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

IJN Submarine RO-115:
Tabular Record of Movement

© 2001-2016 Bob Hackett & Sander Kingsepp
Revision 2

12 October 1942:
Kobe. Laid down at Kawasaki Jukogyo K.K. as the 525-ton Kaisho (KS) Type submarine No. 406.

19 June 1943:
Launched as RO-115.

25 October 1943:
Lt (later LtCdr) Koreeda Sadayoshi (64)(former torpedo officer of I-1) is appointed Chief Equipping Officer.

30 November 1943:
Completed and attached to Yokosuka Naval District. Assigned to SubRon 11. Lt Koreeda is the Commanding Officer.

1 January 1944:
RO-115 is in Rear Admiral Ishizaki Noboru's (42)(former CO of HYUGA) SubRon 11 in Vice Admiral (Admiral, posthumously) Takagi Takeo's (39)(former CO of MUTSU) Sixth Fleet (Submarines).

10 March 1944:
Reassigned to SubDiv 51 of Rear Admiral Owada Noboru's (44)(former CO of YAMASHIRO) SubRon 7.

11 March 1944:
Departs Kure for Truk.

12 March 1944:
Melbourne, Australia. An analysis of IJN traffic provided by USN Fleet Radio Unit Melbourne (FRUMEL) shows RO-115 and I-38 are currently located in Kure.

22 March 1944:
Arrives at Truk.

28 March 1944:
Departs Truk on her first war patrol to an area W of Jaluit.

18 April 1944:
Returns to Truk. Departs soon after arrival to intercept a reported enemy task force.

19 April 1944:
Returns to Truk.

30 April 1944:
Departs Truk to intercept an enemy task force.

3 May 1944:
Returns to Truk.

5 May 1944:
FRUMEL decodes an IJA 18th Army HQ (Wevak) request to C-in-C, Combined Fleet to provide a submarine to transfer important Army documents from Wewak to Palau. The submarine slated for this mission is RO-115.

19 May 1944:
Departs Truk for a supply mission to Wewak.

27 May 1944:
Arrives at Wewak, departs that same day for Palau, carrying a shipment of IJA codes and secret documents.

3 June 1944:
Arrives at Palau where the secret documents are handed over to the 30th Base Unit HQ.

7 June 1944:
Departs Palau on her second war patrol to join a patrol line N of New Ireland.

13 June 1944: Operation "A-Go": The Defense of the Marianas:
Admiral Toyoda Soemu (33)(former CO of HYUGA), CINC, Combined Fleet, activates A-Go and orders Vice Admiral Takagi to redeploy his boats to the Marianas. From his headquarters on Saipan, Takagi orders all available submarines to deploy to the east of the Marianas.

14 June 1944:
Receives an order to proceed to a new position S of Guam at flank speed.

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 between Takagi's Advance Expeditionary Force (Sixth Fleet) are disrupted by the invasion. Command of the Sixth Fleet's submarines passes to Rear Admiral Owada at Truk.

16 June 1944:
Reassigned to the "C" patrol unit with RO-113, RO-114 and RO-117. Ordered to assume a new position NW of Rota Island, Marianas.

19 June 1944:
550 miles NW of Rota. In the morning, Lt Koreeda sights two groups of enemy carriers and starts a chase. At 1807 (JST), RO-115 fires four torpedoes at an unidentified "SARATOGA-class” carrier, but fails to score any hits. RO-115 is briefly depth-charged, but manages to escape. She is then ordered to return to Truk.

27 June 1944:
Arrives at Truk.

7 July 1944:
Departs Truk for Yokosuka.

17 July 1944:
Arrives at Yokosuka.

5 August 1944:
Lt (promoted LtCdr 1 November 1944; Cdr, posthumously) Chikuma Chuzo (65)(former CO of RO-63) is appointed CO.

10 August 1944:
Departs Yokosuka for Penang, Malaya.

15 August 1944:
SubDiv 51 is disbanded. RO-115 is reassigned to Rear Admiral Uozumi Jisaku's (42)(former CO of HAGURO) SubRon 8 at Penang with the RO-113.

20 October 1944: American Operation "KING TWO" - The Invasion of Leyte, Philippines:
Admiral (later Fleet Admiral) William F. Halsey's (USNA ’04) 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 begin the campaign to retake Leyte.

23 October 1944: Operation "TA" - The Reinforcement of Leyte:
Vice Admiral Mikawa Gun'ichi (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 convoys attempt the 600-mile passage from Manila to Ormoc Bay, Leyte.

