IJN Submarine RO-500 (Ex-U-511):
Tabular Record of
© 2001-2018 Bob Hackett & Sander Kingsepp
21 February 1941:
Hamburg, Germany. A 1,120-ton (surfaced)
type IXC U-boat, is laid down at Deutsche Werft AG.
22 September 1941:
Launched and numbered U-511.
8 December 1941:
Completed and commissioned in the Kriegsmarine.
Kapitänleutnant Friedrich Steinhoff is the Commanding Officer.
31 May-5 June 1942:
Peenemünde, Germany. Steinhoff and his brother Dr.
Ernst Steinhoff, an engineer at the Peenemünde rocket development facility,
discuss the feasibility of firing an artillery rocket from the deck of a
submerged submarine. During the summer, U-511 is used for rocket tests on the
Baltic coast of Germany. A rack for six 30-cm Wurfkörper 42 Sprengraketen
rockets is installed. Tests are carried out, including a successful launch of
the rockets from a depth of 12 meters.
Vizeadmiral Karl Dönitz, Befehlshaber der Unterseeboote (BdU)
(CINC, U-boats), approves the concept of launching the rockets against New York
City, but the plan is delayed for technical reasons and is eventually cancelled.
August 1942-July 1943:
U-511 sinks five ships for a total of 41, 373
tons and damages an 8,773-ton tanker. 
18 December 1942:
Kapitänleutnant Fritz Schneewind assumes command.
Steinhoff later becomes the CO of U-873.
26 February 1943:
Vinnitsa, Ukraine. During a conference with Dönitz
in Führer’s HQ, Hitler makes the final decision about the transfer of two
Kriegsmarine U-boats to Japan in order to launch a full-scale campaign against
Allied communications in the Indian Ocean. Dönitz opposes the idea, but is
3 March 1943:
Vice Admiral Nomura Naokuni (35)(former CO of KAGA),
Japan's representative to the Axis Tripartite Commission in Berlin since 1941,
is ordered to return to Japan on the next outgoing submarine. Japanese naval
attaché Rear Admiral Yokoi Tadao (former CO of CHIYODA) also authorizes the
departure of Maj Sugita Tamotsu of the IJA Medical Service, who had been
studying in Germany.
Late April 1943:
Vice Admiral Nomura and Maj Sugita are invited to a
farewell party in Hitler’s Berlin residence. During that party Field Marshal
Wilhelm Keitel, Chief of the German Wehrmacht, personally authorizes
export of Daimler-Benz MB-518 diesel engines for use on Japanese torpedo boats.
The first example is sent to Lorient, France, for embarkation on U-511.
10 May 1943:
Lorient, France. Early in the morning, Vice Admiral
Nomura and Maj Sugita arrive by train from Berlin. After 1300, U-511 ("Marco
Polo 1") departs for Penang, Malaya. U-511 also carries a full set of
Messerschmitt Me-163 "Komet” rocket interceptor blueprints, samples of yellow
fever vaccine, spare torpedoes and supplies for the German U-boat "Gruppe
Monsun" (Monsoon) being organized at Penang. 
U-511 carries a crew of 49 and nine passengers - five Germans and four
Japanese. Among the Japanese are Vice Admiral Nomura and Major Sugita. The
Germans include Dr. Ernst Wörmann, ambassador to Wang Jing-we's pro-Japanese
collaborationist government at Nanking, China and Franz-Joseph Spahn, en route
to Japan as an "overseer" for the Jewish refugee policy in Manila and three
engineers from U-boat builder Deschimag AG Weser at Bremen: Mssrs. Herberlein,
an auxiliary engine specialist Hans Schmidt, a welding technician, and Müller of
the Type IXC construction office.
During transit, U-511 is designated by the Japanese as "Satsuki (Month of
First Buds) No. 1."
22 May 1943:
W of Freetown, Liberia, Africa. U-511 makes a planned
rendezvous with Kapitänleutnant Ebe Schnoor's U-460, a Type XIV "Milchkuh" (Milk
Cow) tanker. U-511 takes on fuel and provisions. After refueling U-511, U-460
departs for France arriving on 25 June. U-511 heads for the Indian Ocean.
27 May 1943:
U-511, travelling at an average submerged speed of 3
knots, crosses the equator.
10 June 1943:
U-511 enters the Indian Ocean.
27 June 1943:
Indian Ocean. U-511 torpedoes 7,194-ton American
"Liberty" ship SEBASTIAN CERMENO en route from Mombasa, Kenya to Bahia, Brazil.
She sinks at 28-50S, 50-20E. Schneewind surfaces to question survivors, then
submerges and retires from the area.
