SENSUIKAN!

© 2001-2017 by Bob Hackett & Sander Kingsepp
Revision 3

7 June 1939:
Laid down at Kure Navy Yard as Submarine No. 143.

17 September 1940:
Launched as I-35.

31 October 1941:
LtCdr (later Cdr) Kono Masamichi (52)(former CO of I-60) is appointed the Chief Equipping Officer (CEO).

1 November 1941:
I-35 is renumbered I-30.

28 February 1942:
I-30 is completed and registered in the IJN. Attached to Kure Naval District.

10 March 1942:
Cdr (Captain, posthumously) Endo Shinobu (52)(former CO of I-121) is appointed the CO.

27 March 1942:
The German Kriegsmarine naval staff requests the IJN to launch operations against Allied convoys in the Indian Ocean.

8 April 1942:
The Japanese formally agree to dispatch submarines to the East Coast of Africa.

11 April 1942:
Departs Kure for Penang, Malaya, carrying an Aichi E14Y1 Type 0 "Glen" floatplane.

16 April 1942:
I-30 is assigned to Captain (later Rear Admiral) Ishizaki Noboru's (former CO of HYUGA) SubRon 8, in the "A" (Ko) detachment with I-10, I-16, I-18 and I-20 and their support ships, auxiliary cruisers/supply ships AIKOKU MARU and HOKOKU MARU.

Hashirajima, Hiroshima Bay. Vice Admiral Komatsu, Captain Ishizaki, their staffs and the midget submarine crews pay a courtesy call on the CINC, Combined Fleet, Admiral Yamamoto Isoroku (former CO of AKAGI) aboard his flagship, new battleship YAMATO, moored in Hiroshima Bay. At 1100, the "A" detachment departs Hashirajima via Singapore for Penang.

20 April 1942:I-30 arrives at Penang.

22 April 1942:
I-30 departs Penang with AIKOKU MARU in advance of the "A" detachment to reconnoiter selected points on the East African coast for possible attack.

25 April 1942:
I-30 refuels at sea from AIKOKU MARU.

29 April 1942:
Emperor Hirohito's (Showa) birthday. The "A" detachment departs Penang, under Captain Ishizaki in his flagship I-10, and sorties towards the coast of East Africa.

7 May 1942:
Indian Ocean. Gulf of Aden. At dawn, I-30 launches her floatplane to reconnoiter Aden.

8 May 1942:
After sundown, I-30 launches her "Glen" to reconnoiter Djibouti, French Somaliland. The floatplane is sighted and comes under fire from several warships; the mission has to be aborted.

19 May 1942:
I-30 launches her floatplane to reconnoiter Zanzibar and Dar-es Salaam. The pilot sights one merchant in the harbor and one 4,000-ton vessel departing. During landing, one of the Glens floats is damaged, but it is hoisted aboard.

20 May 1942:
I-30 carries out periscope observation of the port at Kilindini (Mombasa).

24 May 1942:
At night, I-30 carries out periscope observation of Diego Suarez at the northern tip of Madagascar at Antsiranana, on the Indian Ocean.

29 May 1942:
At night, I-10's floatplane reconnoiters the harbor at Diego Suarez. The plane sights HMS RAMILLES, an old 29,150-ton ROYAL SOVEREIGN-class battleship, at anchor in the bay. Also in the harbor are destroyers HMS DUNCAN and ACTIVE, corvettes HMS GENISTA and THYME, troopship HMS KARANJA, hospital ship ATLANTIS, tanker BRITISH LOYALTY, 10,799-ton merchant LLANDAFF CASTLE and an ammunition ship.

Captain Ishizaki orders a midget submarine attack for the next night.

30 May 1942:
I-16 and I-20 launch their midget submarines about 10 miles from Diego Suarez to penetrate the harbor. At 2025, a midget torpedoes and heavily damages RAMILLES. British corvettes drop depth charges, but at 2120 a midget from I-20 torpedoes and sinks 6,993-ton BRITISH LOYALTY in shallow water. (She is later refloated and sunk off Addu Atoll).

