IJN Submarine RO-42:
Tabular Record of
© 2001-2017 Bob Hackett & Sander Kingsepp
27 April 1942:
Sasebo Navy Yard. Laid down as a 960-ton type K6 submarine.
25 June 1943:
LtCdr (later Cdr, posthumously) Wada Mutsuo (61) (former CO of I-153) is posted Chief Equipping Officer.
25 October 1943:
Launched and designated RO-42.
31 August 1943:
Completed and attached to the Maizuru Naval District in SubRon 11. LtCdr 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, Solomons.
14 January 1944:
200 miles E of Espiritu Santo. RO-42 torpedoes 800-ton harbor craft USS YO-159 at 15-27S, 171-28 E. The damaged fuel-oil barge is later scuttled by U. S. forces. Wada reports his target as a 10,000-ton fleet oiler.
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 Marshalls:
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 Truk:
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 Eniwetok:
The V Amphibious Corps Reserve (Marine 22nd Regiment and the Army's 106th Infantry Regiment) capture Engebi Island, Eniwetok and Parry atolls.
19 February 1944:
Returns to Truk.
25 February 1944:
Departs Truk for the area E of Kusaie on her second war patrol.
1 March 1944:
RO-42 is ordered to reconnoiter Kwajalein, then patrol 120 miles SE of Kwaja.
4 March 1944:
Off Kwajalein. Lt 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. At 0800 (JST), Lt Wada sights a convoy of six transports.
15 March 1944:
70 miles SW of Mille. In the morning, Lt 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 westwards.
21 March 1944:
240 miles S of Ponape. Lt Wada sights a convoy of three vessels.
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. Lt (j.g.) Kudo Yoshinosuke (66)(former XO / Chief Torpedo Officer of I-177)assumes command. LtCdr Wada is later reassigned as CO of I-33, but is killed in a training dive when her main induction valve fails to close.
1 May 1944:
Lt. (j.g.) Kudo is promoted Lt.
15 May 1944:
RO-42 departs Yokosuka with ComSubDiv 34 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.
40 miles E of Roi. At 2330, Lt Cdr C. 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 begins.
13 June 1944: Operation “A-GO” - The Defense of the Marianas:
In 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 the Marianas.
That same day, RO-42 is ordered to proceed to the Marianas area at flank speed.
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. Lt Kudo is promoted LtCdr, posthumously. Captain Yamada Takashi (49) CO of SubDiv 34, is also lost with RO-42. He is promoted Rear Admiral, posthumously.
10 August 1944:
Removed from the Navy List.
 Some sources claim that 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 and to Matt Jones for additional Co info in Rev 3. – Bob Hackett and Sander Kingsepp.
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