9 July 1943:
Indian Ocean. U-511 torpedoes 7,176-ton American Liberty
ship SAMUEL HEINTZELMAN en route from Fremantle, Australia via Colombo, Ceylon
to Calcutta, India, loaded with 5,644-tons of ammunition. When the torpedoes hit
the ship, she disintegrates in a massive explosion! The entire crew of 75
perishes. She sinks at 09-00S, 81-00E.
15 July 1943:
Andaman Sea. At the appointed time, U-511 makes a
rendezvous with minelayer HATSUTAKA attached to the First Southern Expeditionary
Fleet. Vice Admiral Nomura and Major Sugita briefly visit HATSUTAKA for a bath
and then return to the U-boat.
16 July 1943:
Penang, Malaya. U-511 is the first German U-boat to
arrive at the base. It subsequently becomes home for the "Monsun" Group. Admiral
Nomura disembarks and he and the other Japanese continue on to Japan by air.
Schneewind embarks a group of IJN officers including Lt Honda Yoshikuni (former
navigating officer of I-17 and future CO of RO-41). 
24 July 1943:
At 1600, U-511 departs Penang for Kure. 
29 July 1943:
At 1650, the surfaced U-511 encounters Singapore-bound
convoy HI-03 consisting of ARIMASAN, ASAMA, AWA and NANKAI MARUs and tanker
OMUROSAN MARU. The convoy is escorted by kaibokan ETOROFU. The sighting of a
strange-looking submarine causes confusion aboard OMUROSAN MARU and her gunners
fire three shells at U-511, before the mistake is cleared up. The skipper of
ETOROFU inspects U-511 and personally apologizes for the attack. 
5 August 1943:
Off the Bungo Suido (Strait). At 0800 U-55
rendezvouses with minelayer NUWAJIMA appointed to escort her for the remainder
of voyage. Soon thereafter, a Japanese patrol aircraft reports the sighting of a
submarine en route of U-511. NUWAJIMA conducts a depth-charge attack, while
Schneewind continues the voyage independently. U-511 and NUWAJIMA stop at
Agenosho Bay off Yashiro Jima for the night.
7 August 1943:
Kure. U-511 arrives. Kapitänleutnant Schneewind and
his crew are hosted by the CO of the Kure Naval Base, Vice Admiral (Admiral,
posthumously) Nagumo Chuichi (36)(former CO of YAMASHIRO). Schneewind and
several officers later travel to Tokyo, where they receive decorations from Navy
Minister Admiral Shimada Shigetaro (32)(former CO of HIEI) and Chief of the NGS,
Fleet Admiral Nagano Osami (28)(former CO of HIRADO).
16 September 1943:
Kure. U-511 is formally handed over, commissioned
in the IJN as RO-500 and attached to Kure Naval District. LtCdr Taoka Kiyoshi
(55)(former CO of I-54) is the Commanding Officer. 
Kure. RO-500 is put through trials and evaluated by a team of IJN
engineers led by Constructor Vice Admiral Fukuda Keiji, one of the designers of
the YAMATO class battleships. The IJN team is assisted by three German engineers
attached to the Naval Technical Institute in Tokyo. After careful study, the
engineers point out several shortcomings of the IXC design, such as low
underwater speed, unreliable diesel engines, inadequate ventilation and cooling
equipment and limited range.
Earlier, a proposition was put forward to launch serial production of
Type IXC submarines equipped with Japanese powerplants and weapons (tentatively
designated as IXK by the Germans). Vice Admiral Fukuda rejects the proposition
and instead recommends that all available resources be devoted to construction
of the new I-201-class ("Sen Taka") high underwater speed submarines. Several
features of U-511 are used in this design, including the electric welded
pressure hull, prefabricated hull section, and re-designed engine mountings to
reduce vibration and engine noise.
Late September 1943:
Kure. After teaching handling of the U-boat to
the Japanese, U-511's German crew departs aboard the Italian freighter OSORNO
bound for Singapore. Later, the crewmen make their way to Penang. 
1 November 1943:
RO-500 is attached to the Otake Submarine School for
testing and training purposes.
3 December 1943:
LtCdr Taoka is attached to Headquarters, Sixth Fleet.
RO-500's torpedo officer Lt Uesugi Sadao (65)(former torpedo officer of I-20) is
appointed the acting CO of RO-500.
31 January 1944:
RO-500's torpedo officer Lt Yamazaki Toshio (67) is
appointed the acting CO of RO-500.
30 April 1944:
Lt (later LtCdr) Shiizuka Mitsuo (66)(former torpedo
officer of I-185) is appointed the CO.
2 May 1944:
Assigned to SubDiv 33 at Kure with RO-62, RO-63 and RO-64.
