SENSUIKAN!

© 2001-2011 Bob Hackett & Sander Kingsepp
Revision 2

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

5 May 1943:
Launched and designated RO-48.

31 March 1944:
Kobe. Completed and registered (commissioned) in the Maizuru Naval District. Lt (later Cdr) Kazutomi Seita (63)(former XO/Torpedo Officer of I-66) is the Commanding Officer. That same day, RO-48 is reassigned to SubRon 11 for training.

13 June 1944: Operation "A-GO" - The Defense of the Marianas:
Tokyo. Admiral Toyoda Soemu (33)(former CO of HYUGA), CINC, Combined Fleet, activates A-Go and orders Vice Admiral Takagi Takeo (39)(former CO of MUTSU), CINC, Sixth Fleet, to redeploy his boats to 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 LtGen Holland M. Smith's V Amphibious Corps and the invasion begins.

July 1944:
Communications between Takagi's Sixth Fleet on Saipan are disrupted by the invasion. Command of the Sixth Fleet's submarines passes to Rear Admiral Owada Noboru (44)(former Co of YAMASHIRO), ComSubRon 7 at Truk. He orders most of the Sixth Fleet's submarines to withdraw from the Marianas.

3 July 1944:
RO-48 is assigned to SubDiv 34, Sixth Fleet (Submarines).

5 July 1944:
Departs Kure on her first war patrol for her assigned area off Saipan.

10 July 1944:
Vice Admiral Vice Admiral Miwa Shigeyoshi (39)(former CO of KINU) at Kure assumes command of the Sixth Fleet from Rear Admiral Owada at Truk.

12 July 1944:
Arrives at her assigned area within 200 nms of Saipan. Receives a new order to stand by to rescue IJN pilots from Tinian.

14 July 1944:
At 2130 (JST) when stationed 30 nms N of Saipan, LtCdr Kazutomi reports that he had been forced underwater and is in process to change his position.

16 July 1944:
Headquarters, Sixth Fleet orders RO-48 to return.

18 July 1944:
300 miles E of Saipan. Captain W. V. Saunders' USS HOGGATT BAY's (CVE-75) task group 12.2, a hunter-killer group, is conducting antisubmarine warfare (ASW) operations off the Marianas. The carrier's radar picks up a contact on the surface at 21,000 yards.

19 July 1944:
At 0024, Captain Saunders detaches two of his four screening escorts, LtCdr E. P. Parker's USS WYMAN (DE-38) and REYNOLDS (DE-42), to investigate the carrier's radar contact. WYMAN closes the range until 0046 when she loses radar contact at 4,000 yards as the contact dives.

WYMAN switches to her sonar and picks up a strong echo at 1,600 yards. At 0051, Parker fires a barrage of twenty-four Mark 10 "hedgehog" projector charges, but without results. WYMAN reloads and Parker opens the range, then he closes for a second attack.

At 0125, Parker fires a second barrage of twenty-four hedgehogs. WYMAN is rocked by five underwater explosions as the hedgehogs blow the submarine apart. Parker attempts to regain sonar contact but the sonar's returns indicate that the contact has been destroyed. The submarine - probably RO-48 - is sunk E of Saipan at 13-01N, 151-58E.[1]

The submarine is not yet dead. LtCdr Kazutomi signals that RO-48 has undergone a severe depth charging and was forced to leave her station N of Saipan. This is the last message received from RO-48.[1]

July 1944:
Presumed lost with all 76 hands off Saipan. Lt Kazutomi is posthumously promoted two ranks to Cdr.

10 October 1944:
Removed from the Navy List.

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Authors' Note:
[1] RO-48 may or may not have been sunk by WYMAN. Some sources claim RO-48 was sunk on 19 July 1944 E of Guam by a hunter-killer group of USS GILMER (APD-11) and WILLIAM C. MILLER (DE-259).

Thanks go to Dr. Higuchi Tatsuhiro of Japan and to Matt Jones for additional CO info.

– Bob Hackett and Sander Kingsepp

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