(Kaichu type submarine scanned from "Submarines of the Imperial Japanese Navy" by Polmar and Carpenter)

IJN Submarine RO-40:
Tabular Record of Movement

© 2001-2011 Bob Hackett & Sander Kingsepp
Revision 2

28 September 1943:
Kobe. RO-40 is completed at Mitsubishi Shipbuilding's yard and registered in the Maizuru Naval District. LtCdr Kido Yasuo (60) is the Commanding Officer. Attached to SubRon 11 for workup and training.

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:
The 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. Lt Kido is posthumously promoted LtCdr.

30 April 1944:
Removed from the Navy List.

Authors' Note:
Thanks go to Dr. Higuchi Tatsuhiro of Japan and to Matt Jones for additional CO info in Rev 2.

– Bob Hackett and Sander Kingsepp

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