© 2011 Bob Hackett
Rev 1

The Final Destruction of Japan’s Submarine Fleet

(I-402 colorized photo by Irootoko Jr)

By Bob Hackett and Derek Waller

26 July 1945:
Potsdam, Germany. The United States, United Kingdom and the Republic of China in the Potsdam Proclamation, announce their proposed terms for Japan's surrender, which include a statement that "The Japanese military forces shall be completely disarmed." At that time, the Russsians are not at war with Japan.

(Atlee, Truman and Stalin at Potsdam, 1945)

2 August 1945:
The Americans, British and Russians sign the Potsdam Agreement. Among other things, the Agreement seals the fate of the majority of Germany’s surrendered Kriegsmarine’s U-Boats. Each of the three major Allies is allowed to retain 10 U-Boats for testing and experimental purposes. The remaining 118 U-Boats on either side of the Atlantic are to be sunk in deep water before 15 February 1946.

6 September 1945:
Washington DC. President Harry S. Truman approves a document “United States Initial Post-Defeat Policy Relating to Japan” which includes statements that “Japan's ground, air and naval forces shall be disarmed and disbanded and that “naval vessels …shall be surrendered and shall be disposed of as required by the Supreme Commander” (SCAP - General of the Army Douglas MacArthur).

At the end of the war, 49 former Imperial Japanese Navy (IJN) submarines surrender afloat in the Far East. Many of these boats surrender at the IJN base at Sasebo, near Nagasaki, in the far west of Kyushu. Three ex-German U-Boats also surrender to US forces in Japan: U-511 at Maizuru and two ex-Italian U-Boats, UIT-24 and UIT-25 at Kobe. [1]

Four other ex-U-Boats surrender under the Japanese flag to the Royal Navy; two in Singapore and two in Java. The Potsdam Proclamation determined the fate of these four ex-U-Boats, but it did not specify the fate of the three ex-U-Boats in Japan.

October 1945:
Five IJN ‘super’ submarines (I-14, 1-201, I-203, I-400 and I-401) are moved from Japan to Pearl Harbor, Hawaii for test and evaluation by the USN. These are to be destroyed at the discretion of the C-in-C Pacific Fleet.

Late 1945:
Most remaining IJN submarines are moved from the ports where they surrendered to Sasebo, especially those from Kure.

February 1946:
All four ex-U-Boats are sunk/scuttled in Singapore and two in Java in accordance with the recommendations of the Tripartite Naval Commission (TNC) set up following the Potsdam Declaration in Europe to dispose of the remnants of the Nazi fleet:

3 February 1946:
I-505 (ex-U-219) is sunk south of Sunda Strait, Indonesia by Royal Netherlands Navy destroyer Hr.Ms. KORTENAER (ex-British HMS SCORPION).

15 February 1946:
Ex-U-boats, I-501 (ex-U-181) and I-502 (ex-U-862) are sunk by Royal Navy frigates HMS LOCH LOMOND and HMS LOCH GLENDHU in the Straits of Malacca, off Singapore, while I-506 (ex-U-195) is sunk by the Royal Navy’s cruiser HMS SUSSEX in the Bali Sea, east of Kangean Island.

26 March 1946:
Washington DC. At a Submarine Officers’ Conference it is reported that "orders are being issued to dispose of all Japanese submarines by sinking. Those in Japan will be sunk at once, those in Pearl Harbor when authorized by SCAP and at the discretion of CINCPAC". This statement included all surviving Japanese submarines, including those which had been incomplete or which had been decommissioned at the time of their capture, and those moved to Pearl Harbor by the USN.

The decision also includes the three ex-U-Boats that surrendered in Japan, but which had not been destroyed in accordance with the Potsdam Agreement because the USN’s CNO successfully argues they were Japanese submarines when surrendered and, therefore, outside the Agreement’s jurisdiction.

April 1946:
Tokyo. SCAP approves a plan that calls for all former Japanese Navy combatant ships larger than destroyer class to be completely scrapped. It calls for wrecked and heavily damaged ships to be sunk in deep water and to dispose of all submarines afloat.

There are five main disposal areas for the Japanese submarines to be sunk at sea. These are Maizuru Bay, Kii Suido, Iyo Nada (The Inland Sea), off Sasebo Bay, and at “Point Deep Six” off the island of Goto-Retto about 40 miles west of Nagasaki.

(Final Sortie from Sasebo)

1 April 1946: “Operation “Road’s End”:
Twenty-four IJN submarines capable of sailing under their own power and manned by skeleton Japanese crews left Sasebo and were assembled at “Point Deep Six”. There, they are sunk near the 100 fathom line, either by demolition charges or by gunfire from submarine tender USS NEREUS (AS-17) and destroyer USS EVERETT F. LARSON (DD-830). [2]

("Roads End" subs underway)

5 April 1946: Operation “Dead Duck”:
Off Sasebo Bay. Four disabled former IJN submarines are towed to sea and sunk by explosive charges. These are I-202, HA-207, HA-210 and HA-216.

