SENSUIKAN!

2 November 1943:
75 North American B-25 "Mitchell" medium-bombers of the Fifth Air Force’s 3rd, 38th and 345th Bomb Groups, escorted by 70 Lockheed P-38 "Lightnings", attack Rabaul’s airfields and harbor. Three destroyers and eight merchant vessels are sunk or damaged. HOKUYO MARU is damaged in the low level air attacks, but the tow had been slipped and the tokugata unkato midget supply submarine is probably berthed in the inner portion of Simpson Harbor. [6]

USAAF Raid on Rabaul (Naval Historical Center)

3 November 1943:
The future CO of the Rabaul midget submarine detachment, Lt Kado Yoshimi (former CO of midget HA-22), with two midget submarine pilots and four technical personnel depart Tateyama via Truk for Rabaul on an unidentified ship and arrive safely later in November.

17 November 1943:
Truk. At 0700, YAMABATO MARU, towing a tokugata unkato midget supply submarine, departs Saeki for Palau in convoy No. 708 consisting of TOKOKAWA, ALASKA, PACIFIC, TAIKO, KAYO, KIBI and TAIEI MARUs escorted by patrol boat No. 31 and auxiliary submarine-chasers AOI MARU and TOKUHO MARU No. 10. [1] [2]

19 November 1943:
Convoy SO-(unknown) departs Palau consisting of TASMANIA, HOZUGAWA, KENZAN and RYUKO MARUs escorted by submarine chasers CH-37 and CH-38. RYUKO MARU is towing a midget supply submarine. During the voyage south the convoy is plagued by submarine attacks.

25 November 1943:
At 1025, KENZAN MARU is torpedoed and sunk by LtCdr Oscar Hagberg's (USNA ’31) USS ALBACORE (SS-218) at 00-51N, 146-00E. Seven crewmen are KIA.

26 November 1943:
At 1338, YAMABATO MARU, her midget supply submarine and convoy No.708 arrive at Palau.

28 November 1943:
RYUKO MARU, her midget supply submarine and convoy SO-(unknown) arrive at Rabaul.

10 December 1943:
Truk. At 1230, convoy No. 1103 departs Truk for Rabaul consisting of NIKKO and KIMISHIMA MARUs and SHINSEI MARU No. 18 escorted by minesweepers W-21, W-22 and auxiliary submarine-chaser CHa-48. NIKKO MARU is towing an unidentified midget submarine and KIMISHIMA MARU is towing a midget supply submarine. [1] [2]

15 December 1943:
At 0810, SHINSEI MARU No. 18 that suffered navigational troubles a few days earlier leaves the convoy with W-22 and CHa-48 and heads for Kavieng, New Ireland. At 1210, the same day, the rest of the convoy is attacked by American aircraft, but incurs no damage.

16 December, 1943:
At 1336, the remainder of convoy No. 1103, including the midget submarine and the tokugata unkato midget supply submarine, arrive at Rabaul.

Early January 1944:
Tokuyama, Western Inland Sea. YAMATSURU MARU loads aviation fuel at the depot for delivery to Rabaul. She also carries ammunition and tows an unidentified midget submarine. [1]

2 January 1944:
Transport NEIKAI MARU departs Kure towing midget submarine HA-49, the first of the Rabaul Detachment's midget submarines.

7 January 1944:
At 0600, NEIKAI MARU departs Saeki for Palau towing HA-49 in convoy No. 0-007 with TOKO, KOFUKU, MANSHU and KENNICHI MARUs escorted by destroyer SHIRANUHI, torpedo boat HATO and auxiliary minesweepers TAMA MARU No. 7 and TAKUNAN MARU No. 3. [3]

11 January 1944:
Convoy 0-105 departs Saeki for Rabaul via Palau consisting of YAMATSURU, TARUSHIMA, ERIE, DENMARK and NARITA MARUs escorted by minesweeper W-18, and auxiliary minesweeper TAMA MARU. YAMATSURU and TARUSHIMA MARUs are towing unidentified midget submarines. In addition, YAMATSURU MARU carries the midget submarines' crews and technical personnel.

