IJN Submarine I-46: Tabular Record of Movement

2001-2018 Bob Hackett & Sander Kingsepp
Revision 1

21 November 1942:
Laid down at Sasebo Navy Yard as Submarine No. 376, the lead boat of the C2 subtype.

25 May 1943:
Numbered I-46.

3 June 1943:
Launched and provisionally attached to Yokosuka Naval District.

23 December 1943:
LtCdr (Cdr, posthumously) Yamaguchi Kozaburo (59)(former CO of I-176) is appointed the ad hoc Chief Equipping Officer (CEO).

1 February 1944:
LtCdr Yamaguchi is reassigned as the CEO of I-46.

29 February 1944:
I-46 is completed, commissioned in the IJN and attached to Yokosuka Naval District. Assigned to SubRon 11 for working-up. LtCdr Yamaguchi Kozaburo is the Commanding Officer.

2 April 1944:
Off Minase Bight, Iyo Sea. During a training sortie, I-46 collides underwater with RO-46 and suffers damage to her conning tower and periscopes.

3 April 1944:
At 0430, USN codebreakers intercept and decrypt a message that reads:
"1. While this unit was carrying out picket patrol duty 2 April, I-46 and RO-46 had underwater collision at 2145, --- distance to southwest of Kominasa Light. 2. Damage summary: I-46, 2 periscopes damaged. Part of --- slightly damaged. RO-46 --- (blanks) --- diving (planes?) damaged. (Expect docking will be necessary)."

7 May 1944:
After initial testing returns to Sasebo Navy Yard for repairs.

30 May 1944:
Reassigned to SubDiv 15, Sixth Fleet (Submarines).

12 August 1944:
LtCdr Yamaguchi submits a memo to the Sixth Fleet HQ and ComSubRon 11, suggesting improvements related to the Type 13 air-search radar installation and the application of the anti-radar coating. [1]

13 October 1944: Operation "SHO-1-GO" - The Defense of the Philippines:
Tokyo. Admiral Toyoda Soemu, CinC, Combined Fleet, orders the "Sho-1-Go" plan activated.

19 October 1944:
Departs Kure on her first war patrol to take up station 120 miles E of Leyte, Philippines with the "B" Group. Her assigned sector is the westernmost one, next to that assigned to I-54.

20 October 1944: American Operation "King Two" - The Invasion of Leyte:
Admiral (later Fleet Admiral) William F. Halsey's (former CO of SARATOGA, CV-3) Third Fleet of 738 ships including 18 aircraft carriers, six battleships, 17 cruisers, 64 destroyers and over 600 support ships land the Army's X Corps (24th Infantry and 1st Cavalry Divisions) and the XXIV Corps (7th, 77th and 96th Infantry Divisions) that begins the campaign to retake Leyte.

24 October 1944:
Vice Admiral Miwa Shigeyoshi, Commander, Sixth Fleet orders I-46 and ten other submarines to converge in an area from Samar to Surigao Strait, Philippines.

25 October 1944:
E of Leyte. Around 0645, I-46 is forced to dive by a patrol aircraft and chased by an enemy vessel identified by her propeller noises as a destroyer for the next eleven hours. Over 200 distant depth charge explosions are recorded during that time.

26 October 1944:
LtCdr Yamaguchi reports sighting a small enemy convoy to the E of his assigned station. It is the last signal received from I-46.

27 October 1944:
Headquarters, Sixth Fleet orders I-46 to proceed to a new station to the E of Leyte, but the signal is not acknowledged by LtCdr Yamaguchi.

28 October 1944:
E of Leyte. Cdr Selby K. Santmyers' USS HELM (DD-388) is part of the screen of Rear Ralph E. Admiral Davison's carrier Task Group 38.4 (USS ENTERPRISE (CV-6), FRANKLIN (CV-13), BELLEAU WOOD (CVL-24) and SAN JACINTO (CVL-30), providing direct support to ground operations on Leyte.

At 1218, HELM and Cdr Philip D. Quirk's USS GRIDLEY (DD-380) detect a submarine trying to penetrate TG 38.4's screen. As Davison's carriers clear the area at high speed, the two destroyers carry out depth charge attacks. HELM's 4th attack at 1411 brings a heavy explosion, followed by two smaller ones with oil and air bubbles rising to the surface. GRIDLEY makes three depth charge attacks.

Their target, either I-46 or I-54 is sunk at 10-58N, 127-13E. Splintered deck planking and human remains are recovered after the attack. [2]

30 October 1944:
At 1900 (JST), all IJN submarines stationed E of Leyte report their respective locations to Sixth Fleet HQ. I-46, I-26 and I-54 fail to answer.

1 November 1944:
At 1900 (JST), I-46, I-26 and I-54 fail to report for the second time.

2 December 1944:
Presumed lost with all 112 hands E of the Philippines.

10 March 1945:
Removed from the Navy List.

Authors' Notes:
[1] In all likelihood Type 22 surface-search radar was likewise installed by that time.

[2] Both I-46 and I-54 have been identified as the submarine lost in the 28 October attack. Orita and Harrington (1976) suggest that I-46 was sunk by [LAWRENCE C.] TAYLOR, evidently confusing her with I-41.

Special thanks for help in preparing this TROM go to Dr. Higuchi Tatsuhiro of Japan. Bob Hackett and Sander Kingsepp.

Thanks also go to John Whitman of the USA for info on CNO intercepts of Japanese messages.

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