(KS type RO-109 scanned from "Submarines of the Imperial Japanese Navy"
by Polmar and Carpenter)
IJN Submarine RO-101:
Tabular Record of
© 2001-2017 Bob Hackett & Sander Kingsepp
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:
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
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 RO-101
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
1 April 1943: Operation "I-GO" - The Reinforcement of Rabaul:
(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, 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 same day.
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:
The RO-101 is ordered to return to Rabaul.
30 June 1943: American Operation "TOENAILS" - The Invasion of New
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. 
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
14 July 1943:
Returns to Rabaul. Repairs last three weeks.
7 August 1943:
Departs Rabaul on her seventh war patrol for the
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
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. 
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 - probably
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
11 October 1943:
Presumed lost with all 50 hands in the Solomons.
1 December 1943:
Removed from the Navy List.
 In all likelihood this was the Dobodura-based B-17E
"Honikuu 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.
 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.
 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.
Back to Submarine