Japanese submarine I-29

I-29, code-named Matsu (松, Japanese for "pine tree"), was a B1 type submarine of the Imperial Japanese Navy used during World War II on two secret missions with Germany. She was sunk while coming back from the second mission.

Type B Submarines
This was the most numerous class of Japanese submarines - almost 20 were built, of which only one (I-36) survived. These boats were fast, had a long range, and carried a seaplane, launched via a forward catapult.

The keel of I-29 was laid on 29 September 1940 at the Yokosuka Naval Yard, and she was commissioned on 27 February 1942, into the 14th submarine squadron under the command of Lieutenant Commander (later Captain) Izu Juichi (伊豆壽市).

Yanagi missions
These were missions enabled under the Axis Powers' Tripartite Pact to provide for an exchange of personnel, strategic materials and manufactured goods between Germany, Italy and Japan. Initially, cargo ships made the exchanges, but when that was no longer possible submarines were used.

Only four other submarines had attempted this trans-oceanic voyage during World War II: I-30 (April 1942), I-8 (June 1943), I-34 (October 1943) and the German submarine U-511 (August 1943). Of these, I-30 was sunk by a mine and I-34 by the British submarine Taurus. Later, the famous Japanese submarine I-52 would also share their fate.

Missions
I-29 participated in missions supporting the attack on Port Moresby in New Guinea (Operation Mo), and also in the futile search for Task Force 16, that launched the Doolittle Raid on Tokyo in April 1942.

I-29's reconnaissance of Sydney harbour on 23 May 1942 resulted in the Japanese midget submarine attack on Sydney Harbour.

First exchange
In April 1943, I-29 was tasked with a Yanagi mission. She was commanded by Captain Masao Teraoka, submarine flotilla commander — indicating the importance of the trip. She left Penang with a cargo that included two tons of gold. She met Fregattenkapitän Werner Musenberg's Type IXD-1 U-boat, U-180 on 26 April 1943 off the coast of Mozambique.

During this meeting that lasted over 12 hours due to bad weather, the two Axis submarines swapped several important passengers. U-180 transferred Netaji Subhas Chandra Bose, a leader of the Indian Independence Movement who was going from Berlin to Tokyo, and his Adjutant, Abid Hasan. I-29 in turn transferred two Japanese Navy personnel who were to study U-boat building techniques in Germany: Commander (later posthumously promoted to Rear Admiral) Emi Tetsushiro, and Lieutenant Commander (later posthumously promoted to Captain) Tomonaga Hideo (who was later connected with the German submarine U-234). Both submarines returned safely to their bases. I-29 landed her important passengers at Sabang on Weh Island, located to the north of Sumatra on 6 May 1943, instead of the Penang, to avoid detection by British spies. Bose and Hasan's transfer is the only known record of a civilian transfer between two submarines of two different navies in World War II.

Second exchange
On December 17, 1943, I-29 was dispatched on a second Yanagi mission, this time to Lorient, France under star Japanese submarine Commander Takakazu Kinashi. At Singapore she was loaded with 80 tons of raw rubber, 80 tons of tungsten, 50 tons of tin, two tons of zinc, and three tons of quinine, opium and coffee.

In spite of Allied Ultra decrypts of her mission, I-29 managed to reach Lorient 11 March 1944. On her way she was refueled twice by German vessels. Also, she had three close brushes with Allied aircraft tracking her signals. Of special note is the attack of six RAF aircraft including two Tse-tse De Havilland Mosquito F Mk. XVIII fighters equipped with 57 mm cannons from the No. 248 RAF Squadron off Cape Peñas, Bay of Biscay, at 43.66°N, -5.85°W, and the protection provided to her during the entry into Lorient by the Luftwaffe's only Long Range Maritime Fighter Unit, V Gruppe/Kampfgeschwader 40 using Ju-88s. At least one Ju-88 was shot down by British fighters over Spanish waters. The Kriegsmarine also provide an escort of two destroyers and two torpedo boats.

She left Lorient 16 April 1944 for the long voyage home with a cargo of 18 passengers, torpedo boat engines, Enigma coding machines, radar components, a Walter HWK 509A rocket engine, and Messerschmitt Me 163 & Messerschmitt Me 262 blueprints for the development of the rocket plane Mitsubishi J8M. After an uneventful trip she arrived at Singapore in 14 July 1944, disembarking her passengers, though not the cargo.

Sinking
On her way back to Kure, Japan, she was attacked at Balintang Channel, Luzon Strait near the Philippines by Commander W. D. Wilkins' "Wildcats" submarine taskforce consisting of Tilefish, Rock and Sawfish, using Ultra signal intelligence. During the evening of 26 July 1944, she was spotted by Sawfish which fired four torpedoes at her. Three hit the I-29, which sank immediately at 20.1°N, 121.55°W. Only one of her crewmen survived.

Among the dead was I-29 's Commanding Officer, Commander Takakazu Kinashi, Japan's highest-scoring submarine "ace". Earlier in the war, as skipper of I-29 's sister ship I-19, Kinashi torpedoed and sank the U.S. aircraft carrier USS Wasp and damaged both the battleship USS North Carolina and the destroyer USS O'Brien during the same attack. O'Brien later sank as a result of the torpedo damage and North Carolina was under repair at Pearl Harbor until November 16, 1942, a notable achievement that is still considered to this day to be the most effective torpedo salvo ever fired in naval history. Kinashi was honored by a rare two-rank posthumous promotion to Rear Admiral.

Additional reading

 * Miller, Vernon. Analysis of Japanese Submarine Losses to Allied Submarines in World War II, Merriam Press Original Publication, 36 pgs.
 * Boyd, Carl and Akihiko Yoshida. The Japanese Submarine Force and World War II., Annapolis: Naval Institute Press, 1995
 * Jenkins, David. Battle Surface!: Japan's Submarine War Against Australia, 1942-44. Milsons Point and London: Random House, 1992
 * Goss, Chris. Bloody Biscay: The Story of the Luftwaffe's Only Long Range Maritime Fighter Unit, V Gruppe/Kampfgeschwader 40, and its Adversaries, 1942-1944. Manchester, England: Crecy Publishing, 1997, ISBN 0-947554-62-9, 254 pgs.
 * Clay Blair" Hitler's U-Boats War The Hunted 1942-1945