16 April 1946:
I-503 (former Italian COMANDANTE ALFREDO CAPPELLINI, later German UIT-24) is sunk by the USN in the Kii Suido (Strait) between the islands of Honshu and Shikolu. She had been captured in the Mitsubishi Shipyard at Kobe, on the south coast of Honshu.

That same day, I-504 (former Italian LUIGI TORELLI, later German UIT-25 is also sunk by the USN in the Kii Suido. She had been captured in Kawasaki’s Shipyard at Kobe.

30 April 1946:
RO-500 (ex-German U-511 is sunk by the USN in the Sea of Japan in Wakasa Bay near Maizuru on the north coast of Honshu Island where she had been surrendered. The exact circumstances of the three ex-U-boats final disposal are unclear, although it seems probable that were towed to sea and scuttled with demolition charges. IJN submarines I-121 and RO-68 are also scuttled off Maizuru that same day.

(I-121, RO-68 and RO-500's final day at Maizuru)

May 1946:
Only a few former IJN submarines are left afloat and these are scuttled in the Iyo Nada (Inland Sea). They are I-155, RO-62, RO-63 and HA-205. That same month, the last operations are conducted by the USN to destroy the five IJN submarines that had undergone test and evaluation at Pearl Harbor. All are sunk off Hawaii by United States submarines:

21 May 1946:
I-203 is sunk by USS CAIMAN (SS-323).

23 May 1946:
I-201 is sunk by USS USS QUEENFISH (SS-393).

28 May 1946:
I-14 is sunk by USS BUGARA (SS-331).

31 May 1946:
I-401 is sunk by USS CABEZON (SS-334).

4 June 1946:
Finally, I-400 sunk by USS TRUMPETFISH (SS-425). [3]

I-369 is scrapped at Yokosuka Navy Yard and HA-209 is scrapped at Mitsubishi's Shipyard at Shimonoseki. HA-204, that grounded in Aburatsu Bay in October 1945, is the last submarine to go. Her hulk is scrapped in 1948.

General MacArthur’s Report records that by October 1946 all submarines (a total of 151) had been disposed of. The Report quotes a June 1949 in the Tokyo “Pacific Stars and Stripes” newspaper article dated that when the IJN disposal task was complete, “42 submarines had been scrapped and a further 104 had been sunk”. Thus, in addition to the disposal of the 49 IJN submarines which surrendered, some 100 other submarines were subject to the disposal process as outlined in the Potsdam Protocol.

It has been possible to detail where and when the 49 former IJN submarines shown above met their final end; but details are less precise concerning the 100 or so other (unseaworthy) submarines captured in Japan at the end of the war. Further, the Imperial Japanese Army (IJA) had operated a number of transport submarines and seven of these were surrendered at the end of the war.

Authors' Notes:
[1] The 49 IJN submarines that surrendered afloat were:
I-14, I-36, I-47, I-53, I-58, I-121, I-155, I-156, I-157, I-158, I-159, I-162, I-201, I-202, I-203, I-363, I-366, I-367, I-369, I-400, I-401, I-402, I-501 (U-181), I-502 (U-862), I-503 (UIT-24), I-504 (UIT-25), I-505 (U-219) and I-506 (U-195)
RO-50, RO-62, RO-63, RO-68 and RO-500 (U-511)
HA-103, HA-105, HA-106, HA-107, HA-108, HA-109, HA-111, HA-201, HA-202, HA-203, HA-204, HA-205, HA-207, HA-208, HA-209 and HA-210.

[2] The 24 IJN submarines sunk off Sasebo in Operation “Road’s End” were:
I-36, I-47, I-53, I-58, I-156, I-157, I-158, I-159, I-162, I-366, I-367, I-402, RO-50, HA-103, HA-105, HA-106, HA-107, HA-108, HA-109, HA-111, HA-201, HA-202, HA-203 and HA-208.

[3] Reportedly, I-400, I-401, I-14 and the I-200 class submarines were sunk to prevent their technology from being surrendered to the Russians.

[4] In 2004, co-author Bob Hackett worked with Parallax Film productions of Canada which produced "Sen Toku: The Search for Japan's Ghost Fleet" that aired as a Discovery Channel special that year. This search located several of the 24 former IJN submarines scuttled off Goto Retto in "Operation Road's End".

[5] On 17 March 2005, off Oahu, Hawaii, the Hawaii Undersea Research Laboratory's (HURL) deep-diving submersibles Pisces IV and V located I-401 off the coast of Kalaeloa. I-401 lies in about 870 meters (2827 feet) off the coast of Barbers Point.

[6] On 15 February 2009, off Barber's Point, Hawaii, HURL’s deep-diving submersibles Pisces IV and Pisces V located I-14 ; The wreck’s portions lies at a depth of about 800 meters. The next day, Pisces IV located I-201 nearby.

Co-author Derek Waller, Air Commodore, RAF (Ret), authored many fine articles concerning the post war surrender and destruction of German U-boats that are posted on the excellent uboat.net website.

Thanks go to Sander Kingsepp of Estonia for providing some Japanese language source data.

-Bob Hackett and Derek Waller

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