(Type B3/B4 submarine - digitally colorized by Irootoko,
IJN Submarine I-56: Tabular Record of
© 2001-2017 Bob Hackett & Sander Kingsepp
29 September 1942:
Laid down at Yokosuka Navy Yard as Submarine No. 629.
12 June 1943:
Numbered I-56 and provisionally attached to Kure
30 June 1943:
Launched as I-56.
1 April 1944:
Cdr (later Captain) Hori Takeo (50)(chief of the
submarine division at Kure Navy Yard) is appointed the Chief Equipping Officer
(CEO) of I-56 as an additional duty.
15 April 1944:
LtCdr (later Rear Admiral, JMSDF) Morinaga Masahiko
(59)(former CO of I-5) is appointed the CEO.
8 June 1944:
Completed and attached to Kure Naval District. Assigned
to SubRon 11 for working-up. LtCdr Morinaga Masahiko is the Commanding Officer.
20 September 1944:
Reassigned to SubRon 1's SubDiv 15 in Vice Admiral
Miwa Shigeyoshi's (former CO of CL KINU) Sixth Fleet.
Kure. I-56 begins conversion to a "kaiten" human
torpedo carrier. Her 140-mm deck gun is landed. A Type 22 radar and a E27 Type 3
radar detector are also installed at this time, or possibly earlier.
12 October 1944:
Carriers of Vice Admiral (later Admiral) Marc A.
Mitscher's (former CO of HORNET (CV-8) Task Force 38 launch air strikes against
Formosa (Taiwan) and northern Luzon, Philippines. I-56's conversion is halted
and she commences preparations for her first war patrol.
13 October 1944: Operation "SHO-I-GO" - The Defense of the
Admiral Toyoda Soemu, CINC, Combined Fleet, orders the SHO-I-GO
15 October 1944:
I-56, I-26, I-37, I-45, I-53 and I-54 are designated
"Group A", personally led by Vice Admiral Miwa. Group A is originally tasked to
intercept Task Force 38. That day, I-56, accompanied by I-54, departs Kure on
her first war patrol towards an area 240 miles SE of Formosa.
18 October 1944:
I-56 is redirected to an area E of Mindanao,
Philippines. Her ETA is 24 October.
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 (24 th Infantry and 1st Cavalry Divisions) and the XXIV Corps
(7th, 77th and 96th Infantry Divisions) that begin the campaign to retake Leyte.
24 October 1944:
Philippine Sea, E of Mindanao Island. I-56 attacks an
American convoy, firing three torpedoes. Three explosions are heard. LtCdr
Morinaga reports three transports as sunk.
In reality the Tank Landing Ship LST-695, steaming with the New
Guinea-bound TG 78.1, is damaged and later towed to Palau by LST-985. Frigate
CARSON CITY (PF-50) makes an unsuccessful counterattack. 
25 October 1944:
Philippine Sea, NE of Mindanao. At 2234, LtCdr
Morinaga attacks Rear Admiral Thomas L. Sprague's Task Unit 77.4.1 ("Taffy 1"),
firing a salvo of five torpedoes. Fifty seconds later three explosions are heard.
After 2232, when one of the TU 77.4.1's escorts reports contact with a
submarine, the escort carriers commence a 90-degree emergency turn. Immediately
thereafter two torpedo wakes straddle USS PETROF BAY (CVE-80). USS COOLBAUGH
(DE-217) counterattacks I-56 and Morinaga dives to 460 feet. As a result of
attack several small leaks emerge. Cdr Stuart T. Hotchkiss claims a sinking at
When I-56 surfaces after the attack, a teardrop-shaped Mk.9 depth-charge
is recovered from her afterdeck. Elated, Morinaga reports one carrier sunk. As
I-56 has only three torpedoes left, including one that is defective, she is
ordered to return to base.
4 November 1944:
I-56 arrives at Kure. LtCdr Morinaga is credited with
sinking one carrier, one destroyer and three transports. I-56 continues
conversion to carry four "kaiten" human torpedoes.
10 November 1944:
Admiralty Islands. Ammunition ship USS MOUNT HOOD
(AE-11) explodes in Seeadler Harbor, Manus. Later, "Tokyo Rose" in one of her
broadcasts credits Japanese midget submarines with her "sinking". As a result,
ASW measures around Manus Island are stepped up.
12 November 1944:
Start of kaiten launch drills.
2 December 1944:
A special conference of more than 200 staff officers
and specialists is held aboard the Sixth Fleet's flagship, TSUKUSHI MARU to
evaluate Operation "Kikusui" (Floating Chrysanthemum) - the first kaiten mission
to Ulithi. The staff considers reports and post-attack photo-reconnaissance and
concludes erroneously three aircraft carriers and two battleships were sunk in
21 December 1944: The Second Kaiten Mission:
The plan calls for the
"Kongo" (steel) group: I-56, I-36, I-47, I-48, I-53 and I-58 to attack the
Americans at five different points. Departs Kure for Otsujima base to embark the
22 December 1944:
At 1300, departs Otsujima to attack anchored enemy
shipping in the Bismarck Sea at Manus, Admiralty Islands on 11 January, 1945.
Later, the attack time is changed to the dawn of 12 January.
