Makes a periscopic reconnaissance of Brown Island. Fails to spot any targets.

5 March 1944:
During the next periscopic reconnaissance, RO-106 spots several cruisers, destroyers and a repair ship. Three days later, Mitsubishi G4M Betty bombers of the 705th Naval Air Group (NAG) from Truk attempt to bomb the targets located by the submarine.

8 March 1944:
Arrives at Truk.

17 March 1944:
Departs Truk on her ninth war patrol to an N of the Mortlock (Nomoi) Islands that lie SE of Truk.

20 March 1944:
Redirected to an area SE of the Mortlock Islands.

24 March 1944:
Returns to Truk.

29 March 1944:
Departs Truk for her tenth war patrol to the area E of Brown Island.

20 April 1944:
Returns to Truk.

30 April 1944:
Departs Truk to intercept an enemy task force reported in the vicinity.

3 May 1944:
Returns to Truk.

15 May 1944:
Lt Uda Keitai (66)(former torpedo officer of I-16) assumes command. LtCdr Nakamura is later reassigned as CO of I-365 on which he is KIA in Nov '44.

16 May 1944:
Departs Truk on her eleventh war patrol to form a picket line N of the Admiralty Islands to warn of American invasion forces approaching the Palaus. MIA thereafter.

18 May 1944:
The U. S. Navy intercepts radio traffic that indicates the Japanese have established a new submarine picket "NA line" between Truk and the Admiralty Islands to intercept American carriers. LtCdr Walton B. Pendelton's USS ENGLAND (DE-635) departs Purvis Bay, off Florida Island, Solomons with LtCdr James Scott's USS RABY (DE-698) and LtCdr Fred W. Just's GEORGE (DE-697) as a hunter-killer group to attack the NA line.

22 May 1944:
N of the Admiralty Islands. At 0351, GEORGE reports a contact, bearing 303, at 14,000 yards on her SG radar. Shortly thereafter, a blip appears on ENGLAND's screen that looks like a surfaced submarine. GEORGE and RABY are ordered to close and ENGLAND to open out to the NE, to box in the target.

At 4,000 yards, LtCdr Just orders GEORGE's searchlights snapped on. The contact -a surfaced submarine - is illuminated. Lt Uda, whose E27 radar detector failed to detect GEORGE, crash-dives. At 0415, GEORGE makes sonar contact and attacks with a salvo of thrown-ahead Mark 10 "Hedgehog" bombs, but misses the radically maneuvering submarine.

At 0425, ENGLAND makes another sonar contact, bearing 193 at 2,500 yards. At 0444, LtCdr Pendelton attacks with hedgehogs, but also misses. ENGLAND opens the range, turns, and heads back in. The submarine reverses course to meet ENGLAND, bow on. At 0501, Pendelton unleashes another salvo of hedgehogs. His crew hears at least three underwater explosions at 275 feet. This time, ENGLAND kills RO-106 with all hands in 2,700 fathoms of water at 01-40N, 150-31E.

15 June 1944:
Presumed lost N of the Admiralty Islands with all 49 hands.

10 August 1944:
Removed from the Navy List.

Authors' Note:
[1] LST-342 was torpedoed by RO-106 off New Georgia and blown in two. The stern sank immediately, but the bow remained afloat and was towed to Purvis Bay in the islet of Ghavutu of the Ngella (Florida) Islands near Guadalcanal and beached. Later, it was salvaged of any useable equipment. For more info, please see LST-342.

[2] RO-106 may have been the same submarine that USS MAHAN (DD-364) depth-charged off Lae that day.

Special thanks also go to Hans Mcilveen of the Netherlands for research based on wartime FRUMEL intercepts.

Thanks go to Dr. Higuchi Tatsuhiro of Japan. Thanks also go to Rod Dickson for posting info on LST-342 on and to Matthew Jones of the USA.

Bob Hackett and Sander Kingsepp.

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