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

IJN Submarine RO-101:
Tabular Record of Movement

© 2001-2017 Bob Hackett & Sander Kingsepp
Revision 3

30 September 1941:
Kobe. Laid down at Kawasaki Jukogyo K.K. as a 525-ton (standard) Kaisho (KS) Type submarine No. 211.

17 April 1942:
Launched as RO-101.

20 July 1942:
Lt (later Captain, JMSDF) Orita Zenji (59)(former CO of I-156) is appointed the Chief Equipping Officer (CEO) of RO-101 and RO-102 (until 15 October 1942) as an additional duty.

10-30 September 1942:
Lt (promoted LtCdr 1 November) Orita is appointed the CEO of I-177 as an additional duty.

31 October 1942:
Completed and assigned to the Kure SubRon. Lt Orita is the Commanding Officer. Works up in Inland Sea, then proceeds to Yokosuka.

16 January 1943:
Reassigned to Rear Admiral (later Vice Admiral) Harada Kaku's (former CO of CVS CHIYODA) SubRon 7 in SubDiv 13, in Vice Admiral Mikawa Gunichi's (former CO of KIRISHIMA) Eighth Fleet at Rabaul.

18 January 1943:
Departs Yokosuka.

25 January 1943:
Arrives at Truk.

4 February 1943: Operation "KE-GO" - The Evacuation of Guadalcanal.
Departs Truk on her first war patrol to an area E of Port Moresby, New Guinea to provide distant cover during Operation "KE-GO".

8 February 1943:
Arrives at Rabaul.

9 February 1943:
Departs Rabaul with RO-103 on her second war patrol to an area E of Port Moresby.

22 February 1943:
RO-101's navigator, Lt(jg) Koyama Sakuma, sights a 4,000-ton steamer. After examining the target by persicope, LtCdr Orita determines that it is a "Q" ship - a merchant armed with hidden guns and depth charges. He decides to make a night attack, but the ship speeds off towards Port Moresby and escapes.

25 February 1943:
Departs the patrol area.

28 February 1943:
Returns to Rabaul.

2 March 1943: The Battle of the Bismarck Sea:
A convoy of Supply Operation No. 81 under Rear Admiral (later Vice Admiral) Kimura Masatomi (former CO of SUZUYA) is en route to Lae, New Guinea with troops of the IJA's 51st Division embarked. Over the next three days, the convoy is bombed and strafed repeatedly by USAAF and RAAF planes. All of the eight transports and cargo vessels in the convoy and four of the eight escorting destroyers are sunk. Hundreds of IJA soldiers in lifeboats, rafts and in the water are machine-gunned by planes and PT boats.

4 March 1943:
In the afternoon RO-101 departs Rabaul to rescue survivors of Admiral Kimura's troop convoy.

7 March 1943:
S of Dampier Strait, Northern New Guinea. RO-101 rescues Captain Matsumoto Kametaro, CO of collier NOJIMA and 44 IJA infantrymen from lifeboats.

8 March 1943:
Returns to Rabaul. Departs that same day to rescue Lt Ichimura Rikinosuke's RO-103, grounded off Kiriwina Island.

11 March 1943:
RO-103 breaks free from the reef before Orita's submarine arrives. RO-101 is recalled to Rabaul.

19 March 1943:
Departs Rabaul for the area SE of Guadalcanal. Soon after departure most of the crew fall sick with food poisoning and the patrol has to be aborted.

21 March 1943:
Departs Rabaul on her third war patrol for the Solomon Islands to gather weather data, perform air-sea rescue and attack enemy shipping.

1 April 1943: Operation "I-GO" - The Reinforcement of Rabaul:
Admiral (Fleet Admiral, posthumously) Yamamoto Isoroku (former CO of AKAGI), CINC Combined Fleet, orders aircraft from CarDiv 1's ZUIKAKU and ZUIHO to reinforce Vice Admiral Kusaka Jinichi's (former CO of FUSO) 11th Air Fleet's base at Rabaul. Yamamoto also orders aircraft from CarDiv 2's HIYO and JUNYO to reinforce the base at Ballale Island, near Buin, Bougainville.

