(Type B2 submarine)
IJN Submarine I-40: Tabular Record of
© 2001-2017 Bob Hackett & Sander Kingsepp
18 March 1942:
Laid down at Kure Navy Yard as
Type B2 Submarine
20 August 1942:
Renumbered I-40 and provisionally attached to
Yokosuka Naval District.
10 November 1942:
10 May 1943:
LtCdr (Captain, posthumously) Watanabe Katsuji
(55)(former CO of I-169) is appointed the Chief Equipping Officer (CEO).
31 July 1943:
I-40 is completed, commissioned in the IJN and
attached to Yokosuka Naval District. Assigned to SubRon 11, First Fleet,
for working-up. LtCdr (promoted Cdr 1 November) Watanabe Katsuji is the
Inland Sea, off Kure. I-40 participates in Type 3
sonar and Type 1 Model 3 magnetic anomaly detector (aka the "Y-device")
tests, carried out by the minelayer NUWAJIMA. I-40 plays the role of the ASW
31 Oct 1943:
Reassigned to SubRon 1's SubDiv 2, Sixth Fleet.
13 November 1943:
Departs Yokosuka for Truk.
19 November 1943:
Arrives at Truk.
20 November 1943: American Operation "Galvanic" - The Invasion of the
The Americans invade Tarawa and Makin Islands. The invasion fleet
of 200 ships includes 13 battleships and 11 carriers.
Vice Admiral (Admiral, posthumously) Takagi Takeo (former CO of MUTSU),
CinC, Sixth Fleet (Submarines) orders I-40, -19, -21, -35, -39, -169,
-174, I-175 and RO-38 to proceed to Tarawa to attack the invasion ships.
22 November 1943:
Departs Truk for the Makin area on her first war
patrol, but is MIA thereafter. 
26 November 1943:
Takagi orders I-19, I-40, I-169 and RO-38 to
form a picket line N of Makin.
2 December 1943:
Headquarters, Sixth Fleet sends a signal to I-40,
I-19 and I-20 inquiring as to their respective locations.
21 February 1944:
Presumed lost in the Gilberts with all 97 hands.
30 April 1944:
Removed from the Navy List.
 There are several theories regarding the loss of I-40.
Carpenter and Polmar (1986) credit land-based naval aircraft (p. 36) and
USS RADFORD (DD-446)(p. 106); Boyd and Yoshida (1995) credit USS RADFORD with
her destruction. Alternatively I-40 could have been the victim of USS BOYD
(DD-544) on 26 November (also identified as I-39).
Special thanks for help in preparing this TROM go to Dr. Higuchi
Tatsuhiro of Japan.
– Bob Hackett and Sander Kingsepp.
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