SENSUIKAN!

© 2001-2013 Bob Hackett & Sander Kingsepp
Revision 6

12 June 1925:
Laid down at Kawasaki Kobe Yard as I-23 (ex-Submarine No. 50).

19 March 1927:
Launched.

1 December 1927:
LtCdr (Vice Admiral, posthumously) Tsujimura Takehisa (42)(former CO of RO-20) is appointed the Chief Equipping Officer (CEO).

28 April 1928:
Kobe. Completed at Kawasaki's shipyard as I-23 and attached to Yokosuka Naval District. LtCdr Tsujimura is the Commanding Officer.

10 March 1929:
LtCdr (Rear Admiral, posthumously) Ito Jotaro (42)(former CO of RO-63) is appointed the CO.

9 June 1930:
LtCdr (Rear Admiral, posthumously) Oda Tamekiyo (43)(former CO of RO-51) is appointed the CO.

1 December 1931:
LtCdr (Rear Admiral, posthumously) Otake Toshio (45)(former CO of RO-63) is appointed the CO.

15 November 1933:
LtCdr (later Captain) Oyama Toyojiro (47)(former CO of RO-59) is appointed the CO.

15 November 1934:
LtCdr (Captain, posthumously) Katsumi Motoi (49)(former torpedo officer of I-1) is appointed the CO.

28 February 1935:
LtCdr (later Captain) Nagai Takeo (47)(former CO of RO-25) is appointed the CO of I-23 and I-24 as an additional duty.

25 May 1935:
LtCdr (Cdr, posthumously) Hattori Kunio (47)(former CO of I-62) is appointed the CO of I-23 and I-24 as an additional duty.

3 July 1935:
LtCdr (later Captain) Nishino Kozo (48)(former CO of RO-58) is appointed the CO.

25 November 1935:
Placed in reserve at Kure for the main ballast tanks reinforcement.

26 December 1935:
LtCdr (later Captain) Mizohata Sadaichi (46)(former CO of I-4) is appointed the CO.

1 December 1936:
LtCdr (Rear Admiral, posthumously) Ankyu Eitaro (50)(former torpedo officer of I-57) is appointed the CO.

7 July 1937: The Marco Polo Bridge (The "First China Incident"):
Hun River, Lugouqiao, China. Japanese troops on night maneuvers fire blank cartridges. Nearby Chinese troops fire back, but do not cause injuries. At morning roll call, the Japanese discover a soldier missing and assume the Chinese captured him. They demand entry to a Peking suburb to look for the soldier. The Chinese refuse. The Japanese then shell the city and an undeclared war on China begins.

September 1937:
SubDiv 9 with I-23 and I-24 joins the naval blockade over the southern Chinese coast.

19 March 1938:
LtCdr (Captain, posthumously) Izu Juichi (51)(former CO of I-65) is appointed the CO.

1 June 1938:
I-23 is renumbered I-123.

15 November 1938:
LtCdr (later Captain) Yamada Kaoru (50)(former CO of I-65) is appointed the CO.

20 November 1939:
LtCdr (later Captain) Tonozuka Kinzo (50)(former CO of I-55) is appointed the CO.

Mid-1940:
The entire I-121 class is converted to carry 15 tons of aviation fuel for Kawanishi H6K Type 97 "Mavis" flying boats.

5 November 1940:
LtCdr (later Captain) Maruyama Hanzo (52)(former SubRon 3 staff officer) is appointed the CO.

1 May 1941:
I-123 is based at Kure with I-124 in Cdr Endo Keiyu's (46)(former CO of I-2 and others) SubDiv 9 of Rear Admiral Kono Chimaki's SubRon 6, Third Fleet.

2 August 1941:
I-123 is again designated the flagship of SubDiv 9.

5 September 1941:
LtCdr (Cdr, posthumously) Ueno Toshitake (56)(former torpedo officer of I-9) is appointed the CO.

November 1941:
I-123 is in the Third Fleet under Rear Admiral Kono Chimaki's SubRon 6 in Cdr Endo Keiyu's SubDiv 9. LtCdr Ueno Toshitake is I-123's Commanding Officer. Departs Yokosuka for Samah, Hainan Island, China.

1 December 1941:
I-123 and I-124 depart Samah for the Philippines. Attached to the Philippines Seizure Force with I-124.

2 December 1941:
The coded signal "Niitakayama nobore (Climb Mt. Niitaka) 1208" is received from the Combined Fleet. It signifies that hostilities will commence on 8 December (Japan time). Mt. Niitaka, located in Formosa (now Taiwan), is then the highest point in the Japanese Empire.

