(Kaichu type submarine scanned from "Submarines of the
Imperial Japanese Navy" by Polmar and Carpenter)
IJN Submarine RO-42:
Tabular Record of
© 2001-2016 Bob Hackett & Sander Kingsepp
27 April 1942:
Sasebo Navy Yard. Laid down as a 960-ton
type K6 submarine.
25 June 1943:
Lt (promoted LtCdr 1 November 1943; Cdr, posthumously)
Wada Mutsuo (61)(former CO of I-153) is appointed Chief Equipping Officer.
25 October 1943:
Launched and designated RO-42.
31 August 1943:
Completed and attached to Maizuru Naval District.
Assigned to SubRon 11 for working-up. Lt Wada is the Commanding Officer.
30 November 1943:
RO-42 is reassigned to Captain (Rear Admiral,
posthumously) Shimizu Taro's (48) SubDiv 34, Sixth Fleet.
4 December 1943:
12 December 1943:
Arrives at Truk.
23 December 1943:
Departs Truk to patrol off Espiritu Santo,
14 January 1944:
200 miles E of Espiritu Santo. RO-42 torpedoes
the 800-ton harbor craft USS YO-159 at 15-27S, 171-28 E. The crippled fuel-oil
barge is later scuttled by PC-1138. Wada reports his target as a 10,000-ton
24 January 1944:
Returns to Truk.
28 January 1944:
Truk. HEIAN MARU transfers torpedoes to RO-42.
31 January 1944: American Operation "FLINTLOCK" - The Invasion of the
Task Force 58 lands the 4th Marine Division and the Army's 7th
Infantry Division. They capture Kwajalein, Roi-Namur and Majuro.
17 February 1944: American Operation "HAILSTONE" - The Attack on
Task Force 58's five fleet carriers and four light carriers, supported
by six battleships, ten cruisers and 28 destroyers, launch air attacks on
Japanese ships in the lagoon, airfields and shore installations. In two days of
raids, they sink 31 transports and 10 naval vessels (two cruisers, four
destroyers and four auxiliary vessels), destroy nearly 200 aircraft and damage
severely about 100 more.
That day, the RO-42 departs Truk with RO-36 and I-10 to intercept the
attacking task force.
18 February 1944: American Operation "CATCHPOLE" - The Invasion of
The V Amphibious Corps Reserve (Marine 22nd Regiment and the
Army's 106th Infantry Regiment) capture Engebi Island, Eniwetok and Parry
19 February 1944:
Returns to Truk.
25 February 1944:
Departs Truk for the area E of Kusaie on her second
1 March 1944:
RO-42 is ordered to reconnoiter Kwajalein, then patrol
120 miles SE of Kwajalein.
4 March 1944:
Off Kwajalein. LtCdr Wada reports that the island is
heavily guarded by enemy patrol craft and he cannot approach the coast. After
several technical malfunctions he receives the order to return.
6 March 1944:
40 miles SW of Mili Atoll, Marshalls. At 0800 (JST),
LtCdr Wada sights a convoy of six transports.
15 March 1944:
70 miles SW of Mili. In the morning, LtCdr Wada reports
the sighting of a battleship and five carriers (TG 50.10). Vice Admiral Takagi
Takeo (39) directs RO-36 and RO-44 to intercept the force.
16 March 1944:
RO-42 is ordered to assume a new position 100 miles
out at bearing 240.
18 March 1944:
RO-42 is ordered to take up a position 80 miles
21 March 1944:
240 miles S of Ponape. LtCdr Wada sights a convoy of
23 March 1944:
60 miles N of Jaluit. I-32, under LtCdr Imoto
Masayuki, sights an American task force. RO-42, RO-36, RO-41, RO-43, RO-44 and
RO-108 and I-16 are diverted to intercept it.
28 March 1944:
Returns to Truk.
12 April 1944:
Departs Truk to intercept an enemy task force sighted
N of Kavieng with the RO-36, RO-48, RO-108 and the I-174.
14 April 1944:
Returns to Truk.
23 April 1944:
Departs Truk for Yokosuka.
30 April 1944:
Arrives at Yokosuka.
14 May 1944:
Lt (LtCdr, posthumously) Kudo Yoshinosuke (66)(former
torpedo officer of I-177) is appointed CO.
15 May 1944:
RO-42 departs Yokosuka with ComSubDiv 34, Captain Yamada
Takashi (49) embarked. Her mission is to reconnoiter Majuro and then to proceed
to NNE of Kwajalein, Marshall Islands, prior to the launch of Operation
"A-GO". The Majuro mission is later postponed until 10 June.
10 June 1944:
Marshall Islands. RO-42 is ordered to reconnoiter
Kwajalein and Majuro.
60 miles E of Roi. At 2330, LtCdr Charles F. MacNish's, USNR, USS
BANGUST (DE-739) makes a surface contact with her SL radar. Her Officer of the
Deck visually sights a submarine and blinks a challenge. The submarine crash-dives.
BANGUST remains at General Quarters for the next eight hours, then
regains contact. The submarine uses full evasive tactics with full rudder throws
and sudden changes of speed. BANGUST makes three unsuccessful attack runs with
barrages of twenty-four Mark 10 "hedgehog" projector charges. On her fourth run,
a tremendous underwater explosion cracks a seam in BANGUST's hull. The submarine
tries to surface, but contact is lost. In the morning, a large oil slick is
seen. RO-42 sinks at 10-05N, 168-22E. 
12 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 of Saipan
13 June 1944: Operation “A-GO” - The Defense of the Marianas:
Tokyo, the CINC, Combined Fleet, Admiral Toyoda Soemu (33), (former CO of
HYUGA), activates A-GO and orders Vice Admiral Takagi Takeo (former CO of
MUTSU), CINC, Sixth Fleet (Submarines) to redeploy his boats to the Marianas
from the area bounded by Palau, Mindanao and New Guinea. From his Headquarters
on Saipan, Takagi orders all 18 available submarines to deploy to the east of
That same day, RO-42 is ordered to proceed to the Marianas area at flank
16 June 1944:
RO-42 is redirected to an area SE of Marianas and
temporarily assigned to B Group.
22 June 1944:
RO-42 is ordered to return to Truk.
12 July 1944:
Presumed lost with all 73 hands.
10 August 1944:
Removed from the Navy List.
 According to older sources RO-42 was sunk on 16 September
1944 off Japan by USS SEA DEVIL (SS-400), but this was most probably I-364.
Thanks go to Dr. Higuchi Tatsuhiro of Japan.
– Bob Hackett and Sander Kingsepp.
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