5 April 1943:
RO-101 is ordered to proceed to Cape Esperance, Guadalcanal and rescue a downed bomber crew, but Orita is held off by American PT-boats and has to abort the mission.

12 April 1943:
Returns to Rabaul.

30 April 1943:
Departs Rabaul on her fourth war patrol for the Samarai Bight, New Guinea.

10 May 1943:
Arrives to the patrol area SE of Rabi, New Guinea, formerly assigned to RO-102.

17 May 1943:
Departs her patrol area.

21 May 1943:
W of Cape St. George. Around 0340, the returning RO-101 sights a four-engined bomber, going down in flames. Two parachutes originating from the same plane are likewise observed. Returns to Rabaul on that day. [1]

8 June 1943:
Prior to departure from Rabaul to patrol E of Guadalcanal, RO-101 is fitted with a E27/Type 3 radar detector.

12 June 1943:
Arrives at her patrol area.

17 June 1943:
Redirected to the Gatukai –Munda area.

29 June 1943:
RO-101 is ordered to return to Rabaul.

30 June 1943: American 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, LtCdr Orita, submerged off Munda, reports sighting enemy landing craft to ComSubRon 7, Rear Admiral Harada, at Rabaul. RO-101 is ordered to approach and attack the Munda beachhead from the W of Rendova. Orita attempts to penetrate the PT-Boats ringed around the landing site, but cannot.

2 July 1943:
Orita attempts again to attack the landing beach, but still cannot penetrate the PT-Boat defense. He withdraws to sea to charge his batteries at night, but receives orders to return to Rabaul.

3 July 1943:
Returns to Rabaul.

8 July 1943:
Departs Rabaul on her sixth war patrol to penetrate the Rice Anchorage, Kula Gulf.

12 July 1943:
Kula Gulf. RO-101 is on the surface recharging her batteries at approximately 08-00S, 157-19E. At 1650, Cdr (later Rear Admiral-Ret) Benjamin Katz's USS TAYLOR (DD-468), escorting a convoy, picks up a contact on her SG radar.

At 1654, the destroyer's lookouts have a visual ID on the submarine’s conning tower 2,500 ft away. TAYLOR illuminates the target with her searchlight and opens fire. RO-101's torpedo officer, Lt Tokugawa Hiromu (65) and two lookouts are killed with the first hits. LtCdr Orita has to drag their bodies away before he can descend into the conning tower and close the upper hatch, so that the submarine can finally dive. RO-101 dives to 460 feet. Orita orders the main tanks blown in an attempt to stop the sinking. [2]

At 1710, TAYLOR drops two more depth-charges that render periscope No. 1 inoperable. RO-101 remains submerged for the next two hours. The temperature aboard rises to +104 F (+40 C). Towards evening, RO-101 surfaces and proceeds to the NW coast of Kolombangara Island for makeshift repairs.

Inspection of the boat indicates numerous dents in the hull and that the periscope must be replaced. After sunset, her crew hears heavy gunfire and observes several searchlight beams (Battle of Kolombangara). RO-101 is ordered to rescue the survivors from JINTSU, but can not execute it.

13 July 1944:
W of Shortland Island. In the afternoon, while charging her batteries, RO-101 is attacked by a patrol plane. Orita crash-dives. The plane misses the diving sub with two bombs, but her second periscope is also rendered inoperable.

14 July 1943:
Returns to Rabaul. Repairs last three weeks.

7 August 1943:
Departs Rabaul on her seventh war patrol for the Kolombangara area.

18 August 1943: The Battle off Horaniu:
Rear Admiral (Vice Admiral, posthumously), the Baron, Ijuin Matsuji (former CO of KONGO) leads SAZANAMI (F), HAMAKAZE, ISONAMI and SHIGURE screening 13 Daihatsu barges and three motor torpedo boats. They are carrying IJA and SNLF troops from Buin to Horaniu on Vella Lavella, Bougainville.