6 December 1941: Operation "M":
Vice Admiral Takahashi Ibo's (36)(former CO of KIRISHIMA) Third Fleet, Southern Force, Philippines Seizure Force departs Palau. On that day at 0420, I-123 suffers a foreplane failure, preventing her from diving. The crippled submarine proceeds to Balabac Strait on the 7 December to lay a barrage of 40 Type 88 Mk. 1 mines there. She heads for her base at Camranh Bay, Occupied French Indochina for repairs thereafter. [1]

9 December 1941:
Arrives at Camranh.

11 December 1941:
Vice Admiral Takahashi's force makes invasion landings at Legaspi, then Davao (19-20 December) and Jolo (24 December).

15 December 1941:
Departs Camranh for the Java Sea on her second war patrol.

18 December 1941:
Celebes Sea. At 2053, I-123 attacks a transport, but misses.

23 December 1941:
Lays mines at the northern entrance of Surabaya harbor, Java.

22 December 1941:
LtCdr Ueno reports the sighting of two carriers in the Java Sea.

23 December 1941:
Between 0246 and 0526, lays mines at the northern entrance of Surabaya harbor, Java.

26 December 1941:
Reassigned to Submarine Group A with I-121 through -124.

31 December 1941:
Arrives at Davao on Mindanao, Philippines. There she is joined by SubRon 6's flagship, 6,600-ton submarine tender CHOGEI and I-121 and I-124.

10 January 1942:
Departs Davao on her third war patrol for Beagle Gulf-Van Diemen Gulf area, Australia.

18 January 1942:
Arrives off the western entrance of Clarence Strait.

20 January 1942:
Beagle Gulf, 40 miles W of Darwin. LtCdr Ueno sights a Darwin-bound Allied auxiliary transport escorted by two destroyers. I-123 commences an approach and after 0520 fires a spread a four Type 89 successive torpedoes at the transport.

At 0526 DesDiv 58's destroyers USS ALDEN (DD-211) and EDSALL are escorting the 5,375-ton oiler USS TRINITY (AO-13) to Darwin, when TRINITY reports that three torpedoes were fired at her at 12-05.5S, 130-05.6E. At 0541 ALDEN carries out a brief depth charge attack and finally loses the contact.

The soundman of I-123 reports that the transport was hit by one torpedo hit but did not sink. Neither of ALDEN's depth charges causes any damage to the submarine.

After 2046 I-123 lays 30 mines off Cape Don on the Coburg Peninsula, Dundas Strait.

3 February 1942:
Arrives at Davao on Mindano. All three submarines are serviced by tender CHOGEI.

19 February 1942:
Departs Davao on her fourth war patrol to lay a minefield to the Torres Strait.

25 February 1942:
Arrives at her patrol sector in the Torres Strait, replacing I-122, now en route to Staring Bay, Celebes. That night, I-123 lays 40 mines in the area 80 miles W of Booby Island.

9 March 1942:
Arrives at Staring Bay, Celebes without contacting any enemy ships.

14 March 1942:
Departs Staring Bay for Yokosuka. 25 March 1942:
Arrives at Yokosuka for overhaul and repairs.

7 May 1942: Operation "K-2": Flying Boat Reconnaissance of Pearl Harbor:
I-123 is in SubRon 3's SubDiv 13 with I-121 and I-122 in Vice Admiral Komatsu's Advance Expeditionary Force (Sixth Fleet). SubDiv 13 is assigned to carry gas and oil to Lisianski Island and to French Frigate Shoal, Hawaii. The K-2 operation plan calls for two H8K "Emily" flying boats to refuel at the Shoals and then reconnoiter the naval base at Pearl Harbor prior to the Midway Invasion.

I-123 departs Yokosuka for Kwajalein.

17 May 1942:
Arrives at Kwajalein.

19 May 1942:
Departs Kwajalein for the French Frigate Shoals to participate in Operation K-2.

29 May 1942:
I-123 arrives at the Shoals. LtCdr Ueno observes two seaplane tenders in the lagoon as well as patrol planes in the area. That night, I-123 surfaces and radios his sightings to the Sixth Fleet at Kwajalein. The Pearl Harbor reconnaissance is postponed by one day.

31 May 1942:
LtCdr Ueno observes more vessels in the lagoon and witnesses the landing of several seaplanes. After his report to the Sixth Fleet, Operation K-2 is canceled. I-123 and I-121 receive the order to continue to patrol in the vicinity of the Shoals.