Later that month, RO-500 commences joint exercises with Yokosuka D4Y2 Suisei
("Judy") dive-bombers of the 634th NAG, soon to be embarked on the hybrid
carriers of the ISE class. RO-500 acts as the ASW target for the dive-bomber
1 July 1944:
Reassigned to Kure Guard Unit.
5 July 1944:
Lt (later LtCdr) Yamamoto Yoshio (66)(former torpedo
officer of I-361) is appointed the CO.
15 August 1944:
RO-500 is in the Kure Naval District with RO-62 and
RO-68. Training duties.
15 September 1944:
Lt Yamamoto Yasuhisa (67)(former navigating officer
of RO-114) is appointed the CO.
Late September 1944:
The staff of Saeki NAG requests two submarines
from the Kure Naval Base HQ to simulate "intruders" for ASW aircraft crews.
RO-500 is one of the candidates with RO-68, but cannot participate because of
5 May 1945:
Reassigned to 51st Escort Squadron at Maizuru to simulate
US submarines for subchaser/kaibokan crews.
Kure Navy Yard. I-155 through I-158 are repainted to test the efficiency
of the German light grey camouflage scheme. Subsequent trials reveal no
advantages over the scheme used on Japanese submarines.
12 August 1945:
Arrives at Maizuru following the Soviet invasion of
Manchuria. Embarks fuel and ammunition.
15 August 1945: End of Hostilities with the Allies:
joins the rebels and decides to continue fighting against the Soviets.
18 August 1945:
Early in the morning departs Maizuru for Sakhalin
waters. Sixth Fleet HQ learns about the sortie and addresses the crew of RO-500
by radio. A floatplane manages to locate the submarine and on the evening of
18th she returns to Maizuru.
Maizuru Navy Base. RO-500 is surrendered to Allied
10 October 1945:
Removed from the Navy List.
13 October 1945:
At Maizuru with I-121, I-201, I-202, RO-18 and RO-68.
30 April 1946:
Off Kanmuri Jima, Wakasa Bay. RO-500 is scuttled by
the U.S. Navy.
(I-121, RO-68 and RO-500's final day at Maizuru)
18-21 June 2018:
The Society La Plongée for Deep Sea Technology research
team led by Research Professor Ura Tamaki from Kyushu Institute of Technology
locates and photographes the wrecks of RO-500, I-121 and RO-68, using a
multibeam echosounder and an ROV. The wreck of RO-500 is located at the depth
of 290 ft and identified by its distinctive bow shape.
 This total of ships sunk includes both ships sunk by
U-511 while she was enroute to Japan.
 One of three sets of Me-163 blueprints carried to Japan by submarine;
the others are later carried aboard I-29 and RO-501. Only the Me-163 blueprints
carried on U-511 and I-29 made it to Japan. They were used to develop the
Mitsubishi J8MI Shusui ("Sword Stroke").
 Nomura later becomes the CINC, Kure Naval Station and, as a full
Admiral in 1944, Vice Minister of the Navy. Many authors confuse Admiral Nomura
Naokuni (35) with Admiral Nomura Kichisaburo (26).
 Axis propaganda asserted U-511 was a "gift" from Hitler to Emperor
Hirohito. Actually, the Germans treated U-511 as a partial payment for Japanese
supplies (raw rubber and torpedoes in particular) already delivered by surface
blockade runners. The Japanese and Germans always dealt on a strictly hard
currency (or gold) basis.
 According to some German sources, Captain Okuda Masuzo had been
appointed CO of U-511 by then. This is incorrect, since Okuda was the
highest-ranking passenger aboard the submarine during her voyage to Kure. The
first Japanese skipper of U-511/RO-500 was appointed on 16 September 1943.
 In some postwar German sources the "friendly fire" accident of 29
July has grown into a major naval battle between the U-511 and the surface units
of the IJN. Moreover, they state that the "battle" could only be stopped after
Vice Admiral Nomura challenged the attackers by radio. In reality, Nomura had
already left the sub at Penang, after he developed heart trouble.
 U-511's crew later becomes a spare crew for the U-boats that operate
from Penang. They also form the backbone of repair and maintenance capability of
that small (five U-boat) base.
On 20 Nov '43, Schneewind is given command of U-183 at Penang. He was KIA
23 April 1945 in the Java Sea when U-183 was torpedoed and sunk by USS BESUGO
Thanks go to Dr. Higuchi Tatsuhiro of Japan. Special thanks for
assistance in researching the IJN officers mentioned in this TROM go to Mr.
Jean-François Masson of Canada.
-Bob Hackett and Sander Kingsepp.
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