''Ro-66'' was an

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...

Type L

submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...

of the L4 subclass. First commissioned in 1927, she served in the waters of

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

prior to

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. During World War II, she operated in the Central Pacific and supported Japanese forces in the

Battle of Wake Island The Battle of Wake Island was a battle of the Pacific campaign of World War II, fought on Wake Island. The assault began simultaneously with the attack on Pearl Harbor naval and air bases in Hawaii on the morning of 8 December 1941 (7 December ...

until she sank after a collision in December 1941.

Design and description

The submarines of the Type L4 sub-class were copies of the Group 3 subclass of the British L-class submarine built under license in Japan.Chesneau, Roger, ed., ''Conway′s All the World′s Fighting Ships 1922–1946'', New York: Mayflower Books, 1980, , p. 203. They were slightly larger and had two more

torpedo tube A torpedo tube is a cylindrical device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers) installed aboa ...

s than the preceding submarines of the L3 subclass. They displaced surfaced and submerged. The submarines were long and had a

beam Beam may refer to: Streams of particles or energy *Light beam, or beam of light, a directional projection of light energy **Laser beam *Particle beam, a stream of charged or neutral particles **Charged particle beam, a spatially localized grou ...

of and a

draft Draft, The Draft, or Draught may refer to: Watercraft dimensions * Draft (hull), the distance from waterline to keel of a vessel * Draft (sail), degree of curvature in a sail * Air draft, distance from waterline to the highest point on a vessel ...

of . They had a diving depth of . For surface running, the submarines were powered by two

Vickers Vickers was a British engineering company that existed from 1828 until 1999. It was formed in Sheffield as a steel foundry by Edward Vickers and his father-in-law, and soon became famous for casting church bells. The company went public in 18 ...

diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...

s, each driving one

propeller shaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power and torque and rotation, usually used to connect ...

. When submerged, each propeller was driven by an

electric motor An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...

. They could reach on the surface and underwater. On the surface, they had a range of at ; submerged, they had a range of at . The submarines were armed with six internal

s, all in the bow, and carried a total of twelve 6th Year Type torpedoes. They were also armed with a single deck gun and a 6.5 mm

machine gun A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) a ...

Construction and commissioning

''Ro-66'' was

laid down Laying the keel or laying down is the formal recognition of the start of a ship's construction. It is often marked with a ceremony attended by dignitaries from the shipbuilding company and the ultimate owners of the ship. Keel laying is one o ...

on 1 December 1925 by

Mitsubishi The is a group of autonomous Japanese multinational companies in a variety of industries. Founded by Yatarō Iwasaki in 1870, the Mitsubishi Group historically descended from the Mitsubishi zaibatsu, a unified company which existed from 1870 ...

Kobe Kobe ( , ; officially , ) is the capital city of Hyōgo Prefecture Japan. With a population around 1.5 million, Kobe is Japan's seventh-largest city and the third-largest port city after Tokyo and Yokohama. It is located in Kansai region, whic ...

. Launched on 25 October 1926, she was completed and commissioned on 28 July 1927.

Service history

Pre-World War II

Upon commissioning, ''Ro-66'' was attached to the

Sasebo Naval District was the third of five main administrative districts of the pre-war Imperial Japanese Navy. Its territory included the western and southern coastline of Kyūshū, the Ryukyu Islands, Taiwan and Korea, as well as patrols in the East China Sea and t ...

and assigned to Submarine Division 27 — in which she spent her entire career — in Submarine

Squadron Squadron may refer to: * Squadron (army), a military unit of cavalry, tanks, or equivalent subdivided into troops or tank companies * Squadron (aviation), a military unit that consists of three or four flights with a total of 12 to 24 aircraft, de ...

1 in the 1st Fleet in the

Combined Fleet The was the main sea-going component of the Imperial Japanese Navy. Until 1933, the Combined Fleet was not a permanent organization, but a temporary force formed for the duration of a conflict or major naval maneuvers from various units norm ...

. Submarine Division 27 was reassigned to the Sasebo Defense Division in the Sasebo Naval District on 30 November 1929. On 24 December 1929, the division was reassigned to Submarine Squadron 2 in the 2nd Fleet in the Combined Fleet. ''Ro-66'' was decommissioned and placed in reserve at

Sasebo is a core city located in Nagasaki Prefecture, Japan. It is also the second largest city in Nagasaki Prefecture, after its capital, Nagasaki. On 1 June 2019, the city had an estimated population of 247,739 and a population density of 581 persons p ...

, Japan, on 15 November 1930. ''Ro-66'' was recommissioned on 1 May 1931, resuming active service in Submarine Division 27, which by then had been reassigned to the Sasebo Defense Division in the Sasebo Naval District. On 1 October 1932, the division was reassigned to the Sasebo Guard Squadron. On 15 November 1933, the division returned to service in the Sasebo Defense Division, and that day ''Ro-66'' again was decommissioned and placed in reserve at Sasebo. ''Ro-66'' was recommissioned on 15 November 1934, and returned to service in Submarine Division 27 which by then again was serving in the Sasebo Guard Squadron in the Sasebo Naval District. The division was transferred to the Sasebo Defense Squadron on 15 November 1935. Sources offer different accounts of ''Ro-66''′s status during 1938–1940, implying both that she was in full commission throughout those years and stating that she was out of commission and in reserve — in Second Reserve from 15 December 1938 to 15 November 1939 and then in First Reserve until 15 November 1940 — in the Sasebo Naval District between December 1938 and November 1940. Whatever the case, she was back in active service in time for Submarine Division 27′s reassignment to Submarine Squadron 7 in the 4th Fleet in the Combined Fleet on 15 November 1940. When the Imperial Japanese Navy deployed for the upcoming conflict in the Pacific, ''Ro-66'' was at

