IJN Submarine RO-40:
Tabular Record of Movement

© 2001-2017 Bob Hackett & Sander Kingsepp
Revision 3

8 August 1942:
Laid down at Mitsubishi's Kobe Yard as a 960-ton type K6 Submarine No. 206.

5 February 1943:
Renumbered RO-40 and provisionally attached to Maizuru Naval District.

6 March 1943:

1 August 1943:
LtCdr (Cdr, posthumously) Kido Yasuo (60)(former CO of RO-58) is appointed the Chief Equipping Officer (CEO).

28 September 1943:
Kobe. RO-40 is completed, comissioned and attached to Maizuru Naval District. Assigned to SubRon 11 for working-up. LtCdr Kido Yasuo is the Commanding Officer.

5 October 1943:
Inland Sea, 3 miles off Murozumi Lighthouse. During a training cruise RO-40 collides with the sailing vessel OKAKI MARU. Both ships receive minor damage.

20 November 1943: American Operation "GALVANIC" - The Invasion of the Gilberts:
Forces under Vice Admiral (later Admiral) Raymond A. Spruance (USNA '06), Commander, Central Pacific, invade and capture Tarawa and Makin Islands.

2 December 1943:
Arrives at Tokuyama Fuel Depot. Refuels.

4 December 1943:
Departs Tokuyama.

1 January 1944:
RO-40 is in Rear Admiral Owada Noboru’s (44)(former CO of YAMASHIRO) SubRon 7 in SubDiv 11 with I-42, I-43, I-52, I-183, I-184 and RO-41, RO-43, RO-113 and RO-114.

15 January 1944:
Reassigned to SubDiv 34, Sixth Fleet.

20 January 1944:
Departs Maizuru.

29 January 1944:
Arrives at Truk.

31 January 1944: American Operation "FLINTLOCK" - The Invasion of the Marshall Islands:
Vice Admiral (later Admiral) Marc A. Mitscher's (USNA ’10) Task Force 58 lands the 4th Marine Division and the Army's 7th Infantry Division that capture Kwajalein, Roi-Namur and Majuro.

12 February 1944:
RO-40 departs Truk for the Makin area. No messages are received from her thereafter.

12 February 1944:
Departs Truk for an area E of Gilberts via Marshalls on her first war patrol.

16 February 1944:
45 miles NW of Kwajalein, Marshall Islands. A submarine makes an approach on a American convoy. At 1742, LtCdr D. L. Martineau's USS PHELPS (DD-360) makes sonar contact at 1,700 yards. PHELPS drops a pattern of 13 depth charges on the contact. Cdr J. W. Ramey's MACDONOUGH (DD-351) and Lt F. K. Zinn's minesweeper SAGE (AM-111) then join the hunt and lay patterns of depth charges that sink a submarine - probably RO-40 - at 09-50N, 166-35E.

20 February 1944:
The CINC, Sixth Fleet, Vice Admiral (Admiral, posthumously) Takagi Takeo (39)(former CO of MUTSU) redirects RO-40 into an area between Kwajalein and Brown Island to raid enemy supply routes between Hawaii, Tarawa and Makin.

4 March 1944:
RO-40 fails to acknowledge the order to return.

28 March 1944:
Presumed lost with all 69 hands in the Gilberts area.

30 April 1944:
Removed from the Navy List.

Authors' Note:
Thanks go to Dr. Higuchi Tatsuhiro of Japan.

– Bob Hackett and Sander Kingsepp

Back to Submarine Page