Submarine Base Pearl Harbor – Buried Secrets

Buried Secrets

One of my favorite submarine reference books is called “United States Submarine Operations in World War II” written by Theodore Roscoe in conjunction with the Bureau of Naval Personnel and published by the United States Naval Institute.

Reading through the book is like a looking through a periscope to the past. The people who wrote the book actually lived through the times they recorded, and they inject small items that add flavor to their stories. One small item I found this morning while preparing for the day was a note about the fate of a Japanese mini submarine. It struck me as something unusual since I have lived and served at the Pearl Harbor Submarine base a number of times in my short career.

From the book:

“The midget submarine sunk by Curtis was raised form the mud and found to be wrecked beyond useful examination. At the Submarine Base a new pier was under construction. Fill-in material was needed, and the midget submarine’s hull made fitting residue for the excavation. A military funeral ceremony preceded the burial. Then the battered little boat – a coffin for its two-man crew – was cemented into the foundation of the Submarine Base Pier.”

Wait, what??? A Japanese mini submarine was buried into a submarine base pier?

As a submariner, I had heard about the stories of the mini submarines that attacked Pearl Harbor. One of the captured boats is on display at Sub School and I was amazed at how small yet potentially destructive the boats were.

As an amateur Pearl Harbor historian, I have studied the attacks that should have warned the Navy of the larger attack with great interest. So, I have a lot of technical and historic background about the use of the boats in general. 

I have also walked nearly every foot of every pier at Subbase Pearl. Not an exaggeration at all. As a submarine Auxiliaryman on board the USS San Francisco and a crew member on other crews, I had to walk the piers to gather supplies, repair parts, general travel, attend briefings and many other reasons. There are not many areas on Subbase that I have not been fairly intimate with. But I had never heard this story until today.

When this happens, I do what I always do. A little research. Within a short time, I found this page:

One of the stories from the page concerned that very submarine.

From: The Lost Submarines of Pearl Harbor:

“At 8:30, inside the harbor, the minesweeper USS Zane (DMS-14) spotted what it reported as a “strange submarine” 200 yards aft of the moored USS Medusa (AR-1); Zane’s commanding officer ordered the ship’s No. 4 gun loaded and prepared to shoot at it, but the gun would not bear, and the nearby USS Perry (DMS-17) instead opened up with its gun. Medusa, meanwhile, had opened up with its antiaircraft guns at incoming Japanese planes. As the ship’s commanding officer noted in his after action report, his crew spotted the submarine near them, bearing some 1,000 yards off Medusa’s starboard quarter and about 500 yards astern of the seaplane tender USS Curtiss (AV-4).

“Curtiss’ commanding officer reported that his ship opened up on the submarine at 8:36 from a distance of 700 yards. The first shots missed the periscope, but as the submarine surfaced at 8:40, and the conning tower was visible, as well as part of the bow, Curtiss fired twice, reporting they hit the conning tower twice as the submarine fired one torpedo up the North Channel toward the oncoming destroyer USS Monaghan (DD-354).

“Monaghan’s commanding officer, in his after action report, explained that as his destroyer approached the scene, he and his bridge crew spotted the conning tower of the submarine 200 to 300 yards off the starboard quarter of Curtiss, and that “vigorous fire” from Curtiss and USS Tangier (AV-8) was directed at it. The ship’s captain, W.P. Burford, ordered all engines ahead at flank speed and headed straight for the submarine to ram it, and at 8:43, the destroyer rammed and passed over the submarine while dropping two depth charges. A minute later, both charges exploded aft of Monaghan, and the submarine disappeared. Another of the kō-hyōteki had been destroyed.


“The position of the submarine sunk by Monaghan was charted and Navy divers rigged it for recovery within a few weeks of the attack. A heavy lift crane and barge lifted the submarine from the bottom and placed it on a barge for inspection on December 21. Navy explosive ordnance disposal experts boarded the barge and found “the upper part of the front end (the torpedo tube section) was completely gone. There was nothing left of the tubes or their torpedoes. Below the tubes the hull seemed to have been blown outwards to where it was almost flat.”