4 June 1942:
I-123, I-121 and I-122 begin patrolling off the Hawaiian Islands, then return to Yokosuka.

25 June 1942:
Arrives at Kwajalein, then proceeds to Yokosuka.

30 June 1942:
LtCdr (Cdr, posthumously) Nakai Makoto (58)(former CO of RO-59) is appointed the CO.

14 July 1942:
Captain Miyazaki Takeji's SubDiv 13 is reassigned to SubRon 7, Eighth Fleet.

26 July 1942:
Departs Yokosuka for Truk.

2 August 1942:
Arrives at Truk.

7 August 1942: American Operation "Watchtower" - The Invasion of Guadalcanal, British Solomon Islands:
Rear Admiral (later Admiral) Richmond K. Turner's (USNA '04) Amphibious Task Force 62, covered by Vice Admiral (later Admiral) Frank J. Fletcher's (USNA '06) Task Force 61 and Rear Admiral (later Admiral) John S. McCain's (USNA '06) Task Force 63's land-based aircraft, lands Maj Gen (later Gen/Commandant) Alexander A. Vandegrift's 1st Marine Division on Florida, Tulagi, Gavutu, Tanambogo and Guadalcanal opening a seven-month campaign to take the island.

Departs Truk on her fifth war patrol to patrol off Indispensable Strait; later redirected to reconnoiter Lunga anchorage, Guadalcanal.

11 August 1943:
Arrives off Lunga Point, Guadalcanal.

12 August 1942:
After 1100, I-123 surfaces N of Lunga Point and fires 14 shells at the nearest Marine unit from 700 yds distance. I-123 is likewise taken under fire from ashore, but dives without receiving any damage.

Later that day she receives an order to contact IJA troops at Taivu Point, Guadalcanal.

16 August 1942:
Attempts to contact the troops on Taivu Point without any results.

23 August 1942: Operation "KA": The Destruction of the American Fleet and the Recapture of Guadalcanal:
Vice Admiral (later Admiral) Kondo Nobutake's (35)(former CO of KONGO) Second Fleet, Advanced Force: CruDiv's 4 and 5, CarDiv 11's seaplane tender CHITOSE, DesRon 4's light cruiser YURA and nine destroyers arrive off Truk from Japan. Kondo joins Vice Admiral Nagumo Chuichi's Third Fleet, Main Body's CarDiv 1's SHOKAKU and ZUIKAKU, CarDiv 2's RYUJO, BatDiv 11, CruDiv 7 and 8 and Desron 10's light cruiser NAGARA and destroyers for operations in the Solomons.

24 August 1942: The Battle of the Eastern Solomons:
Vice Admiral Frank J. Fletcher's Task Force 61's USS SARATOGA (CV-3) and ENTERPRISE (CV-6) launch aircraft that find and sink light carrier RYUJO. In turn, SHOKAKU and ZUIKAKU launch aircraft that find and damage ENTERPRISE. That evening, aircraft from SARATOGA damage CHITOSE.

I-123 receives an order to deliver food to an Army coastwatcher post on Florida Island. After LtCdr Nakai fails to locate that unit, I-123 is redirected to the E of Savo Island.

29 August 1942:
At 0312 LtCdr Nakai reports that his submarine had been forced to dive at 0125 by a passing seaplane. This is the last message received from I-123.

60 miles E of Savo Island. At 0805 that morning, the lookouts on LtCdr Stephen N. Tackney's destroyer-minelayer USS GAMBLE (DM-15), headed to Guadalcanal with TU 62.2.4, spot the conning tower of a diving submarine. GAMBLE tracks I-123, using her magnetic anomaly detection system. Between 0844 and 1147 the destroyer-minelayer conducts several depth charge attacks.

Submarine RO-34 patrolling to the west of that location registers a number of explosions coming from I-123's location.

After the last attack, GAMBLE runs through a large oil slick. Her crew sees a large air bubble break the surface and later recovers broken deck planking. I-123 is sunk about 60 miles E of Savo Island at 09-21S, 160-43E.

LtCdr Nakai is promoted Cdr, posthumously.

1 September 1942:
Presumed lost with all 71 hands off Guadalcanal.

5 October 1942:
Removed from the Navy List.

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Authors' Note:
[1] A recent theory suggests that I-123's mines might have been be responsible for the loss of USS FLIER (SS-250), mined in that area in August 1944.

Thanks go to Dr. Higuchi Tatsuhiro of Japan and Steve Eckardt of Australia.

Special thanks also go to author John B. Lundstrom for sharing his research on carrier operations off Guadalcanal and to author Dr. Tom Lewis of Australia.

– Bob Hackett and Sander Kingsepp

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