Kwajalein Kwajalein Atoll (; Marshallese: ) is part of the Republic of the Marshall Islands (RMI). The southernmost and largest island in the atoll is named Kwajalein Island, which its majority English-speaking residents (about 1,000 mostly U.S. civilia ...

in the

Marshall Islands The Marshall Islands ( mh, Ṃajeḷ), officially the Republic of the Marshall Islands ( mh, Aolepān Aorōkin Ṃajeḷ),'' () is an independent island country and microstate near the Equator in the Pacific Ocean, slightly west of the Internati ...

with the other submarines of Submarine Division 27, and . She received the message "Climb

Mount Niitaka Yu Shan or Yushan, also known as Mount Jade, Jade Mountain, or , and known as Mount Niitaka during Taiwan under Japanese rule, Japanese rule, is the highest mountain in Taiwan at above sea level, giving Taiwan the List of islands by highes ...

1208" ( ja, Niitakayama nobore 1208) from the Combined Fleet on 2 December 1941, indicating that war with the

Allies An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...

would commence on 8 December 1941

Japan time , or , is the standard time zone in Japan, 9 hours ahead of UTC (UTC+09:00). Japan does not observe daylight saving time, though its introduction has been debated on several occasions. During World War II, the time zone was often referred to as ...

, which was on 7 December 1941 on the other side of the

International Date Line The International Date Line (IDL) is an internationally accepted demarcation on the surface of Earth, running between the South and North Poles and serving as the boundary between one calendar day and the next. It passes through the Pacific O ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

, where Japanese plans called for the war to open with their

attack on Pearl Harbor The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service upon the United States against the naval base at Pearl Harbor in Honolulu, Territory of Hawaii, j ...

World War II

Battle of Wake Island

On 6 December 1941, ''Ro-66'' got underway from Kwajalein with the commander of Submarine Squadron 27 embarked to conduct a reconnaissance of

Wake Island Wake Island ( mh, Ānen Kio, translation=island of the kio flower; also known as Wake Atoll) is a coral atoll in the western Pacific Ocean in the northeastern area of the Micronesia subregion, east of Guam, west of Honolulu, southeast of To ...

, which the Japanese planned to invade on 8 December 1941, the first day of the war on Wake Island′s side of the International Date Line. The

began on 8 December 1941, with ''Ro-65'', ''Ro-66'', and ''Ro-67'' patrolling in the area supporting Japanese forces attempting to seize the

atoll An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can gr ...

United States Marine Corps The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through combi ...

forces defending Wake drove back the initial Japanese assault that day. While the Japanese gathered reinforcements for a second and larger invasion of the island, Submarine Squadron 7 sent orders to all three submarines of Submarine Division 27 on 12 December 1941 directing them to return to Kwajalein. Accordingly, ''Ro-65'' and ''Ro-67'' headed back to Kwajalein, but a radio failure prevented ''Ro-66'' from receiving the orders despite three attempts by Submarine Squadron 7 to contact her. Consequently, she continued to patrol off Wake Island as the submarines of Submarine Division 26 — , ,and — arrived in the area to relieve the departing submarines.

Loss

''Ro-66'' was on the surface southwest of Wake Island — bearing 252 degrees from the atoll — to recharge her

batteries Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...

in a heavy

squall A squall is a sudden, sharp increase in wind speed lasting minutes, as opposed to a wind gust, which lasts for only seconds. They are usually associated with active weather, such as rain showers, thunderstorms, or heavy snow. Squalls refer to the ...

in the predawn darkness of 17 December 1941 when her lookouts suddenly sighted ''Ro-62'', also on the surface and recharging batteries. Both submarines attempted to back off, but it was too late to avoid a collision, and ''Ro-62'' rammed ''Ro-66'' at 20:20

Japan Standard Time , or , is the standard time zone in Japan, 9 hours ahead of UTC ( UTC+09:00). Japan does not observe daylight saving time, though its introduction has been debated on several occasions. During World War II, the time zone was often referred to a ...

. ''Ro-66'' sank at with the loss of 63 lives, including that of the commander of Submarine Division 27. ''Ro-62'' rescued her three survivors, who had been thrown overboard from her

bridge A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...

by the collision. The Battle of Wake Island concluded on 23 December 1941 with the Japanese conquest of the atoll. The Japanese struck ''Ro-66'' from the Navy list on 15 January 1942.

References

Bibliography

*'', History of Pacific War Extra, "Perfect guide, The submarines of the Imperial Japanese Forces"'', Gakken (Japan), March 2005, *''The Maru Special, Japanese Naval Vessels No.43 Japanese Submarines III'', Ushio Shobō (Japan), September 1980, Book code 68343-44 *''The Maru Special, Japanese Naval Vessels No.132 Japanese Submarines I "Revised edition"'', Ushio Shobō (Japan), February 1988, Book code 68344-36 *''The Maru Special, Japanese Naval Vessels No.133 Japanese Submarines II "Revised edition"'', Ushio Shobō (Japan), March 1988, Book code 68344-37

External links

Photo of ''Ro-66'' at combinedfleet.com
{{DEFAULTSORT:Ro-066 Ro-60-class submarines Japanese L type submarines Ships built by Mitsubishi Heavy Industries 1926 ships World War II submarines of Japan Maritime incidents in November 1942 Japanese submarine accidents Submarines sunk in collisions Japanese submarines lost during World War II World War II shipwrecks in the Pacific Ocean