“The torpedoes, they surmised, had exploded in their tubes, “destroying the upper forward section of the midget submarine hull.” The examination noted other damage, including ramming damage to the aft hull; “it appeared that the sub had been rolled completely over and the rear end of the boat had been bent badly out of line. Overall the body of the boat showed the wrinkles and indentations typical of exposure to heavy explosions underwater.” The conning tower “clearly showed the path of a five-inch projectile completely through the conning tower.” With nothing to disarm, the EOD team left and the barge was moved to the sub base, where construction of a new pier provided a burial site for the craft and crew. Marine Cornelius Smith, Jr., visiting the base, saw the submarine there, and commented that “the conning tower is tiny, with room enough for one man to steer the craft. He’s still in there. One of our ships rammed him, broadside, and he’s caught, dead, with his legs hanging out; I guess they’ll have to cut him free with a blowtorch. I suppose the torpedoman inside is dead, too. “

“After some items were recovered from the craft, including the still intact figure-eight torpedo tube guards, the crane barge “dumped the wreckage along the back edge of the pier where they were filling in to level the shoreward edge of the pier” after the two dead crew members were removed and buried in a nearby cemetery. In March 1947, a Japanese naval lieutenant’s shoulder patch was repatriated to Japan by the U.S. Navy and was said to have come from the dead submarine commander. The insignia suggests to the Japanese that this craft therefore was that of Lt. Naoji Iwasa, commander of the Special Attack Flotilla and whose midget was launched from submarine f I-22. That midget was crewed by Iwasa and Petty Officer 1st Class Naokichi Sasaki. The patch is now preserved at Yasukuni Shrine. The Monaghan midget resurfaced briefly in 1952 when workers improving the quay wall at the sub base hit the buried midget with a dragline while excavating landfill to drive new sheet piles. After digging a deeper trench alongside the exposed hull, they rolled the boat over and reburied it to clear the work area.”

I was at Subbase Pearl in the early seventies, the early eighties and part of the late eighties into 1990. I am not aware of what part of the base housed the boat. It would be interesting to know where exactly it ended up. I also find it interesting that there are two different versions of what happened to the crew. The book I referenced was written just as the war was over. The NOAA article was written much later. Were the Japanese sailors still inside when the boat was buried?

Mister Mac


Update January 17, 2021

From the Navy Heritage Center Web Site regarding the disposition of the Japanese Mini subs:
Of the five Japanese midget submarines, one definitely made it into the harbor, and a second probably did as well.  The midget launched from I-19 got hopelessly lost and eventually went aground on the east side of Oahu; one of the two crew was captured and became the first Japanese POW of the war; this submarine is now on display at the Museum of the Pacific War in Fredericksburg, Texas.  The midget launched by I-18 was damaged by depth charges and abandoned by its crew; it was recovered from Keehi Lagoon (with its two torpedoes) in 1960 and returned to Japan where it is on display at the Eta Jima naval academy.  The midget launched from I-20 was sunk by the Ward.  The midget launched by I-22 made it into the harbor where it was fired upon by several ships before being rammed, depth charged and sunk by the USS Monaghan (DD-345) the duty destroyer that had gotten underway in reaction to Ward’s report; both torpedoes fired by the midget missed; the remains of the submarine were used as land-fill, and a later attempt to recover the crew abandoned due to toxic residue.

5 thoughts on “Submarine Base Pearl Harbor – Buried Secrets

    1. Lots of suppositions. Lots of folks remember reading about it but so far still waiting for the definitive answers. Where was it actually buried and were the sailors still in it at the time?

      1. I find it difficult to believe that, even then and in the heat of the moment, that the American sailors would not pay the proper respects accordingly…
        I could be wrong, though.

  1. I remember as a small boy in 1951/52 era a Japanese midget on display at the Pearl Harbor Subbase. Infact I and two friends were climbing on it and the Base MP’s came along an told us to get off and go home. Where did that Sub end up?

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