Captain Thomas Ryan is dispatched to intercept the Japanese with the NICHOLAS (DD-449), O'BANNON (DD-450), CHEVALIER (DD-451) and TAYLOR (DD-468). At 0040, a Japanese scout plane drops flares and illuminates the American destroyers 15,000 yards W of the convoy. Between 0046 and 0055, Ijuin's destroyers launch 31 torpedoes at the Americans, but Ryan turns into them and they all miss. Both sides open fire, but the range is long and the gunfire is ineffective. The convoy scatters. Admiral Ijuin withdraws to the NW. Ryan sinks two small subchasers, but the barges later rescue 9,000 Japanese troops from Kolombangara.

About 0100, in RO-101, LtCdr Orita spots gunfire flashes to the north through his periscope. At 0200, his sound operator picks up destroyer screws coming down the "Slot". Orita quickly sets up and at a range of only 600 yards fires four torpedoes at the second destroyer, but they all pass astern! The destroyer is making 30 knots, much faster than Orita calculated.

20 August 1943:
RO-101 is reassigned to SubDiv 51 with RO-100. Lt Arima Fumio (64)(former torpedo officer of I-175) is notified of his appointment as the next CO of RO-101.

26 August 1943:
RO-101 returns to Rabaul with RO-100, RO-103 and RO-106. LtCdr Orita receives a signal that he is being reassigned.

28 August 1943:
Bougainville. A Kawanishi H6K "Mavis" is shot down by Lt Charles J. Alley's PB4Y-1 "Liberator" of the VB-104's "Buccaneers" based at Guadalcanal. The Mavis was transporting several passengers from Truk to Rabaul including the prospective CO of RO-101, Lt Arima who is KIA.

1 September 1943:
Lt (LtCdr, posthumously) Fujisawa Masanori (63) (former torpedo officer of I-180) is appointed the CO. [3]

4 September 1943:
Lt Fujisawa assumes command.

10 September 1943:
RO-101 departs Simpson Harbor, Rabaul on her eighth war patrol to patrol SE of San Cristobal, Solomons.

15 September 1943:
S entrance to Indispensable Strait, Guadalcanal. A submarine attacks a convoy of two cargo ships en route to Espiritu Santo. At 1011, the convoy's escorts, old four-stack minelayer USS MONTGOMERY (DD-121) and Cdr B. F. Brown's new SAUFLEY (DD-465) sight a torpedo wake. MONTGOMERY's sound gear is inoperative, so SAUFLEY begins to search down the track of the torpedo's wake. At 1251, she makes sonar contact at 3,000 yards.

Over the next three and one-half hours, SAUFLEY makes five depth charge attacks. At 1443, the submarine surfaces. SAUFLEY's five-inch batteries and machine guns open up on her conning tower. Overhead, Lt W. J. Geritz's PBY-5 "Catalina" patrol bomber of VP-23 joins the attack and drops two depth charges. The first charge misses, but the second hits. At 1446, the submarine - in all likelihood RO-101 - disappears, then the destroyer's crew hears a heavy underwater explosion. By 1735, a diesel oil slick covers a square mile of the ocean at 10-57S, 163-56E.

11 October 1943:
Presumed lost with all 50 hands in the Solomons.

1 December 1943:
Removed from the Navy List.

Authors' Note:
[1] In all likelihood this was the Dobodura-based B-17E "Honi Kuu Okole" of the 64th Bombardment Squadron, 43rd Bombardment Group, flown by Maj. Paul I. Williams, and shot down by a J1N1 "Irving" night fighter from the 251st NAG, piloted by CPO Kudo Shigetoshi.

[2] Various sources mistakenly credit USS TAYLOR with sinking of I-25 or RO-107 on that date. Orita & Harrington (1976) identify the torpedo officer of RO-101 as Lt Tokugawa Hiromi; the Tokugawa family register, however, lists him as Tokugawa Hiromu.

[3] Orita & Harrington identify the officer in question as Fujisawa Masataka. The Japanese Navy List of 1937 (p. 303), however, identifies that same officer as Fujisawa Masanori.

Thanks go to Dr. Higuchi Tatsuhiro of Japan.

– Bob Hackett and Sander Kingsepp.

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