25 October 1944:
Departs Penang on her third war patrol to raid enemy communications in the Bay of Bengal.

29 October 1944:
Based on the IJN traffic analysis, FRUMEL reports that RO-115 was attacked by an aircraft in 15-28N, 090-15E on the 28th and possibly sunk. [1]

8 November 1944:
Returns to Penang.

7 December 1944:
At 1700 (local) departs Penang on her fourth war patrol to raid enemy communications in the Bay of Bengal, off Madras.

28 December 1944:
Returns to Penang. On that same day, FRUMEL reports that RO-115 is currently operating in the area between Madras and Calcutta.

9 January 1945: American Operation "MIKE ONE" - The Invasion of Luzon, Philippines:
Lingayen Gulf. Vice Admiral (later Admiral) Thomas C. Kinkaid's (USNA ’08) Task Force 77 lands almost 175,000 men of General 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 the campaign to retake Luzon from General Yamashita Tomoyuki's defenders.

19 January 1945:
Departs Penang for Singapore.

21 January 1945:
Arrives at Singapore.

22 January 1945:
Departs Singapore on her fifth war patrol to the area W of Luzon. No messages are received from RO-115 after her departure.

31 January 1945:
125 miles SW of Manila. Cdr J. S. Gabbert's USS BELL (DD-587), LtCdr J. A. Pridmore's O'BANNON (DD-450), LtCdr P. D. Gallery's JENKINS (DD-447) and LtCdr Franklin D. Roosevelt Jr's (son of the President) USS ULVERT M. MOORE (DE-442) are operating off Mindoro to intercept Japanese transports attempting to make Luzon.

At 1955, the light cruiser USS BOISE (CL-47) makes a surface radar contact. BELL picks up the contact on her SG radar at 9,250 yards. BELL and O'BANNON are detached to investigate the contact. They acquire the target by sonar and attack with depth charges, but then lose contact. The MOORE is detached to assist. Meanwhile, BELL reacquires the target and makes another depth charge attack that results in an oil slick.

Ar 2122, the JENKINS arrives to relieve BELL and LtCdr Gallery takes charge of the hunt. An hour later, LtCdr Roosevelt's MOORE launches the first of five barrages of 24 each ahead-thrown Mark 10 "Hedgehog" projector charges over the oil slick.

1 February 1945:
At 0015, MOORE's last hedgehog barrage sinks the submarine, most likely RO-115, at 13-20N, 119-20E. [2]

3 February 1945:
RO-115 is ordered to proceed to Takao, Formosa, by 6-8 February latest. She is slated to participate in the evacuation of the stranded IJNAF pilots from Luzon, Philippines. The submarine does not respond to that signal. [3]

4 February 1945:
Vice Admiral Miwa Shigeyoshi (39) orders RO-115, RO-46, RO-112 and RO-113 to prepare to participate in the evacuation of the stranded pilots from the Aparri area on Luzon, Philippines. All above submarines are also ordered to land their deck gun ammunition and reserve torpedoes at Takao prior to the rescue mission.

16 February 1945:
FRUMEL decodes the following message timed 171827: "Submarines RO-112 and RO-113 left Takao on 9th and and 10th respectively and were due to arrive at Batulinao on 12th and 14th. RO-115 has not yet returned to Takao from her operating area."

20 February 1945:
RO-115 is reassigned to SubDiv 34.

21 February 1945:
Presumed lost with all 59 hands off the Philippines.

10 May 1945:
Removed from the Navy List.

Authors' Notes:
[1] On 6 November FRUMEL reported that the Sixth Fleet was communicating with RO-115 and correctly surmised that the submarine was still active.

[2] There is some confusion regarding the exact location where RO-115 was sunk. The one given in the above entry is taken from the Official Chronology of the U.S. Navy in World War II by Robert J. Cressman, while USS ULVERT M. MOORE's deck log suggests 15-03N, 119-07E.

[3] One theory implies that RO-115 was among the submarines sunk by USS BATFISH (SS-310) off Luzon between 10 and 13 February. Since RO-115 never arrived at Takao she also never received an order to proceed to Luzon, nor did she undergo the mandatory refit to embark the maximum number of IJNAF pilots. In fact, RO-115's name does not appear in any IJN messages providing the dates of arrival of the submarines to Luzon during that time frame.

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

Special thanks to Hans Mcilveen of the Netherlands for info on FRUMEL intercepts and to Mark W. Allen of Oklahoma for ULVERT MOORE's attack location.

– Bob Hackett and Sander Kingsepp.

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