June 1942:
Indian Ocean. E of Madagascar. After the midget attack, I-30 patrols for a short while, then detaches from SubRon 8 and heads west on a Yanagi* mission. She is attached directly to Headquarters, Sixth Fleet for the duration of the voyage. The 10th Naval Signal Unit at Singapore relays radio traffic from the Sixth Fleet to I-30. Cdr Endo's boat remains silent for the whole voyage.

18 June 1942:
Off Madagascar. I-30 is refueled and refurbished by AIKOKU MARU for the last time.

30 June 1942:
300 miles S of Durban. I-30 is spotted by a South African Air Force patrol plane, but escapes without damage. Later, she rounds the Cape of Good Hope and enters the Atlantic enroute to France.

2 August 1942:
I-30 is code-named Sakura ("Cherry Blossom") by the Japanese and "U-Kirschblüte" by the Germans. She arrives in the Bay of Biscay. Off Cape Ortegal, she is met by eight Luftwaffe Junkers Ju-88 attack bombers that provide cover.

5 August 1942:
I-30 is met by eight German M-class minesweepers and one Sperrbrecher (mine barrage breaker) who escort her to Lorient - the largest of the five German U-boat bases on the French coast. I-30 is the first Japanese submarine to arrive in Europe during World War II.

I-30 ties up to a buoy and her crew is transferred by a French tender to the deck of U-67. Cdr Edo and his crew are greeted by Grossadmiral Erich Raeder, Oberbefehlshaber (CINC) der Kriegsmarine (OKM), Admiral (later Grossadmiral/Fuhrer) Karl Dönitz, Befehlshaber der Unterseeboote (BdU) and the Japanese Naval Attaché to Germany Captain (later Rear Admiral) Yokoi Tadao who have traveled from their headquarters for the occasion.

The Lorient station band plays martial music and Cdr Edo is decorated with a German medal. A woman presents him with a bouquet of flowers traditionally given to successful arriving U-boat commanders. Ashore, U-boat men, soldiers, nurses, signals women and civilians line up to greet I-30.

Later, I-30's cargo is unloaded. She carries 3,300-lbs. of mica and 1,452- lbs. of shellac for the Germans. I-30 also carries the blueprints of the Type 91 aerial torpedo, but her own Type 95 oxygen-propelled torpedoes were removed for the voyage and substituted with 14 Type 89 steam torpedoes so as not to reveal the Type 95's secrets. (The following year, I-8 is the first IJN submarine to deliver Type 95s to the Germans.) [2]

6 August 1942:
An official greeting is held for I-30's crew that includes a banquet dinner in the Grand Hall of the former French naval arsenal. The dinner is attended by the I-30's officers, Japanese naval attaches, German Army and Navy officers and a few civilians.

Lorient is the home of the 2nd U-Flotille "Saltzwedel" commanded by Knight's Cross with Oak Leaves winner Korvettenkapitän (later Kapitän zur See) Viktor Schütze (former CO of U-103) and the 10th U-Flotille commanded by Knight's Cross winner Korvettenkapitän (later Konteradmiral, Bundesmarine) Günter Kuhnke (former CO of U-28). The German submariners welcome Cdr Endo and entertain I-30's officers and men. [3]

Some Japanese and German enlisted men exchange their cap bands, an old naval custom. Although Japanese crewmen are allowed inside a U-boat where they take many pictures, no German enlisted men are permitted to board I-30.

Later, I-30 is moved into one of Lorient's 16 bombproof U-Boat pens in the Keroman bunker. I-30 is refitted and painted the same grey as the U-boats. Kriegsmarine experts examine her and find that her engine and hull noise levels are unreasonably high. She is fitted with a a Metox radar detector and a Mauser "Flakvierling 38" quad 20-mm AA gun replacing her Type 96 25-mm AA guns. [4]

I-30's floatplane is repaired and painted with false Japanese markings. During the floatplane's test flights, film footage is shot and later used to prove the existence of an IJNAF Naval Air Corps operating from French bases.

