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

IJN Submarine RO-48:
Tabular Record of Movement

2001-2016 Bob Hackett & Sander Kingsepp
Revision 4

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

31 July 1943:
Designated RO-48 and provisionally attached to Maizuru Naval District.

15 October 1943:
Launched. The submarine receives a different conning tower, shaped to reduce the radar incident angle. She is fitted with an E27 Type 3 radar detector prior to the completion.

20 January 1944:
Lt (promoted LtCdr 1 May 1944; Cdr, posthumously) Ichitomi Kiyota (63)(former CO of RO-58) is appointed Chief Equipping Officer.

31 March 1944:
Kobe. Completed and attached to Maizuru Naval District. Lt Ichitomi Kiyota is the Commanding Officer. That same day, RO-48 is assigned to SubRon 11, Sixth Fleet, 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 Ichitomi 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:
360 miles E of Guam. 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 yds.

19 July 1944:
At 0024, Captain Saunders detaches two of his four screening escorts, LtCdr Edwin 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 yds as the contact dives.

WYMAN switches to her sonar and picks up a strong echo at 1,600 yds. 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 "Hedgehog" charges. WYMAN is rocked by five underwater explosions as the submarine is blown 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 at 13-01N, 151-58E. [1][2]

15 July 1944:
Presumed lost with all 76 hands off Saipan.

10 October 1944:
Removed from the Navy List.

Authors' Note:
[1] Some older sources credit USS GILMER (APD-11) and WILLIAM C. MILLER (DE-259) with the sinking of RO-48. In reality, their victim was I-55.

[2] It is possible that USS WYMAN was the attacker of RO-48 on 14 July as well.

Thanks go to Dr. Higuchi Tatsuhiro of Japan.

Bob Hackett and Sander Kingsepp

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