About 1230, ERIE MARU is torpedoed in hold No. 2 by LtCdr Charleton L. Murphy’s (USNA ’32) old USS STURGEON (SS-187) at 32-31N, 132-34E. At 1417, ERIE MARU lists over and sinks. 200 of about 2500 soldiers of two Infantry Battalions, a tank unit and a AA unit are KIA.The escorts counter-attack and drop 51 depth-charges. STURGEON incurs slight damage, but escapes. The convoy returns to port.

13 January 1944:
Saeki. At 0200, the convoy again sets out for Palau.

14 January 1944:
155 miles SE of Tanega-Jima. At 2025, YAMATSURU MARU is attacked by LtCdr (later Cdr) Royce L. Gross’ (USNA ’30) USS SEAWOLF (SS-197) at 28-25N, 133-30E. The oiler, that has just discontinued zigzagging, is hit by a torpedo in her No. 2 hold. There is a heavy explosion followed by great fires. YAMATSURU MARU’s cargo of aviation fuel catches fire and begins to cascade into the sea. Another torpedo strikes her between the engine room and No. 3 hold. YAMATSURU MARU lists to port and sinks within a few minutes taking down the midget submarine. 30 crewmen, two gunners and four passengers are KIA.

16 January 1944:
At 1430, NEIKAI MARU and convoy No. 0-007 arrive safely at Palau.

Philippine Sea. At 1806, that same day, LtCdr (later Cdr) Albert C. Burrow's (USNA ’28) USS WHALE (SS-239) torpedoes and sinks DENMARK MARU. 1,633 soldiers of the 14th Infantry Division, 31 crewmen, and 20 gunners are KIA. At 2250, LtCdr Gross’ SEAWOLF damages TARUSHIMA MARU by gunfire at 23-00N, 135-00E.

17 January 1944:
LtCdr Burrow's WHALE torpedoes and finishes off damaged TARUSHIMA MARU at 22-50N, 135-40E. She sinks with her midget in tow. 613 troops and 20 crewmen are KIA.

USS WHALE (U.S. Navy)

19 January 1944:
NEIKAI MARU departs Palau for Rabaul in convoy SO-903 with NIPPONKAI MARU and TAKATORI MARU No. 2 escorted by subchasers CH-17 and CH-18.

26 January 1944:
NEIKAI MARU arrives at Rabaul with midget submarine HA-49.

Simpson Harbor, Rabaul (U.S. Air Force)

E 27 January 1944:
NEIKAI MARU departs Rabaul again towing HA-49.

28 January 1944:
S of Kavieng, New Ireland. 13th Air Force B-24 “Liberator” heavy bombers and USN PBY “Catalina” patrol planes bomb NEIKAI MARU. She sinks 75 miles S of Queen Charlotte Island, Bismarcks and takes down midget submarine HA-49.

12 February 1944:
5,461-ton freighter SANKO MARU departs Palau for Rabaul in convoy SO-903 towing two unidentified midget submarines, escorted by subchaser CH-39. The ETA at Rabaul is 16 February.

16 February 1944:
Off Three Island Harbor, New Hanover. Convoy SO-903 is attacked by nine Fifth Air Force B-25 "Mitchell" medium-bombers of the 500th 'Rough Raiders' Bomb Squadron of the 345 Bomb Group that bomb, strafe and sink SANKO MARU. CH-39 is run aground on a nearby reef. The strafers also damage a midget submarine. [4]

That same afternoon, B-25s of the 499th 'Bats Outta Hell' Bomb Squadron of the 345 Bomb Group arrive at the scene and find CH-39 sunk by the stern on a reef and abandoned. The 499th Bomb Squadron finishes her off with thirteen bombs that explode her magazine and boiler and reduce CH-39 to a shattered hulk. They also bomb and strafe a midget submarine on the surface and claim a sinking.