Endo and his crew travel to Berlin where he is awarded a medal by Adolf Hitler. Later, he and his crew travel to Paris where they visit the Eiffel Tower and the Champs-Elysées before returning to Lorient.

22 August 1942:
I-30 departs Lorient. Cdr Endo leaves behind I-30's E14Y1 floatplane as a "souvenir" of his visit for the Germans.

I-30 carries one Japanese engineer as a passenger. Her cargo includes blueprints of the Würzburg air defense ground radar and one complete set, five German G7a aerial torpedoes and three G7e electric torpedoes, five Torpedovorhalterechner (torpedo data computers), 240 Bolde sonar countermeasure rounds, rocket and glider bombs, antitank guns, Zeiss anti-aircraft artillery (AAA) director (fire control system), 200 20-mm AA guns, industrial diamonds valued at one million yen and fifty top secret "T-Enigma" coding machines.

22 September 1942:
I-30 rounds the Cape of Good Hope. Three days later, German news agencies announce that a Japanese submarine has joined their U-boats operating in Atlantic Ocean.

8 October 1942:
Early in the morning, I-30 arrives at Penang. Rear Admiral Hoshina Zenshiro (former CO of MUTSU), Chief of Ministry of the Navy's Logistics Section, without consulting the NGS, requests ten T-Enigmas from I-30's cargo for use by his headquarters at Singapore.

9 October 1942:
The I-30 arrives at Penang where she refuels and replenishes.

11 October 1942:
In the evening, I-30 departs Penang for Singapore.

13 October 1942:
I-30 arrives off Singapore during the night. Cdr Endo requests a pilot from the No. 10 Special Base Unit, but fails to contact the base because his codes are outdated. Endo then decides to independently navigate the harbor entrance.

At 0930, I-30 arrives at Keppel harbor, Singapore. The 10 T-Enigmas are disembarked. Cdr Endo dines with the C-in-C, First Southern Expeditionary Fleet, Vice Admiral Okawachi Denshichi (former CO of HIEI) and the staff of the No. 10 Special Base Unit.

The I-30's navigator receives maps of the mine swept area around Singapore. At 1609, she departs for Kure. Three miles E of Keppel harbor she hits a British mine and quickly sinks. Cdr Endo and 96 crewmen are rescued, but 13 men are lost. (In February 1944, off Truk, Cdr Endo is KIA as CO of I-43).

Divers from the No. 101 Navy Repair Unit recover some of the I-30's cargo including most of the 20-mm guns, TDCs and radar blueprints, but the model of the Würzburg radar is destroyed and the drawings for it are rendered unusable by the salt water.

15 February 1943:
Four months later, Tokyo finally informs Berlin of the loss the 40 Enigma machines aboard the I-30. They also inform the Germans of the 1 February 1943 sinking of I-1 in shallow water at Guadalcanal that possibly compromised the Japanese-German joint-use "Sumatra" code.

15 April 1944:
Removed from the Navy List.

August 1959-February 1960:
Salvaged/scrapped by Hokusei Sempaku Kogyo K.K.

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Author's Notes:
[1[ When Japan enters the war, the Axis Tripartite agreement is amended to provide for an exchange of strategic materials and manufactured goods between Europe and the Far East. Surface ships make the initial "Yanagi" exchanges, but when that is no longer possible, submarines are used.

[2] Mica has applications in electrical capacitor devices and shellac is used in military pyrotechnics.

[3] Schütze was the fifth leading U-boat "Ace" with 35 ships sunk for 180,073-tons and two ships damaged in seven patrols.

[4] The roof of the bunker was made of 22-feet of reinforced concrete - impervious to all Allied bombs except Barnes Wallis' 12,000-lb."Tallboy" penetrator developed later in the war.

Special thanks go to Dr. Higuchi Tatsuhiro of Japan and Andrew Obluski of Poland.

– Bob Hackett and Sander Kingsepp

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