6 January 1945:
Manus, Admiralty Islands. A Japanese reconnaissance
plane reports six cruisers and 28 transports in Seeadler Harbor.
10 January 1945:
60 miles W of Manus. While trying to take a fix to
establish her location, I-56 is spotted by enemy ASW forces and chased for an
11 January 1945:
At 2300 I-56 surfaces 50 miles N of Seeadler to
charge her batteries prior to run-in. When arriving 35 miles N of the harbor,
I-56's radar detector spots an approaching aircraft and the submarine dives.
Soon thereafter, the sonarman reports the presence of several ships searching
the area. LtCdr Morinaga decides to abort the attack and retires northwards.
12 January 1945:
After sundown, I-56 attempts another surfaced run-in
from a position 60 miles N of Seeadler. Forty miles away from the target a
radar-equipped aircraft is spotted. Five minutes later I-56's radar detects an
approaching ship. Her radioman monitoring enemy frequencies reports overhearing
an English order to launch "more aircraft". The submarine floods down partially
and continues the approach.
13 January 1945:
At 1902, I-56 is attacked by ASW aircraft in
the same area. At 0230, Morinaga orders I-56 to submerge. Soon thereafter the
propeller noises of several ships are heard from ahead. Morinaga decides to
abort the attack. In the evening, I-56 receives an order from the Sixth Fleet HQ
to undertake a last attempt in the morning of 14 January and then to return to
14 January 1945:
55 miles W of Manus. At 0310, during her second
attempt to reach the launch area, I-56 is again attacked by ASW aircraft.
18 January 1945:
I-56 is ordered to return with her "kaitens" aboard as
a test of their long term duration and reliability.
1 February 1945:
LtCdr (Cdr, posthumously) Masada Keiji (62)(former CO
of I-366) is appointed the CO.
3 February 1945:
Returns to Otsujima, where all "kaitens" are
disembarked, then proceeds to Kure. During a refit two cradles for the human
torpedoes are added to the foredeck.
29 February 1945: American Operation "Brewer" - The Invasion of the
Vice Admiral (later Admiral) Thomas C. Kinkaid's (former
CO of INDIANAPOLIS (CA-35) Seventh Amphibious Force lands the 1st Cavalry
Division of LtGen (later General) Walter Krueger's Sixth Army that captures Los
Negros and Manus Islands from Colonel Ezaki Yoshio's defenders.
26 March 1945: The Invasion of the Kerama Islands, Ryukyus:
(later General) Andrew D. Bruce's 77th Infantry "Statue of Liberty" Division
lands on the Keramas and by 29 March captures advance bases and anchorages for
the invasion of nearby Okinawa.
31 March 1945:
I-56 is assigned to the "Tatara" Unit with I-44, I-47
and I-58, each carrying six "kaitens". Departs Otsushima for the area NE of
1 April 1945: American Operation "Iceberg" - The Invasion of
Vice Admiral (later Admiral) Raymond A. Spruance's (former CO of
MISSISSIPPI, BB-41) Fifth Fleet, including more than 40 aircraft carriers, 18
battleships, 200 destroyers and over 1,000 support ships surround Okinawa. LtGen
Simon B. Buckner Jr's Tenth Army (7th, 77th, 96th Infantry and 1st, 6th Marine
divisions), makes amphibious landings and eventually takes the island from LtGen
Ushijima Mitsuru's 32nd Army defenders.
17 April 1945:
E of Okinawa. At 2305, radar aboard Task Force 58's
battleship USS MISSOURI (BB-63) detects a submarine 12 miles from her formation.
MISSOURI's report sets off a hunter-killer operation by USS BATAAN (CVE-29) and
several destroyers. Cdr A. T. Hathaway's HEERMAN (DD-532) makes radar contact
and Cdr S. C. Small's UHLMANN (DD-687) attacks with depth charges.
18 April 1945:
160 miles E of Okinawa. In the morning, the submarine
is repeatedly depth-charged by two aircraft from BATAAN in a combined attack
with Cdr J. D. Collet's USS COLLET (DD-730), Cdr F. D. Michael's McCORD (DD-534)
and Cdr W. S. Maddox's MERTZ (DD-691). After several hours, the submarine -
arguably I-56 - is sunk at 26-42N, 130-38E. 
2 May 1945:
Presumed lost in the Okinawa area with all 116 crewmen
plus six "kaiten" pilots.
10 June 1945:
Removed from the Navy List.
 I-56's conventional torpedoes were fitted with magnetic
exploders. Author and historian Kimata Jiro speculates that these may have
caused premature explosions.
 Several authors credit I-56 with a torpedo hit on USS SANTEE (CVE-29)
off Samar, despite differences in both time and location.
 Most Japanese historians agree that I-56 was sunk by USS HUDSON
(DD-475) on 5 April 1945, while Western sources credit HUDSON with sinking RO-49 at
that time and place. While several sources credit I-56 with sinking Cdr J.F.
Walling's USS SNOOK (SS-279) sometime after 8 April, this is not confirmed by
any Japanese sources.
Thanks go to Dr. Higuchi Tatsuhiro of Japan.
– Bob Hackett and Sander Kingsepp.
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