17 February 1944:
B-25s of the 500th Bomb Squadron return to the scene again and find the other midget submarine on the surface. They bomb and strafe the midget submarine and claim a sinking. [5][6]

Type C Midget Submarine under attack off New Hanover, Bismarcks (Scanned from L. Hickey's "Warpath Across the Pacific")

28 October 2011:
Rabaul, Papua New Guinea. Australian minehunter HMAS GASCOYNE, taking part with New Zealand warships in Operation RENDER SAFE explosive ordnance disposal (EOD) in Rabaul from 18 Oct to 4 Nov '11, takes images of the wreck of a submarine 55 meters below the surface in Simpson Harbor. The 20-metre (66-feet) long submarine is partially buried in the harbor floor but remains upright. [7]

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Authors' Notes:
[1] HA-53, the last Type A midget submarine, was completed as the Type B prototype. Later, HA-49 through HA-52 were rebuilt as B Types. All five were sent to Rabaul, towed by merchants, but HA-49 and others were lost in transit. The 46-ton midgets were towed because they were too heavy to be handled by the ships' derricks.

[2] A Tokugata Unkato, also called a "pipe", was a partially completed Type A midget submarine converted into an underwater special cargo carrier. Two sections of a Type A were used together with a torpedo engine and a nose cap. It is doubtful whether any completed Type A's were used for this purpose. Type A Tokugata Unkato "pipe" at Rabaul, postwar

[3] The code name "Ko-Hyoteki' means A-Target. Until late in the war, many Japanese thought the midgets were just that, target ships.

[4] The midget submarine may have been HA-23. Some sources say the midget had just been taken off a mother submarine. It was to be provisioned, then put back on the mother sub to be deployed. Postwar, divers find the midget's two counter-rotating props still tied together and the sub's tie-down tackle still attached.

[5] Japanese sources claim the midget submarine's crew scuttled her after the B-25 attacks.

[6] In 1987, divers from MV TELITA are exploring the wreck of a sunken WW2 armed freighter off Three Islands Harbor, N of New Hanover Island. The freighter is lying on its starboard side covered in sea fans and soft corals in 22 m of water. One of the TELITA divers swims out from the wreck – straight into a Japanese midget submarine. The submarine is intact and sits upright only 50m from the freighter’s main masts. Salvagers had come and gone, but never suspected it was there. TELITA’s divers inspect the periscope, the twin counter rotating propellers and the empty twin torpedo tubes and open the hatch, which is not locked down. The slimmest diver is rigged with a line, torch and long hose and sent in. She gets to the bottom of the ladder and can see the sub is empty.

Midget Submarine sunk off New Hanover

Port Bow and Conning Tower

Starboard Bow & Empty TTs and Stern View

(Conning Tower Photo by Howard Sawyer, all others by Kevin Denlay)

[7] Midget HA-53 was at Rabaul at war's end. HA-53's source of transportation to Rabaul is unknown. on 17 Jan '46, she was raised by Australian Commonwealth Marine Salvage Board salvage ship CALEDONIAN SALVOR with help from the midget's former crew and handed over to the NOIC, Rabaul. Thereafter, she was allowed to deteriorate and finally scuttled in deep water. She may be the submarine that George Tyres found in 400 foot of water near the Keifuku Maru. Later, wreck not found again due to severe seismic underwater activities.

Japanese prisoners assisting in raising HA-53 in Simpson Harbor postwar

Thanks go to Peter Cundall and to Kevin Denlay of Australia and Erich Muehlthaler of Germany for additional info on HA-53.

Special thanks for the photos of the Kavieng midget submarine go to photojournalist/divers Howard E. Sawyer of the United Kingdom and Kevin Denlay of Australia. Thanks also go to Mr. Denlay for info on the 1987 find of the midget submarine and to Bob Haldstead, ex-owner off MV TELITA and diver Kevin Baldwin who found the midget submarine.

-Bob Hackett and Sander Kingsepp

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