Built by 'P' Naval Armory (Ōurasaki) during 1943 as the 52nd Type A midget submarine completed, then rebuilt as as one of five Type B Midget Submarine (Tokugata Unkato): HA-49, HA-50, HA-51, HA-52 and HA-53.
Delivered to the Imperial Japanese Navy (IJN) HA-52 was assigned to Lt Nishi Hitoshi. Too heavy to be lifted aboard a merchant using their derricks, the submarines would instead be towed to Rabaul.
On October 9, 1943 departs Yokosuka towed by a merchant vessel in "convoy no. 3009B" including Hokuyo Maru, Shinyo Maru, Eiko Maru No. 2 and possibly other vessels. The convoy arrives at Truk on October 20, 1943. Departs Truk on October 23, 1943 as part of "convoy no. 1232" arriving at Rabaul on October 28, 1943.
On January 25, 1944 at 6:00pm departs Rabaul towed by Kizugawa Maru bound for Palau as part of "convoy O-510" including Hasshu Maru, Hinode Maru, Kibi Maru, Kizugawa Maru, Macassar Maru, Mito Maru, Yakumo Maru, Sanko Maru, Tasmania Maru, Yakumo Maru and Shinto Maru No. 1 escorted by destroyer Harukaze, minesweeper W-17 and Tama Maru No. 7. On February 6, 1944 arrives at Palau and this midget submarine was transfered to Sanko Maru.
On February 12, 1944 departs Palau towed by Sanko Maru as part of "Convoy SO-903" with Tatsukiku Maru, Shinto Maru No. 1 escorted by subchasers CH-22 and CH-39 and CHA-16 bound for Rabaul. Off Mussau Island, Sanko Maru towing HA-52 escorted by subchaser CH-39 detach for Kavieng.
On February 16, 1944 off Three Island Harbor on the northeast side of New
Hanover, Sanko Maru towing HA-52 escorted by CH-39 were spotted and attacked by B-25 Mitchells from the 345th Bombardment Group, 500th Bombardment Squadron that strafe and sink Sanko Maru and HA-52.
Later that afternoon, the same B-25 return and again strafe CH-39 exploding it and further strafe HA-52 claiming it as sunk.
Fate of the Crew
During the first strafing attack, Lt Nishi Hitoshi managed to escape the midget submarine and was rescued by CH-39 before it ran aground and was later sunk. He survived its sinking, swam ashore on New
Hanover and was later rescued and transported to Rabaul by March 2, 1944. At Rabaul, he was promoted to a full Lieutenant and served as 86th Guard Unit as a Butai commander. He survived the Pacific War.
This submarine sank upright on a sandy bottom at a depth of 20m, roughly 50m from Sanko Maru. During 1987, discovered by SCUBA divers from MV Telita while diving the shipwreck nearby. Divers discovered the propellers tied together and tie-down tackle attached, indicating it was sunk while being towed. The conning tower hatch was open and both torpedo tubes were empty. One diver explored inside and found the interior empty.
"Kevin Baldwin, the owner/captain of the Tiata, told me
he knows a guy who actually contacted one of the crew of the mini-sub and got
the story of what happened that day. I have seen pictures of this raid in Warpath
Across the Pacific. You can clearly see the mini-sub on the
surface next to the burning freighter, the picture taken from the
tail of the B-25 that did the bombing run. The mini-sub is sunk
in exactly the same position as seen in the photograph.
Kevin told me he saw that the props were still tied
together when he first dove on the wreck in the 1970s. I looked but
couldn't tell, but, hey, there's 60 years of growth on there. I could
barely make out one of the prop blades. The tie-down tackle is clearly
visible on the bow and stern, though."
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, this is incorrect.
Combined Fleet - Midget Submarines in the Bismarcks 1943-